U.S. patent application number 17/287168 was filed with the patent office on 2021-11-25 for sensor network for measuring physiological parameters of mammal subject and applications of same.
The applicant listed for this patent is NORTHWESTERN UNIVERSITY. Invention is credited to Ha Uk CHUNG, Aurelie HOURLIER-FARGETTE, Jong Yoon LEE, Kun Hyuck LEE, John A. ROGERS, Alina RWEI, Shuai XU.
Application Number | 20210361165 17/287168 |
Document ID | / |
Family ID | 1000005783675 |
Filed Date | 2021-11-25 |
United States Patent
Application |
20210361165 |
Kind Code |
A1 |
ROGERS; John A. ; et
al. |
November 25, 2021 |
SENSOR NETWORK FOR MEASURING PHYSIOLOGICAL PARAMETERS OF MAMMAL
SUBJECT AND APPLICATIONS OF SAME
Abstract
A sensor network for measuring physiological parameters of a
mammal subject includes a plurality of spatially separated sensor
systems that is time-synchronized to each other. Each of the
plurality of spatially separated sensor systems is attached to a
respective position of the mammal subject and includes a sensor
member for measuring at least one physiological parameter, a system
on a chip (SoC) having a microprocessor coupled to the sensor
member for receiving data from the sensor member and processing the
received data, and a transceiver coupled to the SoC for wireless
data transmission and wireless power harvesting. The sensor network
also includes a microcontroller unit (MCU) adapted in wireless
communication with the plurality of spatially separated sensor
systems for wirelessly transmitting data to and from the plurality
of spatially separated sensor systems.
Inventors: |
ROGERS; John A.; (Wilmette,
IL) ; XU; Shuai; (Bala Cynwyd, PA) ; CHUNG; Ha
Uk; (Evanston, IL) ; LEE; Kun Hyuck;
(Evanston, IL) ; HOURLIER-FARGETTE; Aurelie;
(Evanston, IL) ; RWEI; Alina; (Evanston, IL)
; LEE; Jong Yoon; (Evanston, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NORTHWESTERN UNIVERSITY |
Evanston |
IL |
US |
|
|
Family ID: |
1000005783675 |
Appl. No.: |
17/287168 |
Filed: |
October 31, 2019 |
PCT Filed: |
October 31, 2019 |
PCT NO: |
PCT/US2019/059156 |
371 Date: |
April 21, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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62753303 |
Oct 31, 2018 |
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62753453 |
Oct 31, 2018 |
|
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62753625 |
Oct 31, 2018 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 2562/0219 20130101;
A61B 5/747 20130101; A61B 5/0816 20130101; A61B 5/4205 20130101;
A61B 5/0051 20130101; A61B 5/02405 20130101; A61B 5/0024 20130101;
A61B 5/7285 20130101; A61B 5/746 20130101; A61B 2560/0214 20130101;
A61B 5/7207 20130101; A61B 5/0022 20130101; A61B 2562/0204
20130101; A61B 2562/0271 20130101; A61B 5/11 20130101; A61B 5/0261
20130101; A61B 5/02028 20130101; A61B 2503/045 20130101; A61B
2562/162 20130101; A61B 2562/227 20130101; A61B 5/0004 20130101;
A61B 5/28 20210101; A61B 5/02427 20130101; A61B 2503/40 20130101;
A61B 5/01 20130101; A61B 5/6801 20130101; A61B 5/14552
20130101 |
International
Class: |
A61B 5/00 20060101
A61B005/00; A61B 5/1455 20060101 A61B005/1455; A61B 5/28 20060101
A61B005/28; A61B 5/024 20060101 A61B005/024; A61B 5/02 20060101
A61B005/02; A61B 5/01 20060101 A61B005/01; A61B 5/08 20060101
A61B005/08; A61B 5/11 20060101 A61B005/11; A61B 5/026 20060101
A61B005/026 |
Claims
1. A sensor network for measuring physiological parameters of a
mammal subject, comprising: a plurality of spatially separated
sensor systems that is time-synchronized to each other, wherein
each of the plurality of spatially separated sensor systems is
attached to a respective position of the mammal subject and
comprises a sensor member for measuring at least one physiological
parameter, a system on a chip (SoC) having a microprocessor coupled
to the sensor member for receiving data from the sensor member and
processing the received data, and a transceiver coupled to the SoC
for wireless data transmission and wireless power harvesting; and a
microcontroller unit (MCU) adapted in wireless communication with
the plurality of spatially separated sensor systems for wirelessly
transmitting data to and from the plurality of spatially separated
sensor systems.
2. The sensor network of claim 1, wherein each two adjacent sensor
systems are spatially separated by a respective distance that is
adjustable between a minimal distance and a maximal distance.
3. The sensor network of claim 1, wherein the plurality of
spatially separated sensor systems comprises a first sensor system
configured to attach to a central region of the mammal subject and
a second sensor system configured to attach to an extremity region
of the mammal subject.
4. The sensor network of claim 3, wherein the central region
comprises one or more of a chest region, a neck region including a
suprasternal notch area, and a head region including a forehead
region or an anterior fontanelle region of the mammal subject, and
wherein the extremity region comprises one or more of a limb
region, a foot region, a hand region, a toenail region, and a
fingernail region of the mammal subject.
5. The sensor network of claim 4, wherein the sensor member of the
first sensor system comprises at least two electrodes spatially
apart from each other for electrocardiogram (ECG) generation.
6. The sensor network of claim 4, wherein the sensor member of the
second sensor system comprises a photoplethysmogram (PPG) sensor
comprising an optical source and an optical detector located within
a sensor footprint.
7. The sensor network of claim 5, wherein the sensor member further
comprises one or more of: an accelerometer for measuring at least
one of a position and a movement; an inertial measurement unit
(IMU) for measuring at least one of a movement, a force, an angular
rate, and an orientation; a temperature sensor for measuring
temperature.
8. The sensor network of claim 7, wherein the accelerometer or the
IMU is used to measure at least one of seismocardiography (SCG) and
a respiratory rate.
9. The sensor network of claim 7, wherein the accelerometer or the
IMU is used with a motion artifact module to identify a vital sign
as subject to motion artifact and to correct of motion
artifact.
10. The sensor network of claim 1, wherein the sensor member
comprises one or more of an ECG sensor, an EKG sensor, a pulse
oximeter sensor, a temperature sensor, a blood pressure sensor, an
accelerometer, or an acoustic sensor.
11. The sensor network of claim 1, wherein the physiological
parameters comprise one or more of heart activities including a
stroke volume and ejection fraction, oxygenation level,
temperature, skin temperature differentials, body movement, body
position, breathing parameters, blood pressure, crying time, crying
frequency, swallow count, swallow frequency, chest wall
displacement, heart sounds, core body position, asynchronous limb
motion, speaking, and biomechanical perturbation.
12. The sensor network of claim 1, wherein the MCU is configured to
perform at least one function of: receiving and processing measured
data of the physiological parameters from the plurality of
spatially separated sensor systems; transmitting the processed data
of the physiological parameters to at least one of a patient
database, a cloud server, and a mobile device; continuously
multi-modal monitoring one or more critical parameters associating
at least one vital sign; and notifying a practitioner or caregiver
when a sensor aberrant signal output condition occurs; and
generating an alarm when an alarming vital sign reading condition
in which the one or more of the critical parameters are out of
pre-defined ranges occurs, and notifying a practitioner or
caregiver of the alarm.
13. The sensor network of claim 12, wherein the one or more
critical parameters are one or more of the heart parameters, brain
activities, temperature, body movements, respiratory parameters,
oxygenation, vocalization parameters, swallow parameters, and blood
pressure and blood flow.
14. The sensor network of claim 1, wherein the MCU is configured to
further perform at least one function of: assessing body pain of
the mammal subject, based on the physiological parameters including
a heart rate, heart rate variability, respiratory rate, respiratory
effort, and crying time, and notifying a practitioner or caregiver
where the pain is assessed; assessing local blood perfusion of the
mammal subject, based on a location specific pulse oximetry derived
from peripheral oxygen saturation (SpO.sub.2) measured by pulse
oximeters of the sensor systems placed on various locations of the
body; and detecting an apneic event when sudden decreases or
cessation of the respiratory rate followed by compensatory
increases in the heart rate and decreases in the SpO.sub.2, and
notifying a practitioner or caregiver when the apneic event occurs,
and vibrating the sensor systems itself to trigger the mammal
subject to change its position or awake from sleep; and localizing
anatomical pathology based on the physiological parameters measured
by the plurality of spatially separated sensor systems placed in
differential locations.
15. The sensor network of claim 1, wherein the MCU comprises a
mobile device for at least one of real-time display of the
physiological parameters, recording of the physiological
parameters, and alarm.
16. The sensor network of claim 15, wherein the mobile device in
bi-directionally wireless communication with the plurality of
spatially separated sensor systems.
17. The sensor network of claim 16, wherein the mobile device is in
wireless communication with the patient database.
18. The sensor network of claim 17, wherein the mobile device is a
hand-held device or a portable device having a graphical user
interface to display the plurality of physiological parameters.
19. The sensor network of claim 1, further comprising a power unit
for wirelessly powering the sensor systems.
20. The sensor network of claim 19, being capable of operating
wirelessly for a period of at least 24 hours without a source of
external power.
21. The sensor network of claim 1, wherein at least one of the
plurality of spatially separated sensor systems further comprises
an actuator configured to generate a force for providing a stimulus
to the mammal subject when a pre-defined trigger signal is
detected.
22. The sensor network of claim 21, wherein the stimulus comprises
gentle vibrations for soothing the mammal subject.
23. The sensor network of claim 21, wherein the actuator is one or
more of an electromechanical motor, a heater, and an electrical
stimulator.
24. The sensor network of claim 1, wherein each of the plurality of
spatially separated sensor systems further comprises: a plurality
of flexible and stretchable interconnects electrically connecting
to a plurality of electronic components including the sensor
member, the SoC and the transceiver; and an elastomeric
encapsulation layer surrounding the electronic components and the
plurality of flexible and stretchable interconnects to form a
tissue-facing surface and an environment-facing surface, wherein
the tissue-facing surface is configured to conform to a skin
surface of the mammal subject.
25. The sensor network of claim 24, wherein the transceiver
comprises a magnetic loop antenna configured to allow simultaneous
wireless data transmission and wireless power harvesting through a
single link.
26. The sensor network of claim 25, wherein the electronic
components of each of the plurality of spatially separated sensor
systems further comprises a battery for provide power to said
sensor system, and the elastomeric encapsulation layer is
configured to electrically isolate the battery from the mammal
subject during use.
27. The sensor network of claim 26, wherein the battery is a
rechargeable battery operably recharged with wireless
recharging.
28. The sensor network of claim 26, wherein the electronic
components of each of the plurality of spatially separated sensor
systems further comprises a failure prevention element that is a
short-circuit protection component or a battery circuit to avoid
battery explosion.
29. The sensor network of claim 26, wherein the encapsulation layer
comprises a flame retardant material.
30. The sensor network of claim 1, wherein the mammal subject is a
human subject or a non-human subject.
31. A method for measuring physiological parameters of a mammal
subject comprising: deploying the sensor network of claim 1,
wherein at least one first sensor system is attached to a central
region of the mammal subject and at least one second sensor system
is attached to an extremity region of the mammal subject such that
the first sensor system and the second sensor system are spatially
separated by a distance; synchronizing the plurality of spatially
separated sensor systems to a common time base; measuring data of
the physiological parameters from the plurality of spatially
separated sensor systems; and wirelessly transmitting the time
synchronized measured physiological parameters.
32. The method of claim 31, wherein said wirelessly transmitting
the time synchronized measured physiological parameters is
performed with the microcontroller unit (MCU) in wireless
communication with the plurality of spatially separated sensor
systems.
33. The method of claim 32, wherein said wirelessly transmitting
the time synchronized measured physiological parameters comprises:
receiving and processing the measured data of the physiological
parameters from the plurality of spatially separated sensor
systems; and transmitting the processed data of the physiological
parameters to at least one of a patient database, a cloud server,
and a mobile device.
34. The method of claim 32, further comprising: associating the
wirelessly transmitted physiological parameters with a unique
patient identifier, thereby identifying the physiological
parameters with the mammal subject in at least one of the patient
database, the cloud server, and the mobile device.
35. The method of claim 32, further comprising identifying a normal
vital sign reading condition, an aberrant sensor output condition,
or an alarming vital sign reading condition, based on the
physiological parameters.
36. The method of claim 35, wherein the aberrant sensor output
condition is one or more of: a lead off state where the
tissue-facing surface of a sensor system is not in intimate contact
with an underlying patient surface; a patient motion artifact; or
an output discrepancy relative to at least two different sensor
systems.
37. The method of claim 36, wherein the aberrant sensor output
condition is identified when at least one vital sign detected from
the first sensor system differs from that detected from the second
sensor by 25% or greater.
38. The method of claim 37, further comprising continuously
multi-modal monitoring one or more critical parameters associating
with the at least one vital sign; and notifying a practitioner or
caregiver when the sensor aberrant signal output condition
occurs.
39. The method of claim 38, further comprising generating an alarm
when the alarming vital sign reading condition in which the one or
more of the critical parameters are out of pre-defined ranges
occurs, and notifying a practitioner or caregiver of the alarm.
40. The method of claim 38, wherein the one or more critical
parameters are one or more of the heart parameters, brain
activities, temperature, body movements, respiratory parameters,
oxygenation, vocalization parameters, swallow parameters, and blood
pressure and blood flow.
41. The method of claim 31, further comprising at least one of:
assessing body pain of the mammal subject, based on the
physiological parameters including a heart rate, heart rate
variability, respiratory rate, respiratory effort, and crying time,
and notifying a practitioner or caregiver where the pain is
assessed; assessing local blood perfusion of the mammal subject,
based on a location specific pulse oximetry derived from peripheral
oxygen saturation (SpO.sub.2) measured by pulse oximeters of the
sensor systems placed on various locations of the body; detecting
an apneic event when sudden decreases or cessation of the
respiratory rate followed by compensatory increases in the heart
rate and decreases in the SpO.sub.2, and notifying a practitioner
or caregiver when the apneic event occurs, and vibrating the sensor
systems itself to trigger the mammal subject to change its position
or awake from sleep; and localizing anatomical pathology based on
the physiological parameters measured by the plurality of spatially
separated sensor systems placed in differential locations.
42. The method of claim 31, further comprising displaying at least
one of the physiological parameters, notifications, and the alarm
in a display having a graphical user interface.
43. The method of claim 42, further comprising securing the display
of the physiological parameters by requiring a secure login before
a user can access the physiological parameters.
44. The method of claim 43, wherein the user is a practitioner or
caregiver, the mammal subject or family member, further comprising
wirelessly communicating between the practitioner or caregiver and
the mammal subject or family member based on the physiological
parameters.
45. The method of claim 43, further comprising securely sending a
command from a remote practitioner or caregiver to a practitioner
or caregiver in proximity to the mammal subject based on the
physiological parameters.
46. The method of claim 31, further comprising actuating an
actuator to generate a force for providing a stimulus to the mammal
subject when a pre-defined trigger signal is detected, wherein the
stimulus comprises gentle vibrations for soothing the mammal
subject.
47. A non-transitory tangible computer-readable medium storing
instructions which, when executed by one or more processors, cause
the method of claim 31 to be performed.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This PCT application claims priority to and the benefit of
U.S. Provisional Patent Application Ser. Nos. 62/753,303,
62/753,453 and 62/753,625, each of which was filed Oct. 31, 2018,
and is incorporated herein by reference in its entirety,
respectively.
[0002] This PCT application is related to a co-pending PCT patent
application, entitled "APPARATUS AND METHOD FOR MEASURING
PHYSIOLOGICAL PARAMETERS OF MAMMAL SUBJECT AND APPLICATIONS OF
SAME", by John A. Rogers et al., with Attorney Docket No.
0116936.213WO2, and a co-pending US patent application entitled
"APPARATUS AND METHOD FOR NON-INVASIVELY MEASURING BLOOD PRESSURE
OF MAMMAL SUBJECT", by John A. Rogers et al., with Attorney Docket
No. 0116936.215US2, each of which is filed on the same day that
this PCT application is filed, and with the same assignee as that
of this application, and is incorporated herein by reference in its
entirety, respectively.
[0003] Some references, which may include patents, patent
applications and various publications, are cited and discussed in
the description of this invention. The citation and/or discussion
of such references is provided merely to clarify the description of
the present invention and is not an admission that any such
reference is "prior art" to the invention described herein. All
references cited and discussed in this specification are
incorporated herein by reference in their entireties and to the
same extent as if each reference was individually incorporated by
reference.
FIELD OF THE INVENTION
[0004] The invention relates generally to healthcare, and more
particularly, to sensor network for measuring physiological
parameters of mammal subject and applications of the same.
BACKGROUND OF THE INVENTION
[0005] The background description provided herein is for the
purpose of generally presenting the context of the invention. The
subject matter discussed in the background of the invention section
should not be assumed to be prior art merely as a result of its
mention in the background of the invention section. Similarly, a
problem mentioned in the background of the invention section or
associated with the subject matter of the background of the
invention section should not be assumed to have been previously
recognized in the prior art. The subject matter in the background
of the invention section merely represents different approaches,
which in and of themselves may also be inventions. Work of the
presently named inventors, to the extent it is described in the
background of the invention section, as well as aspects of the
description that may not otherwise qualify as prior art at the time
of filing, are neither expressly nor impliedly admitted as prior
art against the invention.
[0006] Every year, 300,000 neonates are admitted to the neonatal
care unit (NICU) in the U.S. The Global Fetal and Neonatal Care
Equipment market is expected to grow from $7.32 billion in 2016 to
reach $11.86 billion by 2022. Vital sign monitoring systems,
however, have largely remained locked in time since the 1970s.
Large base units with extensive wires are still attached to
numerous electrodes.
[0007] Continuous monitoring of vital signs in the NICU is
essential to the survival of critically-ill neonates. Conventional
medical platforms in the NICU fail, however, to offer a safe,
patient-centric mode of operation, largely due to the use of
hard-wired, rigid interfaces to the neonate's fragile,
under-developed skin. Thus, continuous monitoring of vital signs
for critical care applications in maternal/fetal and neonatal
health requires new technology able to meet unique demands. Small
yet adaptable form factors are needed with low skin-device
interface stressors. Higher noise to signal ratios require
specialized processing and algorithms able to faithfully collect
vital signs even during periods of high motion artifact.
[0008] Therefore, a heretofore unaddressed need exists in the art
to address the aforementioned deficiencies and inadequacies.
SUMMARY OF THE INVENTION
[0009] One aspect of the invention is to provide a new class of
wireless wearable sensors capable of re-capitulating standard of
care monitoring systems, with relevance for deployment in pediatric
health, in a highly networked and synchronized fashion. These
wireless wearable sensors are in a networked configuration to
facilitate real time data processing, analytics, and safety
features that meet the rigorous demands of clinical care. The
sensor network has advanced monitoring capabilities and greater
safety features, and is applicable to both low-resource settings
where wireless vital sign monitoring systems have not penetrated
into neonatal care as well as high-resource settings where the
instant systems represent the cutting edge, next generation systems
for neonatal monitoring.
[0010] In one aspect, the invention relates to a sensor network for
measuring physiological parameters of a mammal subject. The
physiological parameters include, but are not limited to, one or
more of heart activities including a stroke volume and ejection
fraction, oxygenation level, temperature, skin temperature
differentials, body movement, body position, breathing parameters,
blood pressure, crying time, crying frequency, swallow count,
swallow frequency, chest wall displacement, heart sounds, core body
position, asynchronous limb motion, speaking, and biomechanical
perturbation. The mammal subject can be a living human subject or a
living non-human subject. In certain embodiments, physiological
parameters of neonates or infants are monitored and measured. It
should be appreciated to one skilled in the art that physiological
parameters of children or adults can also be monitored and measured
in practice the invention.
[0011] In one embodiment, the sensor network includes a plurality
of spatially separated sensor systems that is time-synchronized to
each other. Each of the plurality of spatially separated sensor
systems is attached to a respective position of the mammal subject
and includes a sensor member for measuring at least one
physiological parameter, a system on a chip (SoC) having a
microprocessor coupled to the sensor member for receiving data from
the sensor member and processing the received data, and a
transceiver coupled to the SoC for wireless data transmission and
wireless power harvesting. The sensor network also includes a
microcontroller unit (MCU) adapted in wireless communication with
the plurality of spatially separated sensor systems for wirelessly
transmitting data to and from the plurality of spatially separated
sensor systems.
[0012] In one embodiment, each two adjacent sensor systems are
spatially separated by a respective distance that is adjustable
between a minimal distance and a maximal distance.
[0013] In one embodiment, the plurality of spatially separated
sensor systems comprises a first sensor system configured to attach
to a central region of the mammal subject and a second sensor
system configured to attach to an extremity region of the mammal
subject. In one embodiment, the central region comprises one or
more of a chest region, a neck region including a suprasternal
notch area, and a head region including a forehead region or an
anterior fontanelle region of the mammal subject. The extremity
region comprises one or more of a limb region, a foot region, a
hand region, a toenail region, and a fingernail region of the
mammal subject.
[0014] In one embodiment, the sensor member of the first sensor
system comprises at least two electrodes spatially apart from each
other for electrocardiogram (ECG) generation.
[0015] In one embodiment, the sensor member of the second sensor
system comprises a photoplethysmogram (PPG) sensor comprising an
optical source and an optical detector located within a sensor
footprint.
[0016] In one embodiment, each sensor member of the first sensor
system and the second sensor system further comprises one or more
of an accelerometer for measuring at least one of a position and a
movement; an inertial measurement unit (IMU) for measuring at least
one of a movement, a force, an angular rate, and an orientation;
and a temperature sensor for measuring temperature.
[0017] In one embodiment, the accelerometer or the IMU is used to
measure at least one of seismocardiography (SCG) and a respiratory
rate.
[0018] In one embodiment, the accelerometer or the IMU is used with
a motion artifact module to identify a vital sign as subject to
motion artifact and to correct of motion artifact.
[0019] In one embodiment, each sensor member of the first sensor
system and the second sensor system comprises one or more of an ECG
sensor, an EKG sensor, a pulse oximeter sensor, a temperature
sensor, a blood pressure sensor, an accelerometer, or an acoustic
sensor.
[0020] In one embodiment, the MCU is configured to perform at least
one function of receiving and processing measured data of the
physiological parameters from the plurality of spatially separated
sensor systems; transmitting the processed data of the
physiological parameters to at least one of a patient database, a
cloud server, and a mobile device; continuously multi-modal
monitoring one or more critical parameters associating at least one
vital sign; and notifying a practitioner or caregiver when a sensor
aberrant signal output condition occurs; and generating an alarm
when an alarming vital sign reading condition in which the one or
more of the critical parameters are out of pre-defined ranges
occurs, and notifying a practitioner or caregiver of the alarm. In
one embodiment, the one or more critical parameters are one or more
of the heart parameters, brain activities, temperature, body
movements, respiratory parameters, oxygenation, vocalization
parameters, swallow parameters, and blood pressure and blood
flow.
[0021] In one embodiment, the MCU is configured to further perform
at least one function of assessing body pain of the mammal subject,
based on the physiological parameters including a heart rate, heart
rate variability, respiratory rate, respiratory effort, and crying
time, and notifying a practitioner or caregiver where the pain is
assessed; assessing local blood perfusion of the mammal subject,
based on a location specific pulse oximetry derived from peripheral
oxygen saturation (SpO.sub.2) measured by pulse oximeters of the
sensor systems placed on various locations of the body; detecting
an apneic event when sudden decreases or cessation of the
respiratory rate followed by compensatory increases in the heart
rate and decreases in the SpO.sub.2, and notifying a practitioner
or caregiver when the apneic event occurs, and vibrating the sensor
systems itself to trigger the mammal subject to change its position
or awake from sleep; and localizing anatomical pathology based on
the physiological parameters measured by the plurality of spatially
separated sensor systems placed in differential locations.
[0022] In one embodiment, the MCU comprises a mobile device for at
least one of real-time display of the physiological parameters,
recording of the physiological parameters, and alarm.
[0023] In one embodiment, the mobile device in bi-directionally
wireless communication with the plurality of spatially separated
sensor systems. In one embodiment, the mobile device is in wireless
communication with the patient database. In one embodiment, the
mobile device is a hand-held device or a portable device having a
graphical user interface to display the plurality of physiological
parameters.
[0024] In one embodiment, the sensor network further comprises a
power unit for wirelessly powering the sensor systems. In one
embodiment, the sensor network is capable of operating wirelessly
for a period of at least 24 hours without a source of external
power.
[0025] In one embodiment, at least one of the plurality of
spatially separated sensor systems further comprises an actuator
configured to generate a force for providing a stimulus to the
mammal subject when a pre-defined trigger signal is detected. In
one embodiment, the stimulus comprises gentle vibrations for
soothing the mammal subject.
[0026] In one embodiment, the actuator is one or more of an
electromechanical motor, a heater, and an electrical
stimulator.
[0027] In one embodiment, each of the plurality of spatially
separated sensor systems further comprises a plurality of flexible
and stretchable interconnects electrically connecting to a
plurality of electronic components including the sensor member, the
SoC and the transceiver; and an elastomeric encapsulation layer
surrounding the electronic components and the plurality of flexible
and stretchable interconnects to form a tissue-facing surface and
an environment-facing surface, wherein the tissue-facing surface is
configured to conform to a skin surface of the mammal subject. In
one embodiment, the encapsulation layer comprises a flame retardant
material.
[0028] In one embodiment, the transceiver comprises a magnetic loop
antenna configured to allow simultaneous wireless data transmission
and wireless power harvesting through a single link.
[0029] In one embodiment, the electronic components of each of the
plurality of spatially separated sensor systems further comprises a
battery for provide power to said sensor system, and the
elastomeric encapsulation layer is configured to electrically
isolate the battery from the mammal subject during use. In one
embodiment, the battery is a rechargeable battery operably
recharged with wireless recharging.
[0030] In one embodiment, the electronic components of each of the
plurality of spatially separated sensor systems further comprises a
failure prevention element that is a short-circuit protection
component or a battery circuit to avoid battery explosion.
[0031] In another aspect, the invention relates to a method for
measuring physiological parameters of a mammal subject. In one
embodiment, the method includes deploying the sensor network as
disclosed above; synchronizing the plurality of spatially separated
sensor systems to a common time base; measuring data of the
physiological parameters from the plurality of spatially separated
sensor systems; and wirelessly transmitting the time synchronized
measured physiological parameters. Said deploying the sensor
network including respectively attaching at least one first sensor
system to a central region of the mammal subject and at least one
second sensor system to an extremity region of the mammal subject
such that the first sensor system and the second sensor system are
spatially separated by a distance.
[0032] In one embodiment, said wirelessly transmitting the time
synchronized measured physiological parameters is performed with
the MCU in wireless communication with the plurality of spatially
separated sensor systems.
[0033] In one embodiment, said wirelessly transmitting the time
synchronized measured physiological parameters comprises receiving
and processing the measured data of the physiological parameters
from the plurality of spatially separated sensor systems; and
transmitting the processed data of the physiological parameters to
at least one of a patient database, a cloud server, and a mobile
device.
[0034] In one embodiment, the method further comprises associating
the wirelessly transmitted physiological parameters with a unique
patient identifier, thereby identifying the physiological
parameters with the mammal subject in at least one of the patient
database, the cloud server, and the mobile device.
[0035] In one embodiment, the method further comprises identifying
a normal vital sign reading condition, an aberrant sensor output
condition, or an alarming vital sign reading condition, based on
the physiological parameters. In one embodiment, the aberrant
sensor output condition is one or more of a lead off state where
the tissue-facing surface of a sensor system is not in intimate
contact with an underlying patient surface; a patient motion
artifact; or an output discrepancy relative to at least two
different sensor systems. In one embodiment, the aberrant sensor
output condition is identified when at least one vital sign
detected from the first sensor system differs from that detected
from the second sensor by 25% or greater.
[0036] In one embodiment, the method further comprises continuously
multi-modal monitoring one or more critical parameters associating
with the at least one vital sign; and notifying a practitioner or
caregiver when the sensor aberrant signal output condition
occurs.
[0037] In one embodiment, the method further comprises generating
an alarm when the alarming vital sign reading condition in which
the one or more of the critical parameters are out of pre-defined
ranges occurs, and notifying a practitioner or caregiver of the
alarm.
[0038] In one embodiment, the one or more critical parameters are
one or more of the heart parameters, brain activities, temperature,
body movements, respiratory parameters, oxygenation, vocalization
parameters, swallow parameters, and blood pressure and blood
flow.
[0039] In one embodiment, the method further comprises at least one
of assessing body pain of the mammal subject, based on the
physiological parameters including a heart rate, heart rate
variability, respiratory rate, respiratory effort, and crying time,
and notifying a practitioner or caregiver where the pain is
assessed; assessing local blood perfusion of the mammal subject,
based on a location specific pulse oximetry derived from the
SpO.sub.2 measured by pulse oximeters of the sensor systems placed
on various locations of the body; detecting an apneic event when
sudden decreases or cessation of the respiratory rate followed by
compensatory increases in the heart rate and decreases in the
SpO.sub.2, and notifying a practitioner or caregiver when the
apneic event occurs, and vibrating the sensor systems itself to
trigger the mammal subject to change its position or awake from
sleep; and localizing anatomical pathology based on the
physiological parameters measured by the plurality of spatially
separated sensor systems placed in differential locations.
[0040] In one embodiment, the method further comprises displaying
at least one of the physiological parameters, notifications, and
the alarm in a display having a graphical user interface.
[0041] In one embodiment, the method further comprises securing the
display of the physiological parameters by requiring a secure login
before a user can access the physiological parameters.
[0042] In one embodiment, the user is a practitioner or caregiver,
the mammal subject or family member, and the method further
comprises wirelessly communicating between the practitioner or
caregiver and the mammal subject or family member based on the
physiological parameters.
[0043] In one embodiment, the method further comprises securely
sending a command from a remote practitioner or caregiver to a
practitioner or caregiver in proximity to the mammal subject based
on the physiological parameters.
[0044] In one embodiment, the method further comprises actuating an
actuator to generate a force for providing a stimulus to the mammal
subject when a pre-defined trigger signal is detected. In one
embodiment, the stimulus comprises gentle vibrations for soothing
the mammal subject.
[0045] In yet another aspect, the invention relates to a
non-transitory tangible computer-readable medium storing
instructions which, when executed by one or more processors, cause
the above-disclosed method to be performed.
[0046] These and other aspects of the invention will become
apparent from the following description of the preferred embodiment
taken in conjunction with the following drawings, although
variations and modifications therein may be affected without
departing from the spirit and scope of the novel concepts of the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0047] The following drawings form part of the present
specification and are included to further demonstrate certain
aspects of the invention. The invention may be better understood by
reference to one or more of these drawings in combination with the
detailed description of specific embodiments presented herein. The
drawings described below are for illustration purposes only. The
drawings are not intended to limit the scope of the present
teachings in any way.
[0048] FIG. 1A schematically shows a functional block diagram of a
sensor network according to certain embodiments of the present
invention.
[0049] FIG. 1B schematically shows a deployment of a sensor network
according to certain embodiments of the present invention. The
sensor system in the upper left panel is configured to attach to a
torso region, such as the chest, while the sensor system in the
upper right panel is configured to attach to an appendage, such as
a foot, as illustrated in the bottom left and bottom right panels,
respectively.
[0050] FIGS. 2A-2H show schematic illustrations of ultra-thin,
skin-like wireless sensor systems used in a sensor network,
according to embodiments of the invention. FIG. 2A is a functional
block diagram showing analog front end and electronic components of
each EES, components of the near-field communication (NFC) system
on a chip (SoC) including microcontroller, general-purpose
input/output (GPIO), and radio interface, with a host reader
platform that includes an NFC reader module and a Bluetooth low
energy (BLE) interface with circular buffer. FIG. 2B shows a
functional block diagram of the two sensor systems according to
another embodiment of the invention. The power management unit
involves dual power operation mode from primary wireless power
transfer and the secondary battery for portability. The ECG EES
includes optional electrode for fECG measurement and 6 axial
inertial measurement unit (IMU) for seismocardiography (SCG) and
respiratory rate measurement on top of ECG analog front end. The
PPG EES includes the pulse oximetry analog front end and 6 axial
IMU for motion artifact reduction algorithm. Each individual unit
is controlled by BLE SoC. FIG. 2C is a schematic of a sensor system
configured to attach to the torso, such as a chest, according to
one embodiment of the invention. The sensor system is stretchable
and foldable, as illustrated in the top panels. The electrical
components and layout are illustrated in the bottom panel,
including the components providing a networked and wireless
platform (including a power unit, a memory unit, a temperature
unit, an ECG unit, a BLE SoC). FIG. 2D shows a sensor system
configured to attach on an extremity, such as a foot, leg, hand,
arm finger, toe or nail, such as by a wrapping-type mechanism to
secure the main circuit components with a mechanically decoupled
sensor system connected thereto, according to one embodiment of the
invention. The sensor system is stretchable and foldable, as
illustrated in the top panels. The electrical components (including
power unit, memory unit, temperature unit, PPG sensor, Bluetooth
low energy (BLE)) and layout are illustrated in the bottom panel,
including the components to provide a networked and wireless
platform. The sensor portion may be aligned in a different
direction, such as an orthogonal direction relative to the main
circuit components. In this manner, the main circuit components may
wrap around the foot, with the sensor portion independently
mountable, such as to a nail region. In one embodiment, the PPG
sensor system for measuring oxygenation with a sensor having an LED
unit. The main circuit component, including a microprocessor and a
wireless transmitter are aligned in one direction, referred to as a
wrap direction. The LED unit extends at a different direction from
the wrap direction. In this manner, the main circuit component can
be wrapped around an extremity without any adhesive, such as around
an ankle. The active sensor portion can independently be attached
to a desired location, such as a foot or a toenail. In this manner,
only a small footprint of the total device needs to be reliably
affixed to the patient, and can even be affixed with an adhesive to
a surface that can more readily withstand the adhesive and
corresponding removal, such as a nail. FIG. 2E is a schematic
representation of PPG device for measuring oxygenation with a
sensor having an LED unit, according to one embodiment of the
invention. The main circuit component, including a microprocessor
and a wireless transmitter are aligned in one direction, referred
to as a wrap direction. The LED unit extends at a different
direction from the wrap direction. In this manner, the main circuit
component can be wrapped around an extremity without any adhesive,
such as around an ankle. The active sensor portion can
independently be mounted at a desired location, such as a foot or a
toenail. In this manner, only a small footprint of the total device
needs to be reliably affixed to the patient, and can even be
affixed with an adhesive to a surface that can more readily
withstand the adhesive and corresponding removal, such as a nail.
FIG. 2F is a schematic diagram of an ECG sensor system that
measures electric potential, temperature, position and motion that
are wirelessly transmitted to a microprocessor, illustrated as part
of an MCU, according to one embodiment of the invention. FIG. 2G is
a schematic diagram of a PPG sensor system to measure oxygen and
that measures also temperature, that are transmitted to a
microprocessor, illustrated as part of an MCU, according to one
embodiment of the invention. FIG. 2H shows an exemplary NFC Reader
IC, illustrating MCU, IC and antenna, according to one embodiment
of the invention.
[0051] FIG. 3 is an illustration of two sensor systems (chest unit
and foot unit) of a sensor network that support continuous 24/7 use
without external wires and, at most, a gentle adhesive such as a
hydrogel, according to one embodiment of the invention.
[0052] FIG. 4 shows a PPG sensor system configured to conformally
wrap around an appendage (to panel), with the sensor wrapped around
a doll and a neonate foot in the respective bottom panels,
according to one embodiment of the invention.
[0053] FIG. 5 shows a flowchart of a method of monitoring
physiological parameters of a mammal subject according to certain
embodiments of the invention.
[0054] FIG. 6 shows schematically a flowchart of the onboard
software operation of the sensors of the sensor network according
to certain embodiments of the invention.
[0055] FIG. 7 shows schematically an illustration of general
sensing, storage and telemedical applications of a sensor network
according to certain embodiments of the invention.
[0056] FIGS. 8A-8C illustrate the use of an ECG sensor for
respiratory rate (RR) estimation according to certain embodiments
of the invention. FIG. 8A shows an algorithm using an ECG sensor
for respiratory rate (RR) estimation. FIG. 8B illustrates the RR
estimation using the algorithm shown in FIG. 8A, based on the ECG
signal measured by the ECG sensor. FIG. 8C shows a plot of the
actual count compared to the ECG EES.
[0057] FIGS. 9A-9B illustrates the use of chest wall movements,
measured by an accelerometer, for RR estimation according to
certain embodiments of the invention. FIG. 9A shows an algorithm
using chest wall movements for the RR estimation. FIG. 9B
illustrates the RR estimation using the algorithm shown in FIG. 9A,
based on the chest wall movements measured by the
accelerometer.
[0058] FIG. 10 shows signal processing algorithms of continuous
wavelet transform (CWT) DST for pulse oximetry according to certain
embodiments of the invention.
[0059] FIGS. 11A and 11B illustrate SpO.sub.2 determination for a
clean signal (no motion artifact) and a noisy signal (motion
contaminated signal), respectively, according to certain
embodiments of the invention.
[0060] FIG. 12 shows that, for heart rate, the mean difference from
the experimental system compared to standard-of-care system was
-0.47 beats per minute aggregated across 18 subjects, according to
certain embodiments of the invention. The standard deviation of the
mean difference was 3.0 beats per minute. Thus, 95% of the data
fall within a discrepancy less than 6.0 beats per minute. The
agreement of the experimental wireless system remained comparable
at lower heart rates (<100 beats per minute) and higher heart
rates (>170 beats per minute).
[0061] FIG. 13 shows that, for blood oxygenation, the mean
difference was 0.11% and the standard deviation of the mean
difference was 1.8% between the experimental system and the
standard-of-care system aggregated across 16 subjects, according to
certain embodiments of the invention. Thus, 95% of the data fall
within a discrepancy less than 3.6% blood oxygenation. The
agreement of the experimental wireless system remained comparable
at both lower blood oxygenation (<90%) as well as higher blood
oxygenation (>96%). Two subjects had intravenous lines or other
medically necessary equipment on both lower extremities and
excluded.
[0062] FIG. 14 shows that, for respiratory rate, the mean
differences was -2.0 breaths per minute with a standard deviation
of mean differences of 8.7 breaths per minute between the
experimental system and the reference system according to certain
embodiments of the invention. The higher variation for respiratory
rate may relate to differences in the measuring modality of
respiratory rate. Respiratory rate derived by the experimental
system is through the ECG while the reference Phillips monitor
utilizes thoracic impedance pneumography). Similar performance is
noted for measurements across low and high respiration rates
(<30 and >70 breaths per minute).
[0063] FIG. 15 shows the heart rate determined by a sensor network
according to certain embodiments of the invention, illustrating the
equivalent performance to an FDA-approved device.
[0064] FIG. 16 shows comparisons of a PPG sensor compared to a
gold-standard system, according to certain embodiments of the
invention.
[0065] FIG. 17 shows a neonatal forehead measurement for SpO.sub.2
measurements, according to certain embodiments of the
invention.
[0066] FIG. 18A are photographs of skin surface before placement
(top panels) and for sensor placement (bottom panels) for chest
attached (left panels) and foot attached (right panels), according
to certain embodiments of the invention.
[0067] FIG. 18B shows skin after removal (top panels) and 30
minutes after removal (bottom panels), according to certain
embodiments of the invention.
[0068] FIG. 19 shows thermal images of the chest region after 24
hours of sensor mounting immediately before (top panel) and after
removal (bottom panel) revealing no heating of the skin and no heat
generation, according to certain embodiments of the invention.
[0069] FIG. 20 illustrates different temperature sensor locations
in a sensor network according to certain embodiments of the
invention.
[0070] FIG. 21 is a graph of temperature calibration curves for a
chest (top panel) and foot (bottom panel) unit according to certain
embodiments of the invention.
[0071] FIG. 22 illustrates good agreement and correlation with the
instant temperature sensors and a gold standard temperature sensor,
according to certain embodiments of the invention.
[0072] FIG. 23 illustrates the differences in temperature
measurement for the sensors illustrated in FIG. 21 compared to core
temperature (top panel) and compared to infrared temperature
measurement (bottom panel) according to certain embodiments of the
invention.
[0073] FIG. 24 is a graphical representation of three-dimensional
sensor position (x, y, z) for a sleeping, held in arms and held
against body (kangaroo mother care or "KMC"), according to certain
embodiments of the invention.
[0074] FIG. 25 shows the average (x, y, z) locations determined by
a sensor system having an accelerometer, for an infant in different
positions reflected by the photographs, according to certain
embodiments of the invention.
[0075] FIG. 26 is a graphical representation of the location
results for a sleeping, feeding, holding and KMC position according
to certain embodiments of the invention.
[0076] FIG. 27 is a summary of the measure (x, y, z) positions
according to certain embodiments of the invention.
[0077] FIG. 28 is an accelerometer output for burping of a neonate
in a clinical study according to certain embodiments of the
invention.
[0078] FIG. 29 is a summary of an in-lab simulation showing x, y, z
position over time, with a KMC and tilt maneuver, according to
certain embodiments of the invention.
[0079] FIGS. 30A-30B summarize the KMC accelerometer sensor
measurement and processing, respectively, according to certain
embodiments of the invention. Various learning algorithms, such as
supervised and unsupervised learning, assist in obtaining and
classifying the data.
[0080] FIG. 31 illustrates data labeling for posture, tilt and
movement based on an accelerometer sensor system, according to
certain embodiments of the invention.
[0081] FIGS. 32A-32B and 33-38 illustrate the powerful use of a
remote receiver, where a GUI can provide easy to understand
monitoring to remote caregiver or family member, according to
certain embodiments of the invention.
[0082] FIG. 39 shows a flowchart summarizing various telemedical
applications of the sensor network system, according to certain
embodiments of the invention. Specifically, the sensor can be
viewed by both the neonate's caregivers as well as their providers.
The availability of skilled neonatologists trained in critical care
is limited in developing countries or rural communities. The
wearable sensors in this disclosure can also enable secure
physician/clinician view allowing for eNICU care at a distance.
[0083] FIG. 40 is a flowchart summary illustrating the benefits of
measuring a physiological parameter with at least three different
sensors according to certain embodiments of the invention. If all
sensors obtain a similar reading that is out of a specified normal
range for the parameter, a caregiver is notified. If one sensor is
out of a defined agreement range (e.g., +/-10%, or a
user-determined range that may be relevant for the specific sensors
being used and vital sign being measure), a notification is sent of
an aberrant signal for that sensor so that remedial action can be
taken. Alternatively, if all sensors are in agreement that the
parameter is outside a "normal" range, the clinician may be
notified so that immediate intervention/assessment is made. Of
course, even while this is occurring, the sensors may be
continuously in operation providing parameter measurements. For
normal operating conditions, the dashed arrows reflect the sensor
network simply continues normal operation.
[0084] FIG. 41 is a flowchart summary similar to FIG. 40, but with
an additional Sensor 4 accelerometer that is used to compensate and
correct for motion artifacts, thereby further increasing sensor
accuracy and reliability.
[0085] FIG. 42 is a schematic illustration of the wireless
communication and a Bluetooth time synchronization to provide
time-synchronized sensors, according to certain embodiments of the
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0086] The present invention will now be described more fully
hereinafter with reference to the accompanying drawings, in which
exemplary embodiments of the present invention are shown. The
present invention may, however, be embodied in many different forms
and should not be construed as limited to the embodiments set forth
herein. Rather, these embodiments are provided so that this
disclosure will be thorough and complete, and will fully convey the
scope of the invention to those skilled in the art. Like reference
numerals refer to like elements throughout.
[0087] The terms used in this specification generally have their
ordinary meanings in the art, within the context of the invention,
and in the specific context where each term is used. Certain terms
that are used to describe the invention are discussed below, or
elsewhere in the specification, to provide additional guidance to
the practitioner regarding the description of the invention. For
convenience, certain terms may be highlighted, for example using
italics and/or quotation marks. The use of highlighting and/or
capital letters has no influence on the scope and meaning of a
term; the scope and meaning of a term are the same, in the same
context, whether or not it is highlighted and/or in capital
letters. It will be appreciated that the same thing can be said in
more than one way. Consequently, alternative language and synonyms
may be used for any one or more of the terms discussed herein, nor
is any special significance to be placed upon whether or not a term
is elaborated or discussed herein. Synonyms for certain terms are
provided. A recital of one or more synonyms does not exclude the
use of other synonyms. The use of examples anywhere in this
specification, including examples of any terms discussed herein, is
illustrative only and in no way limits the scope and meaning of the
invention or of any exemplified term. Likewise, the invention is
not limited to various embodiments given in this specification.
[0088] It will be understood that, although the terms first,
second, third, etc. may be used herein to describe various
elements, components, regions, layers and/or sections, these
elements, components, regions, layers and/or sections should not be
limited by these terms. These terms are only used to distinguish
one element, component, region, layer or section from another
element, component, region, layer or section. Thus, a first
element, component, region, layer or section discussed below can be
termed a second element, component, region, layer or section
without departing from the teachings of the present invention.
[0089] It will be understood that, as used in the description
herein and throughout the claims that follow, the meaning of "a",
"an", and "the" includes plural reference unless the context
clearly dictates otherwise. Also, it will be understood that when
an element is referred to as being "on," "attached" to, "connected"
to, "coupled" with, "contacting," etc., another element, it can be
directly on, attached to, connected to, coupled with or contacting
the other element or intervening elements may also be present. In
contrast, when an element is referred to as being, for example,
"directly on," "directly attached" to, "directly connected" to,
"directly coupled" with or "directly contacting" another element,
there are no intervening elements present. It will also be
appreciated by those of skill in the art that references to a
structure or feature that is disposed "adjacent" to another feature
may have portions that overlap or underlie the adjacent
feature.
[0090] It will be further understood that the terms "comprises"
and/or "comprising," or "includes" and/or "including" or "has"
and/or "having" when used in this specification specify the
presence of stated features, regions, integers, steps, operations,
elements, and/or components, but do not preclude the presence or
addition of one or more other features, regions, integers, steps,
operations, elements, components, and/or groups thereof.
[0091] Furthermore, relative terms, such as "lower" or "bottom" and
"upper" or "top," may be used herein to describe one element's
relationship to another element as illustrated in the figures. It
will be understood that relative terms are intended to encompass
different orientations of the device in addition to the orientation
shown in the figures. For example, if the device in one of the
figures is turned over, elements described as being on the "lower"
side of other elements would then be oriented on the "upper" sides
of the other elements. The exemplary term "lower" can, therefore,
encompass both an orientation of lower and upper, depending on the
particular orientation of the figure. Similarly, if the device in
one of the figures is turned over, elements described as "below" or
"beneath" other elements would then be oriented "above" the other
elements. The exemplary terms "below" or "beneath" can, therefore,
encompass both an orientation of above and below.
[0092] Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which the present
invention belongs. It will be further understood that terms, such
as those defined in commonly used dictionaries, should be
interpreted as having a meaning that is consistent with their
meaning in the context of the relevant art and the present
disclosure, and will not be interpreted in an idealized or overly
formal sense unless expressly so defined herein.
[0093] As used in this disclosure, "around", "about",
"approximately" or "substantially" shall generally mean within 20
percent, preferably within 10 percent, and more preferably within 5
percent of a given value or range. Numerical quantities given
herein are approximate, meaning that the term "around", "about",
"approximately" or "substantially" can be inferred if not expressly
stated.
[0094] As used in this disclosure, the phrase "at least one of A,
B, and C" should be construed to mean a logical (A or B or C),
using a non-exclusive logical OR. As used herein, the term "and/or"
includes any and all combinations of one or more of the associated
listed items.
[0095] As used in this disclosure, the term "spatially separated"
refers to two different locations on skin, wherein the two sensor
systems disposed on those locations are not in physical contact.
For example, one sensor system may be on the torso, and another
sensor system on the foot.
[0096] As used in this disclosure, the term "mammal subject" refers
to a living human subject or a living non-human subject. For the
purpose of illustration of the invention, the apparatus and method
are applied to monitor and/or measure physiological parameters of
neonates or infants. It should be appreciated to one skilled in the
art that the apparatus can also be applied to monitor and/or
measure physiological parameters of children or adults in practice
the invention.
[0097] The description below is merely illustrative in nature and
is in no way intended to limit the invention, its application, or
uses. The broad teachings of the invention can be implemented in a
variety of forms. Therefore, while this invention includes
particular examples, the true scope of the invention should not be
so limited since other modifications will become apparent upon a
study of the drawings, the specification, and the following claims.
For purposes of clarity, the same reference numbers will be used in
the drawings to identify similar elements. It should be understood
that one or more steps within a method may be executed in different
order (or concurrently) without altering the principles of the
invention.
[0098] To address the aforementioned deficiencies and inadequacies,
the invention in one aspect discloses a new class of wireless
wearable sensors capable of re-capitulating standard of care
monitoring systems, with relevance for deployment in pediatric
health, in a highly networked and synchronized fashion. These
wireless wearable sensors are in a networked configuration to
facilitate real time data processing, analytics, and safety
features that meet the rigorous demands of clinical care. The
sensor network has advanced monitoring capabilities and greater
safety features, and is applicable to both low-resource settings
where wireless vital sign monitoring systems have not penetrated
into neonatal care as well as high-resource settings where the
instant systems represent the cutting edge, next generation systems
for neonatal monitoring.
[0099] In one aspect, the invention relates to a sensor network for
or non-invasively and continuously measuring physiological
parameters of a mammal subject. Physiological parameters that can
be measured include, but are not limited to, one or more of heart
activities including a stroke volume and ejection fraction,
oxygenation level, temperature, skin temperature differentials,
body movement, body position, breathing parameters,
ballistocardiography, respiratory effort, blood pressure, crying
time, crying frequency, swallow count, swallow frequency, chest
wall displacement, heart sounds, core body position, asynchronous
limb motion, speaking, and biomechanical perturbation.
[0100] In certain embodiments, the sensor network includes a
plurality of spatially separated sensor systems that is
time-synchronized to each other. Each of the plurality of spatially
separated sensor systems is attached to a respective position of
the mammal subject and includes a sensor member for measuring at
least one physiological parameter, a system on a chip (SoC) having
a microprocessor coupled to the sensor member for receiving data
from the sensor member and processing the received data, and a
transceiver coupled to the SoC for wireless data transmission and
wireless power harvesting. The sensor network also includes a
microcontroller unit (MCU) adapted in bidirectional wireless
communication with the plurality of spatially separated sensor
systems for wirelessly transmitting data to and from the plurality
of spatially separated sensor systems.
[0101] FIG. 1A schematically shows a functional block diagram of a
sensor network according to one embodiment of the present
invention. In the exemplary embodiments, the sensor network 100
includes first sensor system(s) 110 and second sensor system(s) 150
that are time-synchronized to each other, and a microcontroller
unit (MCU) (alternatively, a reader system) 190 adapted in wireless
communication with the first sensor system 110 and the second
sensor system 150. In certain embodiments, each of the first sensor
system 110 and the second sensor system 150 is in wireless
communication with the MCU 190 via a wireless transmission
protocol, such as a near field communication (NFC) protocol, or
Bluetooth protocol. Specifically, the term "time-synchronized" (or
"time-synced") refers to measurement of a parameter by different
sensors, at different locations, that are synchronized in time to
allow for measurement of novel physiological parameters.
[0102] In certain embodiments, each of the first sensor system 110
and the second sensor system 150 is an epidermal electronic system
(EES). For example, the first sensor system 110 is configured to
attach to a central region, while the second sensor system 150 is
configured to attach to an extremity region of the mammal subject.
The central region includes one or more of a chest region, a neck
region including a suprasternal notch area, and a head region
including a forehead region or an anterior fontanelle region of the
mammal subject. The extremity region includes one or more of a limb
region, a foot region, a hand region, a toenail region, and a
fingernail region of the mammal subject.
[0103] In certain embodiments, the first sensor system 110 is a
conformable torso sensor system configured to attach and conform to
a torso region of the mammal subject for recording
electrocardiogram (ECG) data and skin temperature; and the second
sensor system 150 is a conformable extremity sensor system
configured to attach and conform to a limb or appendage region of
the mammal subject for recording photoplethysmogram (PPG) data and
skin temperature. In other words, the first sensor system 110 can
be an electrocardiography (ECG), and the second sensor system 150
can be a PPG sensor system. As shown in FIGS. 1A and 1B, the torso
sensor system 110 and the extremity sensor system 150 are operably
attached to a first region 410, which is, for example, a torso
region such as the chest, and a second region 420, which is, for
example, a limb region 420 such as a foot, respectively, of the
neonate so that the torso sensor system 110 and the extremity
sensor system 150 are spatially separated by a distance L. The
distance L between the torso sensor system 110 and the extremity
sensor system 150 is adjustable between a minimal distance and a
maximal distance.
[0104] In certain embodiments, each of the torso sensor system 110
and the extremity sensor system 150 includes a sensor member
(circuit) having one or more sensors that are used to detect a
vital sign of the mammal subject, and then to generate one or more
corresponding physiological parameters, an SoC having a
microprocessor coupled to the sensor member (circuit) for receiving
data from the sensor member and processing the received data, and a
transceiver coupled to the SoC for wireless data transmission and
wireless power harvesting. The sensors may be various types of
sensors for detecting the vital sign as a signal, and the signal
can be, for example, an electrical signal related to at least one
of ECG and electromyography (EMG) technology; a mechanical signal
related to movement, respiration and arterial tonometry; an
acoustic signal related to vocal cord vocalization and heart sound;
and an optical signal related to blood oxygenation, and so on. In
certain embodiments, each sensor member of the first sensor system
110 and the second sensor system 150 comprises one or more of an
ECG sensor, an EKG sensor, a pulse oximeter sensor, a temperature
sensor, a blood pressure sensor, an accelerometer, and an acoustic
sensor.
[0105] Referring to FIG. 2A, in one embodiment, the sensor circuit
(member) 123 of the torso sensor system 110 includes, but is not
limited to, two electrodes 121 and 122 spatially separated from
each other for ECG generation. The electrodes 121 and 122 can be
either mesh electrodes or solid electrodes. The sensor member 123
also includes, but is not limited to, an instrumentation amplifier
(e.g., Inst. Amp) electrically coupled to the two electrodes 121
and 122, adapted for eliminating the need for input impedance
matching and thus making the amplifier particularly suitable for
use in measurement and test equipment, and an anti-aliasing filter
(AAF) electrically couple to the instrumentation amplifier and used
before a signal sampler to restrict the bandwidth of a signal to
approximately or completely satisfy the Nyquist-Shannon sampling
theorem over the band of interest.
[0106] Still referring to FIG. 2A, the SoC 124 of the torso sensor
system 110 includes, but is not limited to, a microprocessor unit,
e.g., CPU, a near-field communication (NFC) interface, e.g., NFC
ISO 15693 interface, general-purpose input/output (GPIO) ports, one
or more temperature sensors (Temp. sensor), and analog-to-digital
converters (ADCs) in communication with each other, for receiving
data from the sensor member 123 and processing the received
data.
[0107] Also referring to FIG. 2A, the transceiver 125 of the torso
sensor system 110 is coupled to the SoC 124 for wireless data
transmission and wireless power harvesting. In the exemplary
embodiment, the transceiver 125 comprises a magnetic loop antenna
tuned to compliance with the NFC protocol and configured to allow
simultaneous wireless data transmission and wireless power
harvesting through a single link.
[0108] As shown in FIG. 2A, the sensor member (circuit) 163 of the
extremity sensor system 150 includes a PPG sensor located within a
sensor footprint, which has an optical source having an infrared
(IR) light emitting diode (LED) 161 and a red LED 162, and an
optical detector (PD) electrically coupled to the IR LED 161 and
the red LED 162. The sensor member 163 also includes, but is not
limited to, an LED driver electrically coupled to the two
electrodes 161 and 162 for driving the IR LED 161 and the red LED
162, and a trans Z amplifier electrically coupled to the PD.
[0109] Similarly, as shown in FIG. 2A, the SoC 164 of the extremity
sensor system 150 includes, but is not limited to, a microprocessor
unit, e.g., CPU, a near-field communication (NFC) interface, e.g.,
NFC ISO 15693 interface, general-purpose input/output (GPIO) ports,
one or more temperature sensors (Temp. sensor), and
analog-to-digital converters (ADCs) in communication with each
other, for receiving data from the sensor member (circuit) 163 and
processing the received data. The transceiver 165 of the extremity
sensor system 150 is coupled to the SoC 164 for wireless data
transmission and wireless power harvesting. In the exemplary
embodiment, the transceiver 165 comprises a magnetic loop antenna
tuned to compliance with the NFC protocol and configured to allow
simultaneous wireless data transmission and wireless power
harvesting through a single link.
[0110] In addition, each of the plurality of spatially separated
sensor systems further comprises a plurality of flexible and
stretchable interconnects (FIGS. 2C-2D) electrically connecting to
a plurality of electronic components including the sensor member,
the SoC and the transceiver; and an elastomeric encapsulation layer
(FIGS. 2C-2D) surrounding the electronic components and the
plurality of flexible and stretchable interconnects to form a
tissue-facing surface and an environment-facing surface, wherein
the tissue-facing surface is configured to conform to a skin
surface of the mammal subject. In one embodiment, the encapsulation
layer comprises a flame retardant material.
[0111] In operation, the torso sensor system 110 and the extremity
sensor system 150 are in wireless communication with a reader
system 190, alternatively, the MCU, having an antenna 195, where
one exemplary integrated circuit (IC) of the NFC reader system 190
is shown in FIG. 2H. Specifically, the RF loop antennas 125 and 165
in both the torso sensor system 110 and the extremity sensor system
150 are in wireless communication with the antenna 195 and serve
dual purposes in power transfer and in data communication, as shown
in FIG. 2A. In one embodiment, the reader system 190 also includes,
but is not limited to, an NFC ISO 15693 reader, a circular buffer
and a Bluetooth Low Energy (BLE) interface, which are configured
such that data can be continuously streamed at rates of up to 800
bytes/s with dual channels, which is orders of magnitude higher
than those previously achieved in NFC sensors. A key to realizing
such high rates is in minimizing the overhead associated with
transfer by packaging data into 6 blocks (24 Bytes) in the circular
buffer. The antenna 195 connects to the host system for
simultaneous transfer of RF power to the torso sensor system 110
and the extremity sensor system 150. As such, the sensor network
can operate at vertical distances through biological tissues,
bedding, blankets, padded mattresses, wires, sensors and other
materials found in NICU incubators, for full coverage wireless
operation in a typical incubator. BLE radio transmission then
allows transfer of data to a personal computer, tablet computer or
smartphone with a range of up to 20 m. Connections to central
monitoring systems in the hospital can then be established in a
straightforward manner.
[0112] In another embodiment as shown in FIGS. 2B-2D, the first
sensor system 210 and the second sensor system 250 are similar to
the first sensor system 110 and the second sensor system 150 shown
in FIG. 1A, except that each of the first sensor system 210 and the
second sensor system 250 further comprises a battery 205 for
provide power to said sensor system, and a power management unit/IC
(PMIC) 206 electrically coupled with the battery 205, the Bluetooth
SoC 224/264 and the transceiver (antenna) 195. The power management
unit 206 operably involves dual power operation mode from primary
wireless power transfer and the secondary battery 205 for
portability. In addition, the sensor member (or sensor circuit) 223
of the first sensor system 210 also includes optional electrode for
fECG measurement and 6 axial inertial measurement unit (IMU) for
seismocardiography (SCG) and respiratory rate measurement on the
top of an ECG analog front end (AFE). The sensor member (or sensor
circuit) 263 of the second sensor system 250 also includes also a
PPG AFE and 6 axial IMU for motion artifact reduction algorithm.
The BLE SoC 224/264 of each of the first sensor system 210 and the
second sensor system 250 further comprises a down-sampler and BLE
radio. Each of the power management unit 206 and the sensor members
223 and 263 is controlled by BLE SoC 224/264. In one embodiment,
the accelerometer or the IMU is used to measure at least one of
seismocardiography (SCG) and a respiratory rate. In one embodiment,
the accelerometer or the IMU is used with a motion artifact module
to identify a vital sign as subject to motion artifact and to
correct of motion artifact.
[0113] In certain embodiments, the battery 205 is a rechargeable
battery operably recharged with wireless recharging. In one
embodiment, the electronic components of each of the first sensor
system 210 and the second sensor system 250 further comprises a
failure prevention element that is a short-circuit protection
component or a battery circuit (not shown) to avoid battery
explosion. In one embodiment, the elastomeric encapsulation layer
is configured to electrically isolate the battery from the mammal
subject during use.
[0114] Additionally, the first sensor system 210 is stretchable and
foldable, as illustrated in the top panels of FIG. 2C. The
electrical components and layout are illustrated in the bottom
panel of FIG. 2C, including the components providing a networked
and wireless platform (including a power unit, a memory unit, a
temperature unit, an ECG unit, and a BLE SoC).
[0115] The second sensor system 250, as shown in FIG. 2D, is
configured to attach on an extremity, such as a foot, leg, hand,
arm finger, toe or nail, such as by a wrapping-type mechanism to
secure the main circuit components with a mechanically decoupled
sensor system connected thereto. The second sensor system 250 is
also stretchable and foldable, as illustrated in the top panels of
FIG. 2D. The electrical components including a power unit, a memory
unit, a temperature unit, an ECG unit, and a BLE SoC and layout are
illustrated in the bottom panel of FIG. 2D, including the
components to provide a networked and wireless platform. The sensor
portion may be aligned in a different direction, such as an
orthogonal direction relative to the main circuit components. As
such, the main circuit components may wrap around the foot, with
the sensor portion independently mountable, such as to a nail
region. In one embodiment, the main circuit component can be
wrapped around an extremity without any adhesive, such as around an
ankle. The active sensor portion can independently be attached to a
desired location, such as a foot or a toenail. In this manner, only
a small footprint of the total device needs to be reliably affixed
to the patient, and can even be affixed with an adhesive to a
surface that can more readily withstand the adhesive and
corresponding removal, such as a nail.
[0116] FIG. 2E shows schematically another spatial arrangement of
the main circuit component 264 and the sensor circuit 263 having an
LED units 161 and 162 of the PPG EES 250 (or 150) according to one
embodiment of the invention. The main circuit component 264 and the
sensor circuit 263 including the LED units 161 and 162 are
connected by the serpentine, flexible and stretchable interconnects
170. The main circuit component 264 including at least the SoC and
the transceiver is aligned and operably wrapped around a limb or
appendage in a wrap direction 201. The LED units 161 and 162 extend
at a different direction 202 from the wrap direction 201. As such,
the main circuit component 264 can be wrapped around an extremity
without any adhesive, such as around an ankle. The active sensor
portion can independently be mounted at a desired location, such as
a foot or a toenail. Accordingly, only a small footprint of the
total device needs to be reliably affixed to the patient, and can
even be affixed with an adhesive to a surface that can more readily
withstand the adhesive and corresponding removal, such as a nail.
In one embodiment, the sensor member of the PPG EES 250 (or 150) is
conformable to a skin surface and configured as a soft wrap for
circumferential attaching to the limb or appendage region.
[0117] In yet another embodiment as shown in FIGS. 2F-2G, the first
sensor system 310 and the second sensor system 350 are similar to
the first sensor system 110 and the second sensor system 150 shown
in FIG. 1A, except that each sensor member 323/363 of the first
sensor system 310 and the second sensor system 350 further
comprises a clinical grade temperature sensor. In addition, the
sensor member 323 of the first sensor system 310 also includes
3-axis accelerometer. Furthermore, each of the first sensor system
310 and the second sensor system 350 includes, instead of an NFC
SoC 124/164 shown in FIG. 1A, a BLE SoC 324/264.
[0118] FIG. 3 is an illustration of torso and extremity sensor
systems (chest unit and foot unit) of a sensor network that support
continuous 24/7 use without external wires and, at most, a gentle
adhesive such as a hydrogel, according to one embodiment of the
invention. In this exemplary embodiment, the torso sensor system
(i.e., Chest Unit) has an L.times.W.times.H dimension of 4.4
cm.times.2.4 cm.times.0.5 cm, and adapted to measure ECG, heart
rate, temperature (medical grade), RR, motion detect. the extremity
sensor system (i.e., Foot Unit) has an L.times.W.times.H dimension
of 4.5 cm.times.2.7 cm.times.0.5 cm, and adapted to measure
SpO.sub.2 (from PPG at 100 Hz), and temperature (medical
grade).
[0119] FIG. 4 shows one embodiment of a PPG sensor system
configured to conformally wrap around an appendage (to panel), with
the sensor wrapped around a doll and a neonate foot in the
respective bottom panels.
[0120] Referring back to FIG. 1A, the MCU 190 is configured to
receive, from the sensor systems 110 and 150, output signals
representing the physiological parameters, and to display the
physiological parameters of the mammal subject.
[0121] Specifically, in certain embodiments, the MCU 190 is
configured to perform at least one function of receiving and
processing measured data of the physiological parameters from the
plurality of spatially separated sensor systems; transmitting the
processed data of the physiological parameters to at least one of a
patient database, a cloud server, and a mobile device; continuously
multi-modal monitoring one or more critical parameters associating
at least one vital sign; and notifying a practitioner or caregiver
when a sensor aberrant signal output condition occurs; and
generating an alarm when an alarming vital sign reading condition
in which the one or more of the critical parameters are out of
pre-defined ranges occurs, and notifying a practitioner or
caregiver of the alarm. In one embodiment, the one or more critical
parameters are one or more of the heart parameters, brain
activities, temperature, body movements, respiratory parameters,
oxygenation, vocalization parameters, swallow parameters, and blood
pressure and blood flow.
[0122] In certain embodiments, the MCU 190 is configured to further
perform at least one function of assessing body pain of the mammal
subject, based on the physiological parameters including a heart
rate, heart rate variability, respiratory rate, respiratory effort,
and crying time, and notifying a practitioner or caregiver where
the pain is assessed; assessing local blood perfusion of the mammal
subject, based on a location specific pulse oximetry derived from
peripheral oxygen saturation (SpO.sub.2) measured by pulse
oximeters of the sensor systems placed on various locations of the
body; detecting an apneic event when sudden decreases or cessation
of the respiratory rate followed by compensatory increases in the
heart rate and decreases in the SpO.sub.2; and notifying a
practitioner or caregiver when the apneic event occurs, and
vibrating the sensor systems itself to trigger the mammal subject
to change its position or awake from sleep; and localizing
anatomical pathology based on the physiological parameters measured
by the plurality of spatially separated sensor systems placed in
differential locations. In one embodiment, the MCU, for instance,
can be used to localize lung pathology for the diagnosis of
lobe-specific pneumonia or infection.
[0123] In one embodiment, the MCU comprises a mobile device for at
least one of real-time display of the physiological parameters,
recording of the physiological parameters, and alarm.
[0124] In one embodiment, the mobile device in bi-directionally
wireless communication with the plurality of spatially separated
sensor systems. In one embodiment, the mobile device is in wireless
communication with the patient database. In one embodiment, the
mobile device is a hand-held device or a portable device having a
graphical user interface to display the plurality of physiological
parameters.
[0125] In one embodiment, the sensor network further comprises a
power unit for wirelessly powering the sensor systems. In one
embodiment, the sensor network is capable of operating wirelessly
for a period of at least 24 hours without a source of external
power.
[0126] In one embodiment, at least one of the plurality of
spatially separated sensor systems further comprises an actuator
configured to generate a force for providing a stimulus to the
mammal subject when a pre-defined trigger signal is detected. In
one embodiment, the stimulus comprises gentle vibrations for
soothing the mammal subject. In one embodiment, the actuator is one
or more of an electromechanical motor, a heater, and an electrical
stimulator.
[0127] FIG. 5 shows a flowchart of a method for measuring
physiological parameters of a mammal subject, according to certain
embodiments of the invention. In certain embodiments, the method as
shown in FIG. 5 may be implemented on the sensor network shown in
FIG. 1A. It should be particularly noted that, unless otherwise
stated in the disclosure, the steps of the method may be arranged
in a different sequential order, and are thus not limited to the
sequential order as shown in FIG. 5.
[0128] As shown in FIG. 5, at procedure 510, a sensor network
including a plurality of sensor systems (i.e., the first sensor
system 110 and the second sensor system 150 as shown in FIG. 1A1B)
are deployed in the mammal subject. Said deploying procedure 510
includes respectively attaching at least one first sensor system to
a central region of the mammal subject and at least one second
sensor system to an extremity region of the mammal subject such
that the first sensor system and the second sensor system are
spatially separated by a distance. For example, the first sensor
system 110 is attached to a first position in the torso region 410
of the mammal subject for measuring a heartbeat of the mammal
subject, and the second sensor system 150 is attached to a second
position in the limb region 420 of the mammal subject for measuring
a pulse of the mammal subject. Further, the sensor systems 110 and
150 are in wireless communication with the MCU 190, and spatially
separated by a distance defined by the first and second positions.
As deployed, the sensor network is corresponding to a bidirectional
wireless communication system. As used in the disclosure, the term
"bidirectional wireless communication system" refers to onboard
components of the sensor that provides capability of receiving and
sending signals. In this manner, an output may be provided to an
external device, including a cloud-based device, personal portable
device, or a caregiver's computer system. Similarly, a command may
be sent to the sensors, such as by an external controller, which
may or may not correspond to the external device. Machine learning
algorithms may be employed to improve signal analysis and, in turn,
command signals sent to the medical sensor, including a stimulator
of the medical sensor for providing haptic signal to a user of the
medical device useful in a therapy. More generally, these systems
may be incorporated into a processor, such as a microprocessor
located on-board or physically remote from the electronic device of
the medical sensor.
[0129] At procedure 520, the plurality of spatially separated
sensor systems is time-synchronized to a common time base. As used
in the disclosure, the term "time-synchronized" or "time synced"
refers to measurement of a parameter by different sensors,
including at different locations, which are synchronized in time to
allow for measurement of novel physiological parameters. Examples
include master-slave linked sensor systems that allows for time
synced measurements. For example, certain embodiments of the
invention utilize a multiprotocol functionality that incorporates a
secondary 2.4 Ghz radio protocol other than Bluetooth to create a
private star network among the network of sensors. The secondary
radio protocol allows one of the sensors to act as the central hub
to broadcast the local clock based on its crystal oscillator to
create a common clock within the sensor network. Every sensor can
have a local clock running and will adjust the local clock value
based on the broadcasted clock value. The central hub can
additionally communicate with the base station (including, for
example, a remote reader or a receiver) to synchronize its local
clock to the base station's clock. The private star network is not
bounded to the base station allowing two different body-sensor
networks to be synchronized in time without the need for a central
hub. This is relevant in situations where the sensors function as
blind data collection tools with data that can be downloaded and
used later via a base unit.
[0130] The common clock can timestamp all of the signals captured
through the sensors that the private star network uses allowing
novel algorithms that depend on a common clock to be used in the
sensor system. The only source of time lag/drift is from the
crystal oscillator that is typically low (0.0004%). This time lag
can be adjusted and corrected via the central hub at a frequency
determined by the user.
[0131] At procedure 530, data of the physiological parameters are
measured from the plurality of spatially separated sensor
systems;
[0132] At procedure 540, the time synchronized measured
physiological parameters are wirelessly transmitted to at least one
of a patient database, a cloud server, and a mobile device. In one
embodiment, said wirelessly transmitting procedure 540 includes
receiving and processing the measured data of the physiological
parameters from the plurality of spatially separated sensor
systems; and transmitting the processed data of the physiological
parameters to at least one of a patient database, a cloud server,
and a mobile device.
[0133] In one embodiment, said wirelessly transmitting procedure
540 is performed with the MCU in wireless communication with the
plurality of spatially separated sensor systems.
[0134] In one embodiment, the method further comprises associating
the wirelessly transmitted physiological parameters with a unique
patient identifier, thereby identifying the physiological
parameters with the mammal subject in at least one of the patient
database, the cloud server, and the mobile device.
[0135] In one embodiment, the method further comprises identifying
a normal vital sign reading condition, an aberrant sensor output
condition, or an alarming vital sign reading condition, based on
the physiological parameters. In one embodiment, the aberrant
sensor output condition is one or more of a lead off state where
the tissue-facing surface of a sensor system is not in intimate
contact with an underlying patient surface; a patient motion
artifact; or an output discrepancy relative to at least two
different sensor systems. In one embodiment, the aberrant sensor
output condition is identified when at least one vital sign
detected from the first sensor system differs from that detected
from the second sensor by 25% or greater.
[0136] In one embodiment, the method further comprises continuously
multi-modal monitoring one or more critical parameters associating
with the at least one vital sign; and notifying a practitioner or
caregiver when the sensor aberrant signal output condition
occurs.
[0137] In one embodiment, the method further comprises generating
an alarm when the alarming vital sign reading condition in which
the one or more of the critical parameters are out of pre-defined
ranges occurs, and notifying a practitioner or caregiver of the
alarm.
[0138] In one embodiment, the one or more critical parameters are
one or more of the heart parameters, brain activities, temperature,
body movements, respiratory parameters, oxygenation, vocalization
parameters, swallow parameters, and blood pressure and blood
flow.
[0139] In one embodiment, the method further comprises at least one
of assessing body pain of the mammal subject, based on the
physiological parameters including a heart rate, heart rate
variability, respiratory rate, respiratory effort, and crying time,
and notifying a practitioner or caregiver where the pain is
assessed; assessing local blood perfusion of the mammal subject,
based on a location specific pulse oximetry derived from the
SpO.sub.2 measured by pulse oximeters of the sensor systems placed
on various locations of the body; detecting an apneic event when
sudden decreases or cessation of the respiratory rate followed by
compensatory increases in the heart rate and decreases in the
SpO.sub.2, and notifying a practitioner or caregiver when the
apneic event occurs, and vibrating the sensor systems itself to
trigger the mammal subject to change its position or awake from
sleep; and localizing anatomical pathology based on the
physiological parameters measured by the plurality of spatially
separated sensor systems placed in differential locations.
[0140] In one embodiment, the method further comprises displaying
at least one of the physiological parameters, notifications, and
the alarm in a display having a graphical user interface.
[0141] In one embodiment, the method further comprises securing the
display of the physiological parameters by requiring a secure login
before a user can access the physiological parameters.
[0142] In one embodiment, the user is a practitioner or caregiver,
the mammal subject or family member, and the method further
comprises wirelessly communicating between the practitioner or
caregiver and the mammal subject or family member based on the
physiological parameters.
[0143] In one embodiment, the method further comprises securely
sending a command from a remote practitioner or caregiver to a
practitioner or caregiver in proximity to the mammal subject based
on the physiological parameters.
[0144] In one embodiment, the method further comprises actuating an
actuator to generate a force for providing a stimulus to the mammal
subject when a pre-defined trigger signal is detected. In one
embodiment, the stimulus comprises gentle vibrations for soothing
the mammal subject.
[0145] It should be noted that all or a part of the methods
according to the embodiments of the invention is implemented by
hardware or a program instructing relevant hardware.
[0146] Yet another aspect of the invention provides a
non-transitory computer readable storage medium/memory which stores
computer executable instructions or program codes. The computer
executable instructions or program codes enable a computer or a
similar computing apparatus to complete various operations in the
above disclosed method of non-invasively measuring physiological
parameters of a mammal subject. The storage medium/memory may
include, but is not limited to, high-speed random access
medium/memory such as DRAM, SRAM, DDR RAM or other random access
solid state memory devices, and non-volatile memory such as one or
more magnetic disk storage devices, optical disk storage devices,
flash memory devices, or other non-volatile solid state storage
devices.
[0147] According to the invention, the sensor network has
applications including, but not limited to, critical care
monitoring in neonatal intensive care units; critical care
monitoring in pediatric intensive care units; critical care
monitoring in neonatal/pediatric cardiac care units; critical care
monitoring in neonatal/pediatric neurocritical care units; home
monitoring for high-risk neonates.
[0148] The sensor networks according to embodiments of the
invention have a number of advantages. For example, the sensor
systems are fully integrated and capable of recapitulating full
vital signs monitoring necessary for critical care. The at least
two sensor systems include, but is not limited to, ECG,
high-frequency accelerometer, gyroscope, temperature sensor,
photoplethysmography unit, EMG. These sensors enable the widest
measurement to date for a wearable sensor system that include
traditional vital signs and novel physiological metrics that extend
beyond current standard of care.
[0149] Sensing capabilities include, but are not limited to, vital
signs: heart rate, respiratory rate, skin temperature (central and
peripheral), core temperature sensor (when placed underneath the
axilla), blood oxygenation.
[0150] Novel physiological metrics include, but are not limited to,
cuff-less blood pressure (via pulse arrival time or pulse transit
time), crying time, swallow count, chest wall displacement, heart
sounds, core body position, skin temperature differentials between
a central location (e.g. trunk) and distal location (e.g.
limb).
[0151] The sensor network according to embodiments of the invention
can be used to correlate chest wall movement overlying the heart
with stroke volume and ejection fraction measured by
echocardiography.
[0152] The sensor network according to embodiments of the invention
allows analysis of a baby's position including when a baby is
upright. This can be used to quantify important parameters such as
how long a baby is being held for kangaroo care.
[0153] According to embodiments of the invention, the output of the
sensor systems can be used to assess a variety of metrics,
including to determine whether a baby has sustained an injury that
is consistent with non-accidental trauma (e.g. child abuse), and
can measure vocalization, crying time as a metric of discomfort or
pain, asynchronous motion of the limbs, and/or sleep quality
assessments with core body position measurement (laying face down,
on the side, on the back); neonates sleep safest flat on their
back, with other positions at a greater risk for sudden infant
death syndrome (SIDS).
[0154] According to embodiments of the invention, unique mechanical
layouts enable safe deployment on the fragile skin of mobile
infants. Layered design of the circuitry allows for mechanical
isolation of higher modulus components in a mechanical island;
bending/twisting/stretching does not disturb the underyling sensor
or other stain-sensitive components. The pulse oximeter unit is
configured as a soft wrap that allows for circumferential
affixation to the foot or hand of a neonate. This configuration
reduces motion artifact and allows for maximal signal fidelity for
SpO.sub.2. The soft, mechanical nature of the sensor itself enables
intimate skin coupling without the need of powerful adhesives
reducing the risk for iatrogenic skin injuries. Embodiments where
the form factor occupies a small surface area (less than 2.0
cm.times.4.0 cm) facilitates placement on a premature neonate.
[0155] According to embodiments of the invention, unique isolation
of electrical components enable operation in critical care
settings. Battery is current isolated allowing for enhanced
electrical safety to the neonate. Electrodes are able to be
adjusted in spacing--allowing for accommodation of subjects of
drastically different chest wall sizes (e.g. premature infant at 25
weeks gestational age vs adult subject). The electrical components
are shielded enabling operation even during life-saving medical
interventions such as cardiac defibrillation. Low power operation
enabling 24 hours of continuous use between charges. Battery has
failure preventions including short circuit protection and battery
explosion circuitry. Flame retardation of the elastomer
encapsulation reduces risk of injury.
[0156] According to embodiments of the invention, the wearable
sensors fully support Bluetooth 5 technology enabling drastically
extended sensing ranges with a base unit. Master-slave linked
sensor system allows for time synced measurements of novel
physiological parameters. Of course, the network systems provided
herein are compatible with any number of communication protocols,
including ultra wide band and narrow band communication
protocols.
[0157] According to embodiments of the invention, the sensor
systems provide transparent windows allowing for direct visual
inspection of the skin underneath without removing the system.
Perforated holes enable wicking away of sweat. Adhesives that have
variable peel force based on the directionality of removal.
Adhesives are placed strategically around the edges of the device
(and not the center) to reduce total skin adhesive area as a method
of reducing the risk of iatrogenic injury. Methods where a
long-lasting adhesive (>24 hours adherence) is placed on the
neonate with an additional mechanical communication. Peel force on
sensitive, fragile skin can be reduced by use of a hydrogel. This
is particularly relevant for neonate skin.
[0158] According to embodiments of the invention, respiratory rate
algorithms are derived from chest wall movement that more
accurately reflects true physiological function. Algorithms to
derive SpO.sub.2 with improved sensing accuracy in spite of motion
artifact. Dual heart rate sensing coupled from both the ECG and
high frequency accelerometer. Dual measurement systems to capture
accurate respiratory rate. The measurement of respiratory rate
derived through the ECG via impedance pneumonography is often times
inaccurate and overestimates the true respiratory rate. Described
herein is the ability to measure chest wall movement to derive
respiratory rate along with traditional impedance pneumonography.
Continuous cross-validation is possible. High frequency
accelerometer enables electrode-free method that avoids the need
for additional skin preparation for the measurement of heart rate
and respiratory rate; signal processing enables distinction between
chest wall movement associated with breathing compared to heart
rate.
[0159] According to embodiments of the invention, the sensor
network has advanced software function and interoperability
enabling cloud storage, remote login, and secure communication.
Further capabilities include the integration of third-party
sensors, wearables, and other hardware systems as well as paired
integration with electronic health records.
[0160] Medical applications of the sensor network include, but are
not limited to, multimodal sensing, including pulseless electrical
activity. The ECG on the chest can pick up perfect ECG, heart,
etc., but the heart is not actually pumping blood (in instances of
hypovolemic shock). The accelerometer or the PPG can corroborate or
refute the presence of cardiac activity. Another aspect is
assessing pediatric/neonatal pain: given that neonates are
non-verbal, measurement and assessment of pain is difficult.
Accordingly, the sensor network can provide various measures
relevant to pain including, but not limited to heart rate, heart
rate variability, respiratory rate, respiratory effort, crying
time. This further enables the ability to notify a provider or
practitioner where pain is assessed. Kangaroo mother care (KMC):
For instance, during skin-to-skin or "kangaroo care" where a baby
is placed on the mom's chest, the ECG sensors can be placed on the
back or flank of the neonate. Algorithms enable the detection of
baby position in space and classification of positions relevant to
kangaroo care.
[0161] In certain embodiments, the pulse oximeter unit is placed on
various locations of the body to derive a measure location specific
pulse oximetry. Locations include but are not limited to: all four
limbs, chest, back, abdomen, forehead. These locations enable
assessment of local blood perfusion--for instance, in the context
of the forehead, the SpO.sub.2 can be used as a reflection of
cerebral perfusion. Detection of apneic events: sudden decreases or
cessation of respiratory rate followed by compensatory increases in
heart rate and decreases in SpO.sub.2 may suggest the need
intervention; this intervention include notification of a
healthcare provider or vibration of the sensor itself to trigger
the neonate to change position or awake from sleep. Beyond critical
care, these devices may be used in the post-surgical setting, the
home setting, or in adult care settings.
[0162] In certain embodiments, the form factor includes a single
chest unit sensor with all electronics and vital sign monitoring
functionality.
[0163] In certain embodiments, the sensor network has the ability
to create alarms based on pre-programmed or physician specified
inputs. These alarms include both visual and audio notifications.
These notifications can be displayed on an external display unit or
onboard the sensor itself (either via an onboard LED or sound).
[0164] In certain embodiments, the optical unit of the
photoplethysmograph is located on the infant's nail (toenail or
fingernail). Adherence to the nail allows for an excellent
device/skin interface. The nail is surface with negligible risk of
injury and no risk of irritation.
[0165] In certain embodiments, an electromechanical motor is
integrated within the sensor unit--gentle vibration is soothing for
babies and often times induces sleep. The sensors can act as
sensing-therapeutic couplers. The sensing of crying can trigger a
gentle vibration that soothes the baby.
[0166] Certain aspects of the invention disclose a sensor network
for wireless monitoring of physiological parameters comprising a
plurality of time-synchronized sensor systems, wherein each sensor
system comprises a sensor to monitor a physiological parameter; a
bidirectional wireless communication system for wirelessly
transmitting data to and from the plurality of time-synchronized
sensor systems; and a remote reader in communication with the
bidirectional wireless communication system for real-time display
of the monitored physiological parameters, recording of the
monitored physiological parameters, and/or alarm for an out of
agreement state.
[0167] In certain embodiments, a first sensor system is configured
to attach to a central patient region and a second sensor system is
configured to attach to an extremity patient region.
[0168] In certain embodiments, the central patient region comprises
a chest region, a neck region including the suprasternal notch
area, or a head region including a forehead region or anterior
fontanelle region of a neonate.
[0169] In certain embodiments, the extremity patient region
comprises one or more of: a limb region, a foot region, a hand
region, a toenail region or a fingernail region.
[0170] In certain embodiments, a sensor output triggers an
indicator to indicate a vital sign is of lower confidence.
[0171] In certain embodiments, the sensor output alters an
executable algorithm in a microprocessor of the sensor system.
[0172] In certain embodiments, the altered executable algorithm
comprises one or more of a filter, a display parameter or a
correction factor.
[0173] In certain embodiments, the sensor network further comprises
a microprocessor for receiving the physiological parameter data
from the plurality sensors; and an alarm module executable on the
microprocessor to determine if at least two sensors are in an out
of agreement condition.
[0174] In certain embodiments, the sensors monitor a plurality of
physiological parameters to provide multi-modal monitoring of a
critical parameter to reduce false positives and notify a caregiver
of a sensor aberrant signal capture condition.
[0175] In certain embodiments, the sensor network further comprises
at least three independent sensors that monitor the same
physiological parameter, wherein the sensors measure a different
physical parameter, and the different physical parameters each
provide an independent measure of a critical vital sign, and are
optionally located at different locations on a patient body.
[0176] In certain embodiments, the sensor network further comprises
a processer that executes an agreement calculator module to send a
signal to an alarm to notify a clinician of an out of range vital
sign for a condition corresponding to at least three independent
sensors in agreement of the out of range vital sign; or send an
aberrant sensor signal condition for an out of range vital sign
measured by only one of the at least three sensors; thereby
increasing sensor network sensitivity, positive predictive value
and reducing false negatives.
[0177] In certain embodiments, the sensor network further comprises
an accelerometer sensor for use with a motion artifact module to
identify a vital sign as subject to motion artifact and/or to
correct of motion artifact.
[0178] In certain embodiments, the critical parameter is one or
more of heart rate, brain activity, temperature, patient motion,
respiration or blood-flow.
[0179] In certain embodiments, the sensors are one or more of, an
ECG sensor, and EKG sensor, a pulse oximeter sensor, a temperature
sensor, a blood pressure sensor, an accelerometer, or an acoustic
sensor; and a microprocessor constantly compares values from each
of the sensors and an alarm module generates a signal for the out
of agreement condition between the at least two sensors.
[0180] In certain embodiments, the sensor network further comprises
an actuator in wireless communication with the remote reader
configured to receive an actuation signal to actuate underlying
tissue.
[0181] In certain embodiments, the actuator is one or more of an
electromechanical motor, a heater, and an electrical
stimulator.
[0182] In certain embodiments, the reader provides continuous
display of a critical parameter even under a sensor-fail
condition.
[0183] In certain embodiments, the sensor network further comprises
a wireless power unit for wirelessly powering the sensors.
[0184] In certain embodiments, the sensors operate continuously,
including over a time period that is greater than 8 hours, or
between about 8 hours and 1 day, without recharging.
[0185] In certain embodiments, the sensors measure one or more
physiological parameters that are crying time, crying frequency,
swallow count, swallow frequency, chest wall displacement, heart
sounds, core body position, skin temperature differentials,
asynchronous limb motion, speaking.
[0186] In certain embodiments, the sensor network is configured for
use with a pediatric or neonate patient.
[0187] In certain embodiments, the monitored vital signs provide an
indication of pain magnitude.
[0188] In certain embodiments, the sensor network further comprises
an actuator to generate a force configured to provide a stimulus to
a patient.
[0189] In certain embodiments, the patient is a neonate or a
pediatric patient, and the actuator comprises an electromechanical
motor configured to provide a soothing vibratory force to the
patient.
[0190] In certain embodiments, the sensor detects crying and
provides a signal to automatically actuate the actuator and sooth
the patient.
[0191] In certain embodiments, the sensor network further comprises
a remote controller configured to have two-way wireless
communication with the sensors.
[0192] In certain embodiments, the remote controller is operably
connected to a patient database.
[0193] In certain embodiments, the remote controller is a hand-held
device or a portable device having a graphical user interface to
display the plurality of monitored physiological parameters.
[0194] In certain embodiments, the remote controller and the
receiver are integrated as a single unit.
[0195] In certain embodiments, the sensor network is capable of
operating wirelessly for a period of at least 24 hours without a
source of external power.
[0196] In certain embodiments, the time synchronized sensors
synchronizes the physiological parameter data from the plurality
sensors independent of sensor position, including for multiple
spatially separated sensors used to determine a common
physiological parameter.
[0197] In certain embodiments, each of the plurality of sensor
systems comprise: a plurality of electronic components; a
serpentine interconnect that electrically interconnects different
electronic components; an elastomeric encapsulation layer that
surrounds the plurality of electronic components and serpentine
interconnect to form a bottom tissue-facing surface and a top
environment-facing surface; an antenna for wirelessly communicating
a physiological parameter measured from the sensor system; wherein
the bottom tissue-facing surface is configured to conform to a skin
surface.
[0198] Certain aspects of the invention also disclose a method of
monitoring one or more vital signs of a neonate or a pediatric
patient, the method comprising the steps of: providing the sensor
network disclosed above; conformally contacting the first sensor
with a first region of the patient; conformally contacting the
second sensor with a second region of the patient that is spatially
separated from the first region; detecting with the first and
second sensors one or more physiological parameters that are
related to a vital sign; and wirelessly transmitting the detected
physiological parameters or the vital sign to a remote controller
unit; thereby monitoring one or more vital signs.
[0199] In certain embodiments, the vital sign is one or more of:
heart parameter (rate, intensity, variability), respiratory
parameter (rate, intensity, variability), temperature, oxygenation
(level, variability, minimum, maximum), vocalization parameter
(crying duration, frequency, intensity), swallow parameter, and
blood pressure.
[0200] In certain embodiments, the method further comprises the
step of associating the wirelessly transmitted the physiological
parameters with a unique patient identifier; thereby identifying
the physiological parameters with a patient.
[0201] In certain embodiments, the method further comprises the
step displaying the transmitted physiological parameters in a
display having a graphical user interface.
[0202] In certain embodiments, the method further comprises the
step of securing the display of transmitted physiological
parameters by requiring a secure login step before a user can
access the transmitted physiological parameters.
[0203] In certain embodiments, the user is a healthcare
professional and a patient or family member, further comprising the
step of wirelessly communicating between the healthcare
professional and the patient or family member based on the detected
physiological parameters or the vital sign.
[0204] In certain embodiments, the method further comprises the
step of the user that is a remote healthcare professional securely
sending a command to a proximate healthcare professional in
proximity to the patient based on the transmitted physiological
parameters.
[0205] In certain embodiments, the method further comprises the
steps of determining a vital sign from at least two different
sensors within two different sensor systems; comparing the at least
two vital sign determinations; identifying from the comparing step
one of a normal vital sign reading condition; an aberrant sensor
output condition; or an alarming vital sign reading condition.
[0206] In certain embodiments, the aberrant sensor output condition
is one or more of a lead off state, wherein a bottom surface of a
sensor system is not in intimate contact with an underlying patient
surface; a patient motion artifact; or an output discrepancy
relative to at least two other sensors.
[0207] In certain embodiments, the aberrant sensor output condition
is identified for at least one vital sign from a first sensor that
differs from another vital sign from a second sensor that is at
least 25% different.
[0208] In certain embodiments, the method further comprises the
step of identifying the sensor having the aberrant sensor output
condition and alerting a caregiver of the condition to take action
to correct the sensor output.
[0209] In certain embodiments, for an alarming vital sign reading
condition, the method further comprises generating an alarm signal
to alert a health care professional.
[0210] In certain embodiments, the vital sign is one or more of
temperature, heart rate, respiratory rate or movement.
[0211] In certain embodiments, the physiological parameter is
position, and the vital sign corresponds to a baby position that is
a laying position.
[0212] In certain embodiments, the wireless transmitting is by a
Bluetooth protocol.
[0213] In certain embodiments, the vital sign is respiratory rate
derived from a sensor that measures chest wall movement.
[0214] In certain embodiments, the vital sign is SpO.sub.2, the
method further comprising the step of improving SpO.sub.2 accuracy
by accommodating any motion artifact.
[0215] In certain embodiments, the vital sign is heart rate, and
the method further comprises detecting heart rate from both an ECG
sensor and a high frequency accelerometer, thereby providing
continuous cross-validation.
[0216] In certain embodiments, the vital sign is respiratory rate,
and the method further comprises measuring a chest wall movement
with a first sensor and impedance pneumonography with a second
sensor, thereby providing continuous cross-validation.
[0217] In certain embodiments, the method further comprises the
step of storing the transmitted physiological parameters or vital
sign in a network of servers.
[0218] Certain aspects of the invention further disclose a
battery-powered, wireless (e.g., Bluetooth 5 enabled) vital signs
monitoring system that exploits a bi-nodal pair of thin,
low-modulus measurement modules, capable of gently and
non-invasively interfacing onto the skin of neonates, even at
gestational ages that approach the limit of viability. The key
distinguishing features of this technology includes low-battery
power operation enabling at least 24-hour continuous use between
charges while enabling monitoring of a full suite of vital signs.
The designs enable measurement of traditional vital signs in
addition to advanced physiological parameters not currently
measured. The skin interface and electrical/mechanical design of
the sensor allows for safe integration with fragile neonatal skin
even during life-saving interventions such as cardiac
defibrillation.
[0219] Also disclosed herein are methods of monitoring using any of
the sensor networks, sensor systems and electronic components
described herein. Also provided herein are sensor networks for
carrying out any of the methods described herein.
[0220] These and other aspects of the present invention are further
described below. Without intent to limit the scope of the
invention, examples according to the embodiments of the present
invention are given below. Note that titles or subtitles may be
used in the examples for convenience of a reader, which in no way
should limit the scope of the invention. Moreover, certain theories
are proposed and disclosed herein; however, in no way they, whether
they are right or wrong, should limit the scope of the invention so
long as the invention is practiced according to the invention
without regard for any particular theory or scheme of action.
Sensor Network Overview and Electrical Components
[0221] Each of the sensor systems comprises a plurality of
electrical components, as schematically illustrated in FIGS. 2A-2G,
depending on the functionality of each sensor system. Each of FIGS.
2A-2C and 2F shows a schematic of an electrocardiography (ECG)
sensor system according to different embodiment of the invention,
which is configured to measure additional physiological parameters,
such as temperature and position/motion. The electrodes and
accelerometer are connected to complementary electrical components
such as amplifiers and filters. Each of FIGS. 2A, 2B, 2D and 2G
illustrates a photoplethysmography (PPG) sensor system according to
different embodiment of the invention, which includes a temperature
sensor. The PPG sensor includes a photodetector and optical source,
such as an infrared or red light, including a light emitting diode
(LED). Associated electronic components include an amplifiers and
filters. Wireless communication to a microprocessor, including
Bluetooth low energy (BLE) communication.
[0222] Representative geometries are provided in FIG. 4 for
appendage mounting, including, as illustrated, a foot. Details of
two sensor systems are summarized in FIG. 3. The combination of
time-synchronized sensor systems, including such as those of FIG.
3, provides a number of important benefits. For example, multiple
vital signs can be independently monitored and cross-checked
against one another to provide higher-fidelity monitoring and
information to distinguish between serious medical events compared
to sensor malfunction arising, for example, from bad contact with
the skin. The sensor systems have functional characteristics of
being wireless, with a long battery life, and having, at most, a
biologically-gentle adhesive such as a hydrogel, between the sensor
system and the skin. The chest sensor system can measure ECG, heart
rate, temperature (medical grade), respiratory rate (RR) and motion
detection. The foot sensor system can measure oxygen saturation
(SpO.sub.2) and temperature. Together, the systems can measure
blood pressure from pulse arrival time (PAT) or pulse transit time
(PTT).
[0223] FIGS. 2C-2D is a schematic illustration of one sensor
system, with the top panels illustrating the undeformed sensor
system, a stretched sensor system, and a folded or twisted sensor
system. The bottom panel is a schematic illustration of the various
positions of the electrical components and the ability of the
system to accommodate various applied forces, including stretching
(buckling) and folding (bending) by use of thin layered
electronics, serpentine electrical interconnects, and positioning
of stress-sensitive components (e.g., electrodes, integrated
circuits and chips, power source, communication components, and
processers). The system may be encapsulated with an encapsulation
layer, including a continuous encapsulation layer as there is no
need for external wire connections.
[0224] A similar sensor system, but configured for appendage or
limb mounting, is illustrated in FIG. 2E. The upper panels
illustrate the sensor configured to be wrapped around an appendage
or limb.
[0225] The PCB can be fabricated using 3/3 mil trace spacing, down
to 3/2 mil trace spacing depending on the application of interest.
The PCB may comprise a plurality of stacked layers, with a
thickness of about 6.92 mil (e.g., less than about 0.2 mm).
[0226] The sensing capabilities of the sensor network and systems
provided herein provides a range of sensing capabilities, including
measuring parameters related to one or more of heart rate, heart
rate variability, respiratory rate, skin temperature, pulse
oximetry, ballistocardiography, respiratory effort, crying time,
swallowing count, cuff-less blood pressure.
[0227] Charging platform preferably has a receiver dimension less
than 15.times.15 mm.sup.2, a power transfer capacity up to 200 mW,
and an effective wireless charging distance up to about 2 to 3 cm.
The wireless charging is similar to the standard WPC Qi, although
the actual Qi standard tends to be inadequate for the instant
systems. The receiver-side requirement is a coil with resonance
frequency of 110-205 kHz, where a bigger coil for resonant
frequency is provided herein. An additional magnetic flux shield is
necessary for higher efficiency and inductance-coil turn ratio, but
such a shield adds unnecessary bulkiness to the sensor systems,
making it difficult to achieve long-term wearability.
[0228] The NFC and Qi standards are compared, including by
frequency range (13.56 MHz vs. 110-205 kHx), charging power range
(100-500 mW vs. 5-120 W) and typical receiver size (>10.times.10
mm.sup.2 vs. 45.times.45 mm.sup.2).
[0229] An exemplary electronic component is an NFC Reader IC, such
as ST25R3911A NFC Reader IC (FIG. 1G). An NFC initiator/HG reader
can be used for the charger platform. Up to 1.4 W of transmitting
power output with differential driving support is obtained. In this
manner, transmitter control and wake-up mode for power efficiency
is achieved. Small size and weight sensor systems are achieved,
that are conformable to a body surface and light-weight, such as
4.7 cm.times.2.2 cm.times.0.5 cm (4.8 g) or 4.0 cm.times.1.9
cm.times.0.5 cm (4.6 g).
Software and Algorithms
[0230] FIG. 6 illustrates a flowchart of operation of a sensor
network system according to one embodiment of the invention. In the
exemplary embodiment, the operation of the sensor network starts to
check whether the battery module needs to be charged or not. If the
charging is needed, the system synchronizes on-board memory and
perform firmware update and then go back to check if the battery
module needs to be charged. If no charging is needed, the system
initializes peripherals and then enters a low power mode, followed
by checking whether the sensor systems are connected or not. If no,
the sensor network system advertises to request to connect to a
host, and then enters the low power mode. If yes, the sensor
systems sample signals and the sampled signals are then processed
with digital signal process (DSP). The processed signals are
subjected to BLE transfer and meanwhile writes the transfer in an
on-board memory log. Then repeating the signal sampling process.
The systems are compatible with any number of hardware devices and
platforms, including mobile phones, handhelds and computers.
[0231] Referring to FIG. 7, a high-level cloud architecture
schematic is shown according to one embodiment of the invention.
Generally, the sensor network for real-time monitoring, patient
database storing data of real-time monitoring from the sensor
network, and device management are operably in bidirectional
wireless communication with user interface and/or third party
analysis engine, and also operably in wireless communication with
mobile devices, such smartphones and tablets. In addition, the
monitor data may be stored in hospital's electronic health record
system that may be in communication with a Bluetooth enabled
device.
[0232] FIG. 8A shows an algorithm using an ECG sensor for
respiratory rate (RR) estimation according to one embodiment of the
invention. FIG. 8B illustrates the RR estimation using the
algorithm shown in FIG. 8A, based on the ECG signal measured by the
ECG sensor, with a plot of the actual count compared to the ECG EES
provided in FIG. 8C. For example, as shown in FIG. 8B, the peaks p1
(top right panel) is detected from the measured ECG (top left
panel), then the envelope of the peaks p1 is determined (bottom
left panel). The peaks p2 of the determined peak envelope is
detected (bottom right panel) for the RR estimation.
[0233] FIG. 9A shows an algorithm using chest wall movements for
the RR estimation according to another embodiment of the invention.
FIG. 9B illustrates determination of the RR using the algorithm
shown in FIG. 9A, based on the measured chest wall movements, for
example, measured by an accelerometer. In this embodiment, the SCG
signal associated with the chest wall movements (top left panel) is
processed with a bass pass filter (BPF) to obtain a band pass
filtered (f.sub.c1=0.5 Hz, f.sub.c2=5 Hz) signal (top right panel),
whose peaks is then detected (bottom left panel) for the RR
estimation.
[0234] In these exemplary embodiments, the sensor network is
characterized as multi-modal, in that different sensors may be used
to determine a same physiological parameter. This multi-modal input
provides the ability to achieve much more reliable data readouts
and intervention, which is important in critical care applications,
and neonatal care.
[0235] In certain embodiments, pulse oximetry (SpO.sub.2) can be
determined by continuous wavelet transform (CWT) and discrete
saturation transform (DST). FIG. 10 summarizes an algorithm of the
CWT and DST for the pulse oximetry. In the exemplary embodiment,
calculation of SpO.sub.2 involves with algorithms known for an
effective motion artifact reduction, which is critical to calculate
accurate value as babies in NICU and PICU are often fidgeting. Band
pass filtered (f.sub.c1=0.5 Hz, f.sub.c2=5 Hz) and normalized PPG
signals are processed further with the CWT that constructs
continuous time-frequency analysis of the signals. The CWT is
effective in detecting rapid changes in frequency in the time
domain that can be caused by motion-driven artifact, which serves
as the first motion artifact reduction stage. Following with the
power ratio calculation and getting the median value, the signal
processing further suppresses motion artifact by the DST algorithm.
The DST algorithm involves with an adaptive filtering and
determination of family of the reference noise signal and true
signal based on optical density ratio. The adaptive filtering
automatically cancels noise content, which is based off the
pre-determined reference. This series of signal processing is
occurring in real-time to yield an accurate SpO.sub.2 value.
[0236] FIGS. 11A-11B illustrate resultant outcomes of SpO.sub.2 for
a clean signal (without motion artifact) and a noisy signal (motion
contaminated signal), respectively, where a motion-resistant
algorithm is used, which is based on the CWT. A time-frequency
domain (TF) analysis distinguishes real pulsatile response and
motion induced response.
Sensor Performance
[0237] Referring to FIG. 12, for heart rate, the mean difference
from the experimental system compared to standard-of-care system
was -0.47 beats per minute aggregated across 18 subjects, according
to certain embodiments of the invention. The standard deviation of
the mean difference was 3.0 beats per minute. Thus, 95% of the data
fall within a discrepancy less than 6.0 beats per minute. The
agreement of the experimental wireless system remained comparable
at lower heart rates (<100 beats per minute) and higher heart
rates (>170 beats per minute). Referring to FIG. 13, for blood
oxygenation, the mean difference was 0.11% and the standard
deviation of the mean difference was 1.8% between the experimental
system and the standard-of-care system aggregated across 16
subjects, according to certain embodiments of the invention. Thus,
95% of the data fall within a discrepancy less than 3.6% blood
oxygenation. The agreement of the experimental wireless system
remained comparable at both lower blood oxygenation (<90%) as
well as higher blood oxygenation (>96%). Two subjects had
intravenous lines or other medically necessary equipment on both
lower extremities and excluded.
[0238] Referring to FIG. 14, for respiratory rate, the mean
differences was -2.0 breaths per minute with a standard deviation
of mean differences of 8.7 breaths per minute between the
experimental system and the reference system according to certain
embodiments of the invention. The higher variation for respiratory
rate may relate to differences in the measuring modality of
respiratory rate. Respiratory rate derived by the experimental
system is through the ECG while the reference Phillips monitor
utilizes thoracic impedance pneumography). Similar performance is
noted for measurements across low and high respiration rates
(<30 and >70 breaths per minute).
[0239] FIG. 15 shows the heart rate determined by a sensor network
according to certain embodiments of the invention, illustrating the
equivalent performance to an FDA-approved device.
[0240] FIG. 16 illustrates good agreement between an ECG sensor
system according to one embodiment of the invention and an
FDA-approved gold standard device. The top panel shows original
data measured by both the ECG sensor system and the FDA-approved
gold standard device. The middle panel shows a linear calibration
of the data measured by the ECG sensor system and the FDA-approved
gold standard device. After the calibration, as shown in the bottom
panel of FIG. 16, the measurements between the two different
systems are well-correlated, with a difference after calibration of
1.1.+-.1.9. Similar equivalence is illustrated for SpO.sub.2 (%)
and temperature. Such calibration factors may be used in any of the
algorithms, to further improve sensor accuracy.
[0241] FIG. 17 illustrates a fully wireless sensor platform (top
panel) according to one embodiment of the invention and a neonatal
forehead measurement (bottom panel) using an IR wavelength of 860
nm, red wavelength of 660 nm, source detector distance of 3.7 mm
measured by the wireless sensor platform.
Skin Safety
[0242] The sensor network is deployed on two premature and low
birth weight neonates (<2000 g). The first sensor system 1910 is
deployed in the chest adjacent to existing monitoring electrodes.
The second sensor system 1950 is placed on the foot for pulse
oximetry. The standard-of-care pulse oximeter is placed on the
contralateral limb. The first sensor system is placed on the
central chest. The skin underlying the first and second sensor
system 1910 and 1950 shows no visible signs of erythema,
irritation, blistering, or erosions after 15 minutes of sensor
removal, which is illustrated in FIGS. 18A-18B.
[0243] In certain embodiment, the sensor systems are used to
evaluate thermal load provided to the underlying skin. Skin
temperature after 24 hours of a chest-mounted sensor found the
device at 35.4.degree. C. and the skin temperature after removal at
36.9.degree.. This means there is not any substantial heat
generation or transfer to the underlying tissue, as shown in FIG.
19. Similar results are obtained for an appendage sensors mounted
to the foot. Analysis of thermal images of the device and skin
during prolonged use and after removal reveals the sensor systems
do not generate detectable heat.
Temperature
[0244] The left panels of FIG. 20 illustrate two different
configurations for a temperature sensor, as indicated by the arrow.
In the top-left panel, the temperature probe is located with the
auxiliary electrical components. In the bottom left panel, the
temperature probe is moved a distance of about 3 cm from the other
electrical components. The image on the right illustrates mounting
of the device to the skin. The purpose is to further improve the
correlation between device and core temperature measurement.
[0245] FIG. 21 illustrates a temperature sensor calibration for a
chest unit (top panel) and a foot unit (bottom panel). A medical
grade temperature sensor is calibrated with a thermometer,
resulting in temperature precision of the chest unit and the foot
unit of .+-.0.09.degree. C. and .+-.0.08.degree. C., respectively.
FIG. 22 illustrates correlation of temperature measurements showing
the instant temperature sensors in good agreement with a
gold-standard FDA-approved temperature sensors, where the mean
difference is 0.07.degree. C. Temperature measurement results using
the different devices of FIG. 22 are provided in FIG. 23 (top
panel) compared to core temperature. The bottom panel of FIG. 23
illustrates good device agreement with infrared measurement.
Kangaroo Mother Care (KMC)
[0246] In certain embodiments, KMC can be simulated, where the
neonate is placed on the mother's chest, held, or sleeping on a
bed, with position monitored by a sensor network having an
accelerometer in a sensor system, as shown in FIGS. 24-27. FIG. 24
is a graphical representation of three-dimensional sensor position
(x, y, z) for a sleeping, held in arms and held against body in a
KMC position. FIG. 25 shows the average (x, y, z) locations
determined by a sensor system having an accelerometer, for an
infant in different positions reflected by the photographs. FIG. 26
is a graphical representation of the location results for a
sleeping, feeding, holding and KMC position. FIG. 27 is a summary
of the measure (x, y, z) positions according to certain embodiments
of the invention. Furthermore, an accelerometer sensor can be used
to provide a visual reproduction of the baby position with time,
and associating body position with one or more monitored
physiological parameters.
[0247] Burping of a neonate in a clinical study is summarized in
FIG. 28. The information can be compared to a video recording as an
in-lab reference. Previously observed peaks are regenerated, and
are well correlated with a 4 Hz frequency.
[0248] FIG. 29 summarizes a plot of in-lab simulation showing x, y,
z position, as a function of time.
[0249] A variety of algorithms is useful for classifying sensor
data, including sensor positions, as summarized in FIG. 30A. For
example, various supervised learning (SVM, neural network) and
unsupervised learning (e.g., Gaussian mixture model) may facilitate
classification of sensor positions. FIG. 30B shows a flowchart of
an algorithm for classifying the sensor data according to one
embodiment of the invention. Generally, the algorithm for
classifying the sensor data starts with preprocessing (filtering)
raw data. Then the feature extraction is performed on the
preprocessed data, using fast Fourier transform (FFT) and/or
standard deviation (STD). The extracted features can be clustered
by unsupervised learning (e.g., Gaussian mixture model) or by data
labeling and then supervised learning (SVM, neural network).
[0250] For example, for a support vector machine, a supervised
learning algorithm may be implemented. This involves finding a
hyperplane with biggest margin between its offsets that would "cut"
classes of data. The characteristics of SLM is that they are
relatively simple to implement, effective in binary classification,
and can perform both linear and non-linear classification. In one
embodiment, real-time classification can be achieved, such as
related to posture (lie, stand), tilt (KMC, tilted) and movement
(still, move). A real-time plot of these parameters can be
obtained.
[0251] FIG. 31 illustrates data labeling (top panel) for posture,
tilt and movement (total of 8 labels), based on an accelerometer
sensor system, and data extracted from KMC 24-hour data
measurements (middle and bottom panels) according to certain
embodiments of the invention.
User Interface
[0252] According to the invention, the sensor network is highly
configurable and user-friendly, particularly in terms of a user
interface that rapidly and naturally conveys a range of
information. Various examples of the user interface are provided in
FIGS. 32A-38.
[0253] As shown in FIG. 32A, the remote reader may be a handheld
device such as a smartphone, tablet or the like. Of course, the
wireless transmission makes the sensor network compatible with any
number of reader platforms. The reader may display real-time or
stored data. FIG. 32B illustrates displayed parameters related to
ECG, RR, SpO.sub.2, PTT and temperature, including a running
average, instantaneous reading, and time-plotted.
[0254] According to certain embodiments as shown in FIG. 33, the
reader can connect to various sensors, including via a Bluetooth
connection, e.g., Device A, Device B, . . . Device E. Any of a
range of alarm settings (FIG. 34) may be enabled, so that a user of
the reader can be made aware of any signals falling outside a
desired range.
[0255] In addition, patient position can also be displayed, as
shown in FIGS. 35A and 35B, which illustrate a patient on their
back (FIG. 35A) versus more on their side (FIG. 35B). Notes are
readily taken, either written, oral, or by picture/video, as shown
in FIG. 36.
[0256] According to the invention, sensor malfunction occurs, such
as a lead off condition, it can be rapidly conveyed, as shown in
FIG. 37. Further sensor selection, control, and connection,
including fetal and/or maternal, are compatible with the instant
sensor networks, as shown in FIG. 38.
Telemedicine
[0257] FIG. 39 illustrates the telemedical applications of the
sensor network according to one embodiment of the invention. The
sensor network has wireless outputs, with unique patient identifier
information. The output is provided to a reader, which may have a
display unit and processors for further processing the output data.
The processed data may be provided to a physician/clinician and/or
a patient portal, where secure remote logins ensure only authorized
caregivers and persons have access to the data. There may be
two-way communication between the patient/family member and
caregiver. The caregiver may have two-way communication with a
remote site where the patient is located, thereby ensuring
appropriate orders are efficiently and rapidly conveyed to on-sight
caregivers. Accordingly, the sensor outputs can be viewed by both
the neonate's caregivers as well as their providers. The
availability of skilled neonatologists trained in critical care is
limited in developing countries or rural communities. The wearable
sensors in this disclosure could also enable secure
physician/clinician view allowing for eNICU care.
[0258] Referring to FIG. 40, a flowchart summary illustrating the
benefits of measuring a physiological parameter with at least three
different sensors is shown according to one embodiment of the
invention. According to the embodiment of the sensor network, if
all the three sensors obtain a similar reading that is out of a
specified normal range for the parameter, a caregiver is notified
with an alarm. If one sensor is out of a defined agreement range
(e.g., +/-10%, or a user-determined range that may be relevant for
the specific sensors being used and vital sign being measure), a
notification is sent of an aberrant signal for that sensor so that
a remedial action can be taken. Alternatively, if all the sensors
are in agreement that the parameter is outside a "normal" range,
the clinician may be notified so that immediate
intervention/assessment is made. Of course, even while this is
occurring, the sensors may be continuously in operation providing
parameter measurements. For normal operating conditions, the dashed
arrows reflect the sensor network simply continues normal
operation.
[0259] FIG. 41 shows a flow-chart summary similar to that of FIG.
40, but with an additional Sensor 4 accelerometer that is used to
compensate and correct for motion artifacts, thereby further
increasing sensor accuracy and reliability.
[0260] FIG. 42 is a schematic illustration of the wireless
communication and a Bluetooth time synchronization to provide
time-synchronized sensors according to one embodiment of the
invention. In this exemplary embodiment, multiple sensor networks,
e.g., 4210, 4220 and 4230, communicate with each other through, for
example, local network. As disclosed above, each sensor network
4210, 4220 or 4230, has a plurality of sensor systems
spatial-separately attached to torso regions and limb or appendage
regions of a human subject and time-synchronized to each other and
being in wireless communication with each other through, for
example, a private network. Meanwhile, each sensor network 4210,
4220 or 4230 is in in wireless communication with a reader though
Bluetooth. As such configuration, in addition to perform the
measuring and/or monitoring functions as discussed for the human
subject in which the sensor network is deployed, the sensor network
4210, 4220 or 4230 communicates with the others.
[0261] The foregoing description of the exemplary embodiments of
the present invention has been presented only for the purposes of
illustration and description and is not intended to be exhaustive
or to limit the invention to the precise forms disclosed. Many
modifications and variations are possible in light of the above
teaching.
[0262] The embodiments were chosen and described in order to
explain the principles of the invention and their practical
application so as to activate others skilled in the art to utilize
the invention and various embodiments and with various
modifications as are suited to the particular use contemplated.
Alternative embodiments will become apparent to those skilled in
the art to which the present invention pertains without departing
from its spirit and scope. Accordingly, the scope of the present
invention is defined by the appended claims rather than the
foregoing description and the exemplary embodiments described
therein.
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