U.S. patent application number 13/771698 was filed with the patent office on 2013-08-22 for clip sensor device for measurement of vital signs.
This patent application is currently assigned to OXIRATE, INC.. The applicant listed for this patent is Oxirate, Inc.. Invention is credited to Boris TVERSKOY.
Application Number | 20130218025 13/771698 |
Document ID | / |
Family ID | 48982795 |
Filed Date | 2013-08-22 |
United States Patent
Application |
20130218025 |
Kind Code |
A1 |
TVERSKOY; Boris |
August 22, 2013 |
CLIP SENSOR DEVICE FOR MEASUREMENT OF VITAL SIGNS
Abstract
A clip sensor device for optical measuring vital signs of a
subject is provided. The clip sensor device includes a internal
supporting frame formed from an elongated plate configured to be
folded into a desired orientation. A measuring probe is mounted on
an upper surface of the frame. The measuring probe comprises a
transmitter and receiver and configured for generating a time
response of the blood perfused body tissue to the applied optical
signal that is indicative of the vital signs of the subject. The
clip sensor device also includes a pressing member mounted on the
upper surface of the internal supporting frame. The pressing member
includes one or more spring elements configured to provide a
predetermined pressure on the blood perfused body tissue due to the
deformation of the spring elements when said portion of blood
perfused body tissue is applied against the pressing member.
Inventors: |
TVERSKOY; Boris; (Palo Alto,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Oxirate, Inc.; |
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|
US |
|
|
Assignee: |
OXIRATE, INC.
Palo Alto
CA
|
Family ID: |
48982795 |
Appl. No.: |
13/771698 |
Filed: |
February 20, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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61601157 |
Feb 21, 2012 |
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Current U.S.
Class: |
600/476 |
Current CPC
Class: |
A61B 5/0205 20130101;
A61B 5/6838 20130101; A61B 5/14552 20130101; A61B 5/6816 20130101;
A61B 5/6843 20130101 |
Class at
Publication: |
600/476 |
International
Class: |
A61B 5/00 20060101
A61B005/00 |
Claims
1. A clip sensor device for optical measuring at least one vital
sign of a subject, the clip sensor device comprising: a internal
supporting frame configured to be folded into a desired
orientation, and having an upper surface, an under surface, a right
hand end, and a left hand end; a measuring probe mounted on the
upper surface of the internal supporting frame and comprising a
transmitter configured for generating an optical signal and
emitting the optical signal outwardly away from the upper surface
of the internal supporting frame towards a portion of blood
perfused body tissue of the subject, and a receiver configured for
receiving light originated from the portion of blood perfused body
tissue and generating a photo current signal including a time
response of the blood perfused body tissue to the applied optical
signal, the time response is indicative of said at least one vital
sign of the subject; a pressing member mounted on the upper surface
of the internal supporting frame, said pressing member comprising
at least one spring element configured to provide a predetermined
pressure on the portion of the blood perfused body tissue due to
the deformation of the spring element when said portion of blood
perfused body tissue is applied against the pressing member.
2. The clip sensor device of claim 1, wherein said internal
supporting frame includes at least one elongated plate formed from
a hard and formable material suitable to hold the clip sensor
device into said desired orientation and maintain this orientation
during operation of the clip sensor device.
3. The clip sensor device of claim 1, wherein said desired
orientation is a U-shaped orientation.
4. The clip sensor device of claim 1, wherein said internal
supporting frame is made from highly ductile and malleable
metals.
5. The clip sensor device of claim 1, wherein said internal
supporting frame is made from a metal selected from aluminum,
steel, copper and gold.
6. The clip sensor device of claim 1, wherein the transmitter
includes at least one optical emitter selected from a light
emitting diode (LED) and laser diode.
7. The clip sensor device of claim 6, wherein said at least one
optical emitter operates in the red-near infrared spectral range,
such as 600 nm through 1350 nm.
8. The clip sensor device of claim 1, wherein the receiver includes
at least one optical detector selected from a PN photodiode, a PIN
photodiode, an avalanche photodiode (APD), a phototransistor, a
photothyristor, a photomultiplier tube (PMT).
9. The clip sensor device of claim 1, wherein said at least one
optical emitter and said at least one optical detector are both
mounted on the upper surface of the internal supporting frame
adjacent either the right hand end or the right hand end of said
internal supporting frame.
10. The clip sensor device of claim 1, wherein the transmitter is
arranged at one end of the internal supporting frame, whereas the
receiver is arranged at another end of the internal supporting
frame.
11. The clip sensor device of claim 1, wherein said at least one
spring element have a non-Hooke deformation behavior so that the
extension or contraction of said at least one spring element does
not have a linear dependence on the force applied to it.
12. The clip sensor device of claim 1, wherein said at least one
spring element provides a substantially constant force reaction
when subjected to stress.
13. The clip sensor device of claim 1, wherein said at least one
spring element includes a pad made from polyester foam or
ribbon.
14. The clip sensor device of claim 1, wherein said at least one
spring element includes a conical spring.
15. The clip sensor device of claim 1, wherein said measuring probe
is adjacent one end of said internal supporting frame, whereas said
pressing member is adjacent the opposite end of said internal
supporting frame than the measuring probe.
16. The clip sensor device of claim 1, further comprising a housing
enveloping the at least the measuring probe by a covering sleeve,
thereby to protect the measuring probe from damage.
17. The clip sensor device of claim 16, wherein the covering sleeve
further envelopes at least a portion of the internal supporting
frame.
18. The clip sensor device of claim 16, wherein the covering sleeve
extends from the pressing member arranged at one end of the said
internal supporting frame towards another end thereof.
19. The clip sensor device of claim 16, wherein the covering sleeve
includes a window arranged over the measuring probe made of a
material permeable to the radiation generated by the emitter.
20. The clip sensor device of claim 16, wherein the covering sleeve
includes a plurality of V-shaped ribs arranged in the middle of the
clip sensor device.
Description
RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Patent Application No. 61/601,157, filed Feb. 21, 2012, which is
incorporated herein by reference in its entirety.
FIELD OF THE INVENTION
[0002] This invention relates to medical techniques for monitoring
vital signs, and in particular, to a device for measuring vital
signs by detecting light transmitted or reflected from a blood
perfused body tissue.
BACKGROUND OF THE INVENTION
[0003] It is well known in the art to use light transmitted through
or reflected from a medium in order to determine characteristics of
the medium. For example, in the medical field, where non-invasive
physiological monitoring of vital signs of a patient is often
required, light transmitted through a portion of the body, and
reflected or scattered from the body surface may be measured to
determine information about the patient.
[0004] For example, during surgery, blood pressure, heart rate,
breathing rate and blood oxygen saturation are often monitored.
Moreover, for some individuals, there may be a daily, even hourly
need to measure such parameters to know the individuals health
and/or to detect and treat some diseases.
[0005] Furthermore, information about vital signs can also be
important to individuals involved in athletic training and physical
exercising. For example, one of the important applications related
to physical activity is continuous heart rate monitoring. This
field still requires developments in a sense that a suppressive
majority of nowadays optical sensors performing heart rate
monitoring must be attached to body parts, which is inconvenient as
well as relatively unreliable, mainly due to the dependency on
motion-artifacts. Other kinds of related applications are related
to blood pressure monitoring, oximetry, breathing rate monitoring,
etc. Accordingly, the most common requirement for all of the
corresponding monitoring devices is the ability to be stable,
compact, sensitive and reliable under operation with batteries.
[0006] A number of optical monitoring techniques have been proposed
in the art that use light as an optical signal transmitted through
a medium, such as a portion of a blood perfused body tissue with
the goal of determining vital signs. Generally, such a monitoring
system (also known as a photoplethysmograph) includes a transmitter
utilizing a probe clipped on a part of the body (e.g., a finger,
forehead, ear pinna or an earlobe) that includes an optical source,
e.g., a light emitting diode (LED) or a laser, for irradiating the
body part with light placed on one side of the of the body part
while a photodetector is placed on an opposite side of the body
part.
[0007] The monitoring system also includes a receiver utilizing an
optical photodetector (e.g., a photo diode) positioned in an
optical path so that it has a field of view which ensures the
capture of a portion of the light which is transmitted, reflected
or scattered from the body part. The optical detector converts the
light (i.e., optical signal) into an analog electrical signal,
which is subsequently amplified and provided to an analyzer to
retrieve information that was present in the optical signal.
[0008] An example of the medical monitoring device using light
transmitted through a portion of the blood perfused body tissue is
a pulse oximeter. Pulse oximetry is used to determine the oxygen
saturation of arterial blood. Oxyhemoglobin mainly absorbs infrared
light while deoxyhemoglobin mainly absorbs visible red light.
Accordingly, pulse oximeter devices typically contain two types of
light sources, either light emitting diodes or laser diodes,
operating in the red band of light and in the infrared band of
light, respectively. Pulse oximeter devices also include
photo-detectors for each of above mentioned wavebands and the
processing unit that detects the ratio of red/infrared absorption
and calculates the patient's oxygen saturation of arterial
blood.
[0009] Specifically, transmission of optical energy as it passes
through the body is strongly dependent on the thickness of the
material through which the light passes, or the optical path
length. Many portions of a patient's body are typically soft and
compressible. Therefore, when the patient moves, the thickness of
material through which optical energy passes can change. This
results in the changes of the optical path length. For example, if
optical energy passes through a finger and the user of an optical
device moves in a manner which distorts or compresses the finger,
the optical path length changes. Changes in the optical path length
together with the changes of venous blood movement through during
motion can produce enough distortion in the measured signal to make
it difficult or impossible to determine desired information.
[0010] For example, U.S. Pat. Appl. Pub. No. 2009/0227853 describes
an ear hook plethysmography (PPG) sensor and/or pulse oximetry
(SpO.sub.2) sensor that can be attached to the skin in the regions
of superficial artery and vein and posterior auricular artery and
vein around the ear. For example, an ear wearable heart rate
monitor can be constructed with these sensors.
[0011] U.S. Pat. No. 5,551,423 describes a pulse oximeter probe in
the form of a clip that can be attached to an earlobe. The probe
includes a pair of holding members that can be connected together
at an end in such a way that they can pivot on a shaft. The holding
members are arranged with a light-emitting device and a
light-receiving device, in such a way that they are in a
face-to-face relationship. The shaft is fitted with a leaf spring
that urges the light-emitting and light-receiving devices to pivot
in a direction in which they approach each other. The probe can be
attached to an earlobe of a subject by holding the earlobe with the
holding members.
[0012] It was noted that such an oximeter probe of the clip type
has two major drawbacks. First, the holding members have to
compress the earlobe so as to detect the pulsation of blood flowing
in the compressed area but, then, the quantity of blood circulation
decreases to lower the precision of measurement. Second, the probe
which is attached to the earlobe is liable to movements and, hence,
errors due to the movement of the earlobe are most likely to occur
if measurements are done while the subject is walking.
[0013] To avoid these drawbacks, U.S. Pat. No. 5,551,423 providing
a clip pulse oximeter probe that can be attached to the ear of a
subject without compressing the site of measurement, and that is
less sensitive to unwanted movements of the neck. The probe
includes a pair of holding members pivotable on a shaft and
configured for holding the basal part of the earlobe of a subject.
The probe also includes a measuring section that consists of the
light-emitting and light-receiving elements which are provided on
the respective holding members in a face-to-face relationship. The
compressing portions which hold the basal part of the earlobe are
separated in position from the measuring section. One of the two
holding members forms a bent portion at an end that can be inserted
into the entrance to the auditory meatus, whereby the probe can be
securely attached to the ear. In operation, the pulse oximeter
probe detects the pulsation of blood in a blood vessel by reception
of light at a light-receiving element after it is transmitted
through a part of the earlobe.
SUMMARY OF THE INVENTION
[0014] Despite the known techniques in the area of measuring vital
signs by detecting light transmitted or reflected from a portion of
the blood perfused body tissue, there is a need for a novel sensor
probe for robust measurement of vital signs of a subject (e.g.,
human) that can be used in two related areas, such as clinical use
and everyday monitoring of the subject's physical activities. In
both these areas, miniaturization of the measuring devices is
required in order to fabricate them wireless and cost effective, so
that these measuring devices could be deployed to a large
population.
[0015] It would be advantageous to provide a stable miniature stand
alone sensor for robust measurement of vital signs of the user that
will be less vulnerable to motion artifacts under user's motion
conditions such as running and exercising. Moreover, it would be
advantageous if the system will be less vulnerable to optical
coupling between the user's body and the light source as well as
between the user's body and the photo-detector.
[0016] The present invention satisfies the aforementioned needs in
the art by providing a novel clip sensor device for measuring vital
signs of a subject. Example of the vital signs include, but are not
limited to a heart rate, a heart rate variability, an arterial
pulse waveform, a systolic blood pressure, a diastolic blood
pressure, a mean arterial blood pressure, a pulse pressure, a
breathing rate, a total hemoglobin content, and/or a blood oxygen
saturation, etc. The clip sensor device includes an internal
supporting frame formed from an elongated plate configured to be
folded into a desired orientation. When desired, the internal
supporting frame can include two plates connected by a wire or
plurality of wires configured to be folded into a desired
orientation.
[0017] A measuring probe mounted on the upper surface of the
internal supporting frame and comprising a transmitter and
receiver. The transmitter is configured for generating an optical
signal and emitting the optical signal outwardly away from the
upper surface of the internal supporting frame towards a portion of
blood perfused body tissue of the subject. The receiver is
configured for receiving light originated from the portion of blood
perfused body tissue and generating a photo current signal
including a time response of the blood perfused body tissue to the
applied optical signal. The time response is indicative of the
vital signs of the subject.
[0018] The clip sensor device also includes a pressing member
mounted on the upper surface of the internal supporting frame. The
pressing member comprises one or more spring elements configured to
provide a predetermined pressure on the portion of the blood
perfused body tissue due to the deformation of the spring element
when the portion of blood perfused body tissue is applied against
the pressing member.
[0019] According to some embodiments, the internal supporting frame
is formed from a hard and formable material suitable to hold the
clip sensor device into the desired orientation and maintain this
orientation during operation of the clip sensor device.
[0020] According to an embodiment, the desired orientation is a
U-shaped orientation.
[0021] According to some embodiments, the internal supporting frame
is made from highly ductile and malleable metals.
[0022] According to an embodiment, the internal supporting frame is
made from aluminum.
[0023] According to an embodiment, the internal supporting frame is
made from steel.
[0024] According to an embodiment, thickness of the internal
supporting frame is in the range of about 0.3 mm to about 0.8
mm.
[0025] According to an embodiment, the measuring probe is adjacent
the left hand end of said internal supporting frame.
[0026] According to some embodiments, the transmitter includes at
least one optical emitter. Examples of the optical emitter include,
but are not limited to, a light emitting diode (LED) and laser
diode. The optical emitter can, for example, operate in the
red-near infrared spectral range, such as 600 nm through 1350
nm.
[0027] According to some embodiments, the receiver includes at
least one optical detector. Examples of the optical detector
include, but are not limited to, a PN photodiode, PIN photodiode,
avalanche photodiode (APD), phototransistor, photothyristor,
photomultiplier tube (PMT).
[0028] According to some embodiments, the transmitter and receiver
are both mounted on the upper surface of the internal supporting
frame adjacent either the right hand end or the left hand end of
said internal supporting frame.
[0029] According to some embodiments, the transmitter is arranged
at one end of the internal supporting frame, whereas the receiver
is arranged at another end of the internal supporting frame.
[0030] According to some embodiments, the spring element(s) have a
non-Hooke deformation behavior so that the extension or contraction
of the spring element(s) does not have a linear dependence on the
load applied to it.
[0031] According to some embodiments, the spring element(s)
provide(s) a substantially constant force reaction when subjected
to stress.
[0032] According to some embodiments, the spring element(s)
include(s) a pad made from polyester foam or ribbon.
[0033] According to some embodiments, the spring element(s)
include(s) a conical spring.
[0034] According to some embodiments, the measuring probe is
adjacent one end of the internal supporting frame, whereas the
pressing member is adjacent the opposite end of said internal
supporting frame than the measuring probe.
[0035] According to some embodiments, the clip sensor device
further includes a housing enveloping the at least the measuring
probe by a covering sleeve, thereby to protect the measuring probe
from damage.
[0036] According to some embodiments, the covering sleeve further
envelopes at least a portion of the internal supporting frame.
[0037] According to some embodiments, the covering sleeve extends
from the pressing member arranged at one end of the said internal
supporting frame towards another end thereof.
[0038] According to some embodiments, the covering sleeve is made
of a pliable padding material positioned on the upper and under
surfaces surrounding the portion of the internal supporting frame
extending from the pressing member until the right hand end,
thereby encasing the measuring probe.
[0039] According to some embodiments, the covering sleeve includes
at least one material selected from a soft rubber, plastic, a
cloth.
[0040] According to some embodiments, the covering sleeve includes
a window arranged over the measuring probe. The window is made of a
material permeable to the radiation generated by the emitter.
[0041] According to some embodiments, the covering sleeve includes
a plurality of V-shaped ribs arranged in the middle of the clip
sensor device.
[0042] There has thus been outlined, rather broadly, the more
important features of the invention in order that the detailed
description thereof that follows hereinafter may be better
understood. Additional details and advantages of the invention will
be set forth in the detailed description, and in part will be
appreciated from the description, or may be learned by practice of
the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0043] In order to understand the invention and to see how it may
be carried out in practice, a preferred embodiment will now be
described, by way of non-limiting example only, with reference to
the accompanying drawings, in which:
[0044] FIG. 1 illustrates an example of the dependency of an
amplitude of a PPG signal on a contact pressure at the measurement
location;
[0045] FIG. 2 illustrates an exploded perspective view of a clip
sensor device for optic measuring at least one vital sign of a
subject, according to one embodiment of the present
application;
[0046] FIG. 3 illustrates an exploded perspective view of a clip
sensor device for optic measuring at least one vital sign of a
subject, according to another embodiment of the present
application;
[0047] FIG. 4 illustrates an exploded perspective view of a clip
sensor device for optic measuring at least one vital sign of a
subject, according to yet another embodiment of the present
application;
[0048] FIGS. 5A and 5B illustrate the clip sensor device according
to one embodiment of the present application in the unfolded and
U-shape folded configurations, correspondingly; and
[0049] FIG. 6 illustrates an example of the clip sensor device of
the present application attached to an earlobe.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0050] The principles and operation of the a clip sensor device for
measurement of at least one vital sign of a human according to the
present invention may be better understood with reference to the
drawings and the accompanying description, it being understood that
these drawings and examples in the description are given for
illustrative purposes only and are not meant to be limiting. The
same reference numerals and alphabetic characters will be utilized
for identifying those components which are common in the device for
measurement of at least one vital sign of a human and its
components shown in the drawings throughout the present description
of the invention.
[0051] As described above, photoplethysmographic sensors are
typically placed on a subject in a location that is normally
perfused with arterial blood to facilitate measurements of the
desired vital signs. A photoplethysmographic (PPG) signal that is
measured by a photoplethysmograph is a signal produced by arterial
blood volume changes associated with periodic contractions and
relaxations of the heart. A magnitude of the PPG signal is a
function of the amount of the blood ejected from the heart with
every systolic cycle, the optical absorption of blood, absorption
by skin and tissue components, and the specific wavelengths used to
illuminate the vascular tissue bed. During diastole, the blood
volume in the vascular bed decreases, thus to increase the amount
of the light transmitted or backscattered.
[0052] It should be noted that the reliability of the
photoplethysmographic measurements depend on the contact pressure
of a photoplethysmographic sensor on a measurement location. When
the contact pressure used to secure the sensor to the measurement
location on the body is too low, then distorted PPG waveforms can
be generated, that results in inaccurate measurements. On the other
hand, if the contact pressure is too high, then the blood
circulation can be compromised or even necrosis can occur when the
sensor is worn for extended periods of physical activity. When a
blood circulation is slow, the ability to measure Sp0.sub.2 is also
reduced. Moreover, when a too large contact pressure is used, a
complete vessel occlusion can occur, that may lead to a complete
loss of the PPG signal and jeopardize the ability to obtain
Sp0.sub.2, HR and other vital sign data from the measurements. The
optimal contact pressure will result in the greatest AC amplitudes
and SNR will be the highest, which may result in improved
measurement accuracy.
[0053] Referring to FIG. 1, an example of the dependency of an
amplitude of a PPG signal on a contact pressure at the measurement
location (such as a finger) is shown. The PPG amplitudes are
normalized to the largest observed amplitude for each individual.
Each point on the graph represents the mean normalized amplitude
for all 10 individuals. The 95% confidence intervals were
calculated for each point to determine if the observed amplitude
was statistically within an optimal range, which was defined as
pressures yielding normalized amplitudes greater than 0.7. A value
of 0.7 was chosen as the nominal threshold because preliminary data
suggested that this would be the maximal value that could be
statistically identified without relying on extremely large samples
greater than 150.
[0054] Regions 11 and 15 in FIG. 1 indicate contact pressures that
do not provide optimal amplitudes. Regions 12 and 14 represent
instances where the confidence interval produced amplitude values
equal or less than 0.7, therefore, optimal amplitude in these
regions is questionable. A region 13, corresponding to the pressure
in the range of 60 mmHg-80 mmHg, represents optimal contact
pressures.
[0055] In accordance with these experimental results, the present
application provides a novel clip sensor device that can maintain
the contact pressure at a desired magnitude. It should be note that
the desired magnitude of the contact pressure may depend on the
measurement location on the body of a subject. For example, when
the measurements are carried out on a finger, the contact pressure
can be in the range of 60 mmHg-80 mmHg
[0056] Referring to FIG. 2, an exploded perspective view of a clip
sensor device 20 for optic measuring at least one vital sign of a
subject (e.g., a living human) is illustrated, according to one
embodiment of the present invention. Examples of the vital signs
which can be measured by the system of the present application
include, but are not limited to, a heart rate, a heart rate
variability, an arterial pulse waveform, a systolic blood pressure,
a diastolic blood pressure, a mean arterial blood pressure, a pulse
pressure, a breathing rate, a blood oxygen saturation, total
hemoglobin content and/or anaerobic threshold monitoring, etc.
[0057] The clip sensor device 20 includes an internal supporting
frame 21 formed, for example, from an elongated, relatively thin
plate formed from any hard and formable materials suitable to hold
the clip sensor device in a desired orientation. It should be
understood that when desired the frame can be formed from two
plates at the ends 213 and 214 connected to each other by means of
a wire or plurality wires. In particular, materials such as highly
ductile and malleable metals, hard or firm plastic, and the like
that can be bent into a tight U-shape and maintain this shape
during operation can be used as materials suitable for the internal
supporting frame 21. Examples of the metals suitable for internal
supporting frame 31 include, but are not limited to, aluminum,
copper, gold, steel, etc. In particular, when the internal
supporting frame 21 is made of aluminum, it can have thickness in
the range of 0.3 mm-0.8 mm Such provision can make the frame 21
extremely light to minimize motion artifacts during operation of
the clip sensor device 20.
[0058] As shown in FIG. 2, the internal supporting frame 21 has an
upper surface 211, an under surface 212, right hand end 213 and a
left hand end 214. The terms "upper surface", "under surface",
"right hand end", and "left hand end" are used herein for the
purpose of description of a relationship between the different
parts of the internal supporting frame 21 and the clip sensor
device 20, rather than for description of orientation of the sensor
structure in space.
[0059] The clip sensor device 20 also includes a measuring probe 22
mounted on the upper surface 211 of the internal supporting frame
21, adjacent the right hand end 213. According to one embodiment of
the present invention, the measuring probe 22 comprises a
transmitter 23 and a receiver 24. The transmitter 23 includes one
or more optical emitters 231 (only two emitters are shown in FIG.
2) configured for generating an optical signal and emitting the
optical signal outwardly away from the upper surface of the
internal supporting frame 21. Generally, the emitter 231 can be a
light source (e.g. visible, infrared, etc.), an ultra-sonic source,
a microwave source, etc. Examples of the optical emitter 231
include, but are not limited to, emitting diodes (LEDs), laser
diodes, or similar emitting devices.
[0060] Depending on the vital sign selected for determination, the
optical sources may, for example, operate all at the same light
wavelength. According to another embodiment, at least one of the
light sources operates at a different wavelength. For example, for
measurements of heart rate, one or more light emitting sources can
operate at the same wavelength that can be selected within the
transparency window of hemoglobin and water, i.e. in the red-near
infrared spectral range, such as 600 nm through 1000 nm When the
monitoring of total hemoglobin is targeted this range can be
expanded till 1350 nm.
[0061] For measurements of a level of oxygen saturated in blood, at
least two types of light emitting sources operating in the red band
of light and in the infrared band of light are required.
[0062] According to one embodiment of the present invention, the
receiver 24 includes one or more optical detectors 241 (only one
optical detector is shown in FIG. 2) mounted on the upper surface
211 of the internal supporting frame 21, adjacent the right hand
end 213. The optical detector 241 is arranged in the vicinity of
the emitters 231 and configured for receiving light originated from
(i.e., reflected from) at least a portion of the illuminated
measurement location of the subject (not shown). In operation, the
optical detector 241 generates a photo current signal that includes
a time response of the blood perfused body tissue to the applied
optical signal. The time response is indicative of vital signs of
the subject. The optical detector 241 can include one or more
photodiodes or other photo-receiving devices positioned in an
optical path so that a field of view of the optical detector 241
ensures the capture of a portion of the light originated from the
blood perfused body tissue. An example of the suitable photodiode
includes, but is not limited to, a common low-cost PN photodiode, a
PIN photodiode, an avalanche photodiode (APD), phototransistor, a
photothyristor, a photomultiplier tube (PMT), etc. The receiver 24
may include an amplifier (not shown) coupled to the optical
detector 241, and configured to convert the photocurrent generated
by the optical detector 241 into a voltage signal carrying the
information about the vital signs.
[0063] As shown in FIG. 2, the arrangement of the optical emitters
231 and the optical detector 241 with respect to the internal
supporting frame 21 is such that the system 20 can operate with
reflected light. However, when desired, the system 20 can also
operate with transmitted light, mutatis mutandis.
[0064] Referring to FIG. 3, an exploded perspective view of a clip
sensor device 30 for optic measuring at least one vital sign of a
subject is illustrated, according to another embodiment of the
present invention. The clip sensor device 30 differs from the clip
sensor device (20 in FIG. 2) in the fact that one or more optical
emitters 231 are mounted at the right hand end 213 and one or more
optical detector 241 is at the left hand end 214. It can be
understood that this provision of the measuring probe enables
operation with transmitted light.
[0065] The measuring probe 22 is electrically connected through a
hard wired coupling 25 and optionally a connector 26 to external
processing apparatus (not shown) that includes, inter alia, such
modules as an optical signal driver (not shown) coupled to the
transmitter 23 and configured for generating a series of electric
pulses for driving the transmitter 23 by turning it "on" or "off".
The external processing apparatus also includes a demodulator (not
shown) and a control unit configured for adaptive control of the
operation of the measuring probe 22. The processing apparatus can,
for example, be associated with a suitably programmed computer
system (not shown) having, inter alia, such known utilities as a
processor, a memory unit for storing the processed data, and a
monitoring system configured for presenting the measured results of
vital signs. The processor is preprogrammed by a suitable software
model capable of analyzing the received data and determining one or
more desired vital signs. The monitoring system can include a
display, printer and/or other monitoring devices (not shown). When
desired, the monitoring system can include an alarm system to
produce a human detectable signal when a vital sign measurement
generated by the output unit meets predetermined criteria. For
example, the monitoring system can be adapted to create a visual or
audio alarm to alert a user that a detected vital sign is outside
of a predetermined range. When desired the computer system can be
associated with other computer system, which are connected to each
other through a network, for example, through the Internet, thereby
to transmit the measured information about the vital signs to a
desired party.
[0066] The clip sensor device 20 also includes a pressing member 27
mounted on the upper surface 211 of the internal supporting frame
21, adjacent the left hand end 214, however other configurations
are also contemplated. According to one embodiment of the present
invention, the pressing element 27 comprises one or more spring
elements 271, 272 configured to provide a predetermined pressing
force on a surface against which the pressing element 27 is
applied, due to the deformations of the spring elements 271,
272.
[0067] According to the present application the spring elements
271, 272 have a non-Hooke deformation behavior so that the
extension or contraction of spring elements 271, 272 does not have
a linear dependence on the force applied to it. According to an
embodiment of the present invention, the spring elements 271
provide a relatively constant (or close to constant) force reaction
when subjected to stress.
[0068] One type of a device with such properties is the spring
element 272, which is in the form of a pad that is made, for
example, from polyester foam or ribbon. Another type of device with
such properties is the spring element 271, which is a conical
spring, although other elements having non-Hooke deformation
behavior are contemplated. For example, FIG. 2 shows a combined
spring element that includes the conical spring element 271
embedded into the pad spring element 272 made of polyester
foam.
[0069] Referring to FIG. 4, an exploded perspective view of a clip
sensor device 40 for optic measuring at least one vital sign of a
subject is illustrated, according to another embodiment of the
present invention. The clip sensor device 40 differs from the clip
sensor device (20 in FIG. 2) in the fact that the spring elements
271, 272, mounted at the both ends 213 and 214 of the internal
supporting frame 21, respectively. In this case, the measuring
probe 22 can, for example, be arranged within the pad spring
element 272 or mounted on the top of the spring element 271.
[0070] FIGS. 5A and 5B illustrate the clip sensor device 20 in the
unfolded and U-shape folded configurations. In operation, the
internal supporting frame 21 is folded to form a generally U-shaped
configuration. The clip sensor device 20 can be positioned by
bending the internal supporting frame 21 over an anatomical
location of the user's body (e.g., a finger, ear pinna, earlobe,
lip, etc.) 51 with the blood perfused body tissue, and squeezing
near the ends 213 and 214. An example of the clip sensor device 20
attached to an earlobe 61 is shown in FIG. 6.
[0071] In operation, the clip sensor device 20 clamps the
anatomical location, the pressing member 27 is pressed against a
blood perfused body tissue to exert an optimal pressure thereon
over the squeezing range. According to some embodiments, the
optimal pressure is within the range of 60 mmHg-80 mmHg As
described above, the application of the optimal contact pressure
will result in the greatest PPG amplitudes and provide an enhance
measurement accuracy.
[0072] Referring to FIGS. 2, 5A and 5B together, the clip sensor
device 20 can also includes a housing 28 enveloping the measuring
probe 22. The housing 28 can be in the form of a covering sleeve to
protect the measuring probe 22 from damage owing to humidity,
scratching, contacts with foreign objects, and other damaging
factors during exploitation. When desired, at least a portion of
the internal supporting frame 21 can also be enveloped by the
housing (i.e., covering sleeve) 28. As shown in FIG. 2, the
covering sleeve 28 extends from the pressing member 27 towards the
right hand end 213. The covering sleeve 28 is made of a pliable
padding material positioned on the upper and under surfaces 211 and
212 surrounding the portion of the internal supporting frame 21
extending from the pressing member 27 until the right hand end 213,
thereby encasing the measuring probe 22, and provides a conformable
surface for engagement of the clip sensor device 20 with the
measurements location of the subjects body. The covering sleeve 28
can be made from or include, for examples, a soft rubber, plastic,
(such as silicon or polyurethane), cloth and other materials. When
desired, the housing (i.e., covering sleeve) 28 can be fixed to the
internal supporting frame 21 by means of bolts, screws and or
rivets (not shown) via openings 283.
[0073] According to an embodiment, the covering sleeve 28 includes
a window 282 arranged over the measuring probe 22 made of a
material (e.g., glass crystal) permeable to the radiation generated
by the emitter 231 and to the radiation originated from the blood
perfused body tissue for collecting by the detector 241.
[0074] According to an embodiment, the covering sleeve 28 includes
a plurality of V-shaped ribs arranged in the middle of the clip
sensor device 20. As shown in FIG. 5A, the V-shaped ribs prevent
the frame from bending in V-shape and force it to bend in U-shape
protecting the frame from folding it into V-shape. It should be
understood that when a frame receives a V-shape during folding, it
can be broken quicker than in the case when the frame receives
U-shape, since U-shape is less acute and can be folded much larger
times before breaking apart.
[0075] Those skilled in the art to which the present invention
pertains, can appreciate that while the present invention has been
described in terms of preferred embodiments, the concept upon which
this disclosure is based may readily be utilized as a basis for the
designing of other structures, systems and processes for carrying
out the several purposes of the present invention.
[0076] When desired, the clip sensor devices 20, 30 and 40 can be
in the form of a jewelry ring, jewelry ear clip or any other
jewelry item, and have an attractive ornamental appearance. When
desired, the clip sensor devices can be decorated with gemstones,
crystals and/or other decorating items.
[0077] Also, it is to be understood that the phraseology and
terminology employed herein are for the purpose of description and
should not be regarded as limiting.
[0078] Finally, it should be noted that the word "comprising" as
used throughout the appended claims is to be interpreted to mean
"including but not limited to".
[0079] It is important, therefore, that the scope of the invention
is not construed as being limited by the illustrative embodiments
set forth herein. Other variations are possible within the scope of
the present invention as defined in the appended claims. Other
combinations and sub-combinations of features, functions, elements
and/or properties may be claimed through amendment of the present
claims or presentation of new claims in this or a related
application. Such amended or new claims, whether they are directed
to different combinations or directed to the same combinations,
whether different, broader, narrower or equal in scope to the
original claims, are also regarded as included within the subject
matter of the present description.
* * * * *