U.S. patent application number 10/006357 was filed with the patent office on 2003-06-12 for method and device for measuring physiological parameters at the wrist.
Invention is credited to Cohen, Moshe, Goldreich, Rami, Korman, Doron, Korman, Ronen, Misan, Shai.
Application Number | 20030107487 10/006357 |
Document ID | / |
Family ID | 21720497 |
Filed Date | 2003-06-12 |
United States Patent
Application |
20030107487 |
Kind Code |
A1 |
Korman, Ronen ; et
al. |
June 12, 2003 |
Method and device for measuring physiological parameters at the
wrist
Abstract
A wrist-mounted device for measuring at least one physiological
parameter of the user. The present invention enables such a
measurement to preferably be transformed into clinically useful
information about the user. Such information may then optionally be
sent to medical personnel, for example at a contact and/or
monitoring center, through a gateway device. The gateway device
preferably communicates with the wrist-mounted device of the
present invention through a wireless communication channel.
Inventors: |
Korman, Ronen;
(Petach-Tikva, IL) ; Cohen, Moshe; (Netanya,
IL) ; Korman, Doron; (Kfar Sava, IL) ; Misan,
Shai; (Trieste, IT) ; Goldreich, Rami; (Rosh
Ha'ayin, IL) |
Correspondence
Address: |
DR. D. GRAESER LTD.
C/O THE POLKINGHORNS
9003 FLORIN WAY
UPPER MARLBORO
MD
20772
US
|
Family ID: |
21720497 |
Appl. No.: |
10/006357 |
Filed: |
December 10, 2001 |
Current U.S.
Class: |
340/573.1 ;
340/539.12; 600/301 |
Current CPC
Class: |
A61B 2562/02 20130101;
A61B 5/02438 20130101; A61B 5/11 20130101; A61B 2560/0209 20130101;
A61B 5/0205 20130101; Y10S 128/903 20130101; A61B 5/02055 20130101;
A61B 5/14532 20130101; A61B 5/021 20130101; A61B 5/681 20130101;
A61B 5/14551 20130101; G08B 21/04 20130101; A61B 5/0002 20130101;
A61B 2560/0271 20130101 |
Class at
Publication: |
340/573.1 ;
340/539.12; 600/301 |
International
Class: |
G08B 023/00 |
Claims
What is claimed is:
1. A device for measuring at least one physiological parameter of a
subject, comprising: (a) a fastening article for being fastened to
a wrist of the user; (b) a sensor for measuring at least one
physiological parameter of the user, said sensor being in contact
with at least a portion of said wrist and said sensor being
attached to said fastening article; and (c) a processor for
receiving a signal from said sensor and for converting said at
least one measurement to form medical information.
2. The device of claim 1, wherein said sensor is an analog sensor,
the device further comprising an A/D (analog to digital) converter
for receiving an analog signal from said sensor and for converting
said analog signal to a digital signal, said digital signal being
sent to said processor.
3. The device of claim 2, wherein a rate of sampling by said A/D
converter is determined by said processor.
4. The device of claim 3, wherein said rate of sampling is at least
partially determined according to a type of physiological parameter
being measured.
5. The device of claim 1, wherein said physiological parameter is
heart-related.
6. The device of claim 5, wherein said physiological parameter
includes at least one of heart rate and blood pressure.
7. The device of claim 6, wherein said sensor is selected from the
group consisting of a piezoceramic transducer, a piezoelectric
transducer, a resistive strain gauge and a pressure sensor with
fiber-optic components.
8. The device of claim 5, wherein said physiological parameter
includes variability in heart rate.
9. The device of claim 5, wherein said physiological parameter
includes breathing rate.
10. The device of claim 5, wherein said physiological parameter
includes at least one of arrhythmia and overall cardiac rhythm.
11. The device of claim 5, wherein said physiological parameter
includes body movements.
12. The device of claim 11, wherein said body movements include
presence of abnormal body movements.
13. The device of claim 5, wherein said physiological parameter
includes body temperature.
14. The device of claim 1, further comprising: (d) a non-volatile
memory for storing at least one instruction for execution by said
processor.
15. The device of claim 1, further comprising: (e) a communication
unit for at least transmitting data.
16. The device of claim 15, wherein said communication unit also
transmits a device identifier for uniquely identifying the
device.
17. The device of claim 15, wherein said communication unit also
receives data.
18. The device of claim 1, wherein said fastening article is a
wristband.
19. A system for measuring at least one physiological parameter of
a subject, comprising: (a) a device for measuring the at least one
physiological parameter, comprising: (i) a fastening article for
being fastened to a wrist of the user; (ii) a sensor for measuring
at least one physiological parameter of the user, said sensor being
in contact with at least a portion of said wrist and said sensor
being attached to said fastening article; (iii) a communication
unit for at least transmitting data; and (b) a gateway device for
receiving said transmitted data for being monitored.
20. The system of claim 19, wherein said transmitted data is
monitored manually.
21. The system of claim 20, further comprising: (c) a remote server
in communication with said gateway device, said remote server
providing said transmitted data to a human operator for manual
monitoring.
22. The system of claim 21, wherein at least one of a communication
link between said gateway device and said remote server includes a
telephonic connection.
23. The system of claim 19, wherein said transmitted data is
monitored at least partially automatically by said gateway
device.
24. The system of claim 19, wherein said device and said gateway
device communicate bi-directionally, such that a message
transmitted from said device is acknowledged by said gateway
device, and such that if said gateway device does not acknowledge
correct reception of said message, said device transmits said
message again.
25. The system of claim 19, wherein said device for measuring the
at least one physiological parameter further comprises: (iv) a
processor for receiving a signal from said sensor and for
converting at least one measurement to form medical
information.
26. The system of claim 19, wherein at least one of a communication
link between said device and said gateway device is a wireless
link.
27. The system of claim 19, wherein at least one of a communication
link between said device and said gateway device is a wired
link.
28. The system of claim 19, wherein said communication unit of said
device also receives data, such that communication between said
device and said gateway device includes an acknowledge
procedure.
29. The system of claim 19, wherein said device automatically
performs a measurement of the physiological parameter upon manual
activation of an alarm function by the subject.
30. The system of claim 29, wherein said data is automatically
transmitted to said gateway device upon said manual activation.
31. The system of claim 19, wherein said device automatically and
periodically performs a measurement of the physiological
parameter.
32. The system of claim 31, wherein said data is automatically
transmitted to said gateway device if said measurement is outside
of an acceptable range.
33. The system of claim 32, wherein said measurement is combined
with another measurement of at least one other parameter to
determine if said measurements are outside of said acceptable
range.
34. A method for monitoring a physiological parameter of a user,
comprising: providing a device for monitoring the physiological
parameter, said device being attached to at least a portion of the
user at a pulse point of the user; monitoring the physiological
parameter through said pulse point; and if a level of the
physiological parameter of the user is outside of an expected
range, transmitting an alarm.
35. A device for measuring at least one physiological parameter of
a subject, comprising: (a) a fastening article for being fastened
to a wrist of the user; (b) a piezoceramic sensor for measuring at
least one physiological parameter of the user at a pulse point of
said wrist and said sensor being attached to said fastening
article; and (c) a processor for receiving a signal from said
sensor and for converting said at least one measurement to form
medical information.
Description
FIELD OF THE INVENTION
[0001] The present invention is of a method and device for
measuring at least one physiological parameter of a subject at the
wrist, preferably for extracting clinically useful information
thereof. More specifically, the present invention is of a device
which may be worn at the wrist of the subject with a strap or other
fastening article, and which may then be used to monitor the
subject through measurement of the physiological parameter.
BACKGROUND OF THE INVENTION
[0002] Currently, a number of different types of devices are
available for monitoring human subjects in a non-invasive manner.
For example, heart function can be monitored in a patient through
the use of electrodes which must be attached to the skin of the
patient. Although non-invasive, such equipment is nevertheless
uncomfortable for the patient, who is attached to a network of
cables and wired sensors. In addition, such equipment is very
expensive, limiting its use to hospitals and other medical settings
in which both the cost and the discomfort of the patient can be
justified. Furthermore, patients may become anxious when examined
by medical personnel, thereby significantly altering the normal
readings for these patients.
[0003] However, there are many different situations in which
non-invasive monitoring of a human subject is desired. For example,
such monitoring could be very useful as part of the overall health
maintenance of the human subject, and could be used in order to
detect a deterioration in the physiological condition of the
subject before a concomitant deterioration in the health of the
subject becomes noticeable. Examples of adverse physiological
conditions which could be detected with regular non-invasive
monitoring include but are not limited to excessive weight gain or
less; arrhythmia and other heart conditions; incipient diabetes in
the form of improper glucose metabolism; and loss of lung capacity
or other problems with respiration.
[0004] Heart rate and blood pressure are important factors in
determining the state of a person's health and the physical
condition of a person's body in response to physical or emotional
stress. Periodic monitoring of these physical parameters is
particularly important for individuals having cardiac disease
and/or lowered cardiac functioning, or high blood pressure.
However, physically healthy individuals may also wish to
periodically monitor their heart rate and blood pressure in
stressful situations, for example when engaging in strenuous
exercise.
[0005] In order to support regular monitoring of human subjects in
their normal environment, such as in the home and at the office for
example, the equipment must be non-invasive and easy to use. The
equipment would then be able to monitor at least one physiological
parameter of the user, without requiring the user to perform any
complicated actions and/or to operate complex devices. Indeed, it
would be highly preferred for the equipment to be incorporated as
part of the regular daily living routine of the subject, since the
requirement for any additional or special actions on the part of
human subject is likely to result in decreased compliance. In
addition, the equipment should be robust yet inexpensive.
[0006] One example of such a device incorporates a wristband to
attach a physiological sensor to the wrist of the subject.
Currently, a number of different types of such wristband devices
are available, most of which are intended to be used as stand-alone
devices to provide information about the subject's own physical
condition, mainly for heart rate and blood pressure. Most of these
devices obtain such measurements by using an inflating cuff, which
is bulky and awkward for the subject.
[0007] Wrist-mounted heart rate monitors are known to the art and
have been disclosed, for example, in the patent to Orr et al, U.S.
Pat. No. 3,807,388, wherein the duration of a heart beat is
measured by counting electrical pulses recurring at a known
frequency. The duration of the heartbeat is then related to a
particular average heart beat rate. However, the disclosed
measurement system does not directly measure the heart rate and,
therefore, is subject to inaccuracies of measurement due to the
instability of heart beat duration over brief intervals of
time.
[0008] A blood pressure measuring device is disclosed in the patent
to Petzke et al, U.S. Pat. No. 3,926,179, in which a probe is
applied adjacent to the radial artery of a wrist. A
pressure-sensitive transducer on the probe generates electrical
signals corresponding to the blood pressure pulses of the radial
artery. The electrical pulses are applied to analog circuitry that
generates a systolic signal corresponding to the integrated voltage
at the peak of the electrical pulse signal and a diastolic signal
corresponding to the voltage at the low point of the pulse signal.
The analog device of Petzke et al requires a substantial amount of
power to operate and, therefore, is not suitable for use in a
small, compact stand-alone device for being worn on the wrist.
[0009] A blood pressure and a heart rate measuring wrist watch is
also disclosed in the patent to Broadwater, U.S. Pat. No.
4,331,154, in which a digital watch is employed to measure systolic
and diastolic blood pressure as well as heart rate. The band of the
watch supports a piezoelectric transducer that is held in contact
with the wrist adjacent to the radial artery when a switch on the
band is activated. The absolute values required for this method to
evaluate blood pressure cause the device to be subject to
inaccurate readings, since the tissues of the hand and wrist may be
expected to expand and contract according to such factors as the
time of day, and the condition of the external environment such as
the atmospheric pressure. Such expansion or contraction may cause
different degrees of tension on the wrist-mounted device, which is
therefore not suitable for use without daily calibrations.
[0010] Other wrist-mounted devices are for wireless panic alarm
systems, mainly for elderly people who live alone. These devices
are usually shaped as a wristband or a pendant. Whenever the user
becomes distressed, the user presses a panic button located on the
device. The device then sends a digitally coded wireless message to
a gateway device located nearby, usually in the same room, by using
a unidirectional wireless data communication link. The gateway
device then contacts a manually operated contact center, for
example with a land based or cellular telephone connection. A
particular identifier for the user is usually sent first, after
which the human operator is allowed to talk to the user through a
speaker and to listen through a sensitive microphone located within
the gateway. However, none of the above systems contains any
physiological measurement device within, in order to learn about
the current physiological status of the user.
[0011] In such a situation as described above, the operator at the
call center learns about the user's condition only by speaking with
the user. However, this is only possible if the user is actually
able to speak. High levels of background noise may also prevent the
user from being heard by the microphone of the gateway device.
SUMMARY OF THE INVENTION
[0012] The background art does not teach or suggest a device which
can conveniently, non-intrusively and autonomously measure one or
more physiological parameters, in order to extract medical
information such as heart rate, breathing rate and blood pressure,
and which may be worn on the wrist of the user. The background art
also does not teach or suggest such a wrist-mounted device which
can measure such parameters and then send the information to a
contact center or other location containing medical personnel. The
background art also does not teach or suggest such a wrist-mounted
device which is compact, non-invasive, and light.
[0013] The present invention overcomes these deficiencies of the
background art by providing a wrist-mounted device for measuring at
least one physiological parameter of the user. The present
invention enables such a measurement to preferably be transformed
into medical information about the user, and/or displays the
results on a LCD display. As used herein, the term "physiological
parameter" refers to the signal which is received from the sensor,
while the term "medical information" refers to the information
which may be extracted or otherwise obtained by analyzing this
signal and/or a combination of signals. Such information may then
optionally be sent to medical personnel (for example at a contact
monitoring center) and/or to a remote server, through a gateway
device. The gateway device preferably communicates with the
wrist-mounted device of the present invention through a wireless
communication channel.
[0014] The present invention has the option to display the medical
information to the user on a local LCD display, such that the user
is optionally and preferably able to read the result locally.
[0015] Examples of medical information which may be extracted from
the measured physiological parameter or parameters include, but are
not limited to: heart rate; variability in heart rate; breathing
rate; arrhythmia of the heart (if any), as well as the general
rhythm and functioning of the heart; blood pressure; presence of
abnormal body movements such as convulsions for example; body
position; general body movements; body temperature; presence and
level of sweat; oxygen pressure in the blood; and glucose levels in
the blood.
[0016] Optionally and more preferably, the present invention also
features an alarm signal for being transmitted through the gateway
device in order to indicate an emergency or otherwise dangerous
situation for the user. The alarm signal may optionally be
transmitted according to a manual action of the user, such as
pressing a "panic button" for example.
[0017] Upon receipt of the manually activated alarm signal, the
gateway would preferably initiate immediately a call to a human
operated call center. Then the device would preferably
automatically collect one or more current measurements of
physiological parameters of the user. These measurements may be
sent directly to the gateway, or alternatively may be analyzed in
order to compute the medical information of the user before sending
the results to the gateway. The human operator would then
preferably be able to assess the user's medical condition from the
received information.
[0018] Most preferably, the alarm signal is transmitted
automatically upon measurement of one or more physiological
parameters of the user, preferably even if the user is unable to
press the panic button. Optionally, the alarm signal may be given
to the user, additionally or alternatively, for example by sounding
an audible alarm, more preferably from the wrist-mounted device
itself.
[0019] The device of the present invention also monitors, at least
periodically but more preferably continuously, one or more
physiological parameters of the user. Continuous monitoring would
more easily enable the device to transmit the alarm signal if one
or more physiological parameters are determined to be above
predefined criteria, which may represent such medical information
as unstable or excessive heart rate, or very high or low blood
pressure.
[0020] According to preferred embodiments of the present invention,
the wrist-mounted device features one or more sensors attached to a
wristband or other fastening article. The sensor(s) are preferably
connected to a microprocessor, optionally by a wire but
alternatively through a wireless connection. The microprocessor may
optionally also be located within the wristband, or otherwise
attached to the wristband. The sensor(s) preferably support
automatic collection of the measurement of the at least one
physiological parameter; more preferably, the microprocessor is
able to execute one or more instructions for extracting medical
information about the user from such measurement(s).
[0021] The microprocessor more preferably operates a software
program to process and analyze the data which is collected, in
order to compute medical information. The extracted information,
optionally also with the raw data, is then preferably transferred
to the previously described gateway device. The gateway device then
preferably relays such information to a remote server, which more
preferably is able to provide such information to medical
personnel, for example as part of a contact center. Therefore,
continuous monitoring of the medical information and/or
physiological parameters of the user may optionally and more
preferably be made, enabling better medical care for the user.
According to the present invention there is provided a device for
measuring at least one physiological parameter of a subject,
comprising: (a) a fastening article for being fastened to a wrist
of the user; (b) a sensor for measuring at least one physiological
function of the user, the sensor being in contact with at least a
portion of the wrist and the sensor being attached to the fastening
article; and (c) a processor for receiving a signal from the sensor
and for converting at least one measurement to form the at least
one physiological parameter. Optionally and preferably, the data
may be stored on a non-volatile memory for being downloaded later
by the user or by an operator.
[0022] According to another embodiment of the present invention,
there is provided a system for measuring at least one physiological
parameter of a subject, comprising: (a) a device for measuring the
at least one physiological parameter, comprising: (i) a fastening
article for being fastened to a wrist of the user; (ii) a sensor
for measuring at least one physiological parameter of the user, the
sensor being in contact with at least a portion of the wrist and
the sensor being attached to the fastening article; (iii) a
communication unit for at least transmitting data; and (b) a
gateway device for receiving the transmitted data for being
monitored.
[0023] According to another embodiment of the present invention,
there is provided a method for monitoring a physiological parameter
of a user, comprising: providing a device for monitoring the
physiological parameter, the device being attached to at least a
portion of the user at a pulse point of the user; monitoring the
physiological parameter through the pulse point; and if a level of
the physiological parameter of the user is outside of an expected
range, transmitting an alarm.
[0024] According to still another embodiment of the present
invention, there is provided a device for measuring at least one
physiological parameter of a subject, comprising: (a) a fastening
article for being fastened to a wrist of the user; (b) a
piezoceramic sensor for measuring at least one physiological
parameter of the user at a pulse point of the wrist and the sensor
being attached to the fastening article; and (c) a processor for
receiving a signal from the sensor and for converting the at least
one measurement to form medical information.
[0025] Hereinafter, the term "microprocessor" includes, but is not
limited to, general-purpose microprocessor, a DSP, a
micro-controller or a special ASIC designed for that purpose.
[0026] The method of the present invention could be described as a
process for being performed by a data processor, and as such could
optionally be implemented as software, hardware or firmware, or a
combination thereof. For the present invention, a software
application could be written in substantially any suitable
programming language, which could easily be selected by one of
ordinary skill in the art. The programming language chosen should
be compatible with the computational device (computer hardware and
operating system) according to which the software application is
executed. Examples of suitable programming languages include, but
are not limited to, Visual Basic, Assembler, Visual C, standard C,
C++ and Java.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The invention is herein described, by way of example only,
with reference to the accompanying drawings, wherein:
[0028] FIG. 1 is a schematic block diagram of a system according to
the present invention;
[0029] FIG. 2 shows an exploded view of the device;
[0030] FIG. 3 describes a general state flow diagram; and
[0031] FIG. 4 describes a bi-directional message format between the
device and the gateway.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0032] The present invention is of a wrist-mounted device for
measuring at least one physiological parameter of the user. The
present invention enables such a measurement to preferably be
transformed into medical information about the user. Such
information may then optionally be sent to medical personnel (for
example at a contact monitoring center) and/or to a remote server,
through a gateway device. The gateway device preferably
communicates with the wrist-mounted device of the present invention
through a wireless communication channel.
[0033] Examples of medical information which may be extracted from
the measured physiological parameter or parameters include, but are
not limited to: heart rate; variability in heart rate; breathing
rate; arrhythmia of the heart (if any), as well as the general
rhythm and functioning of the heart; blood pressure; presence of
abnormal body movements such as convulsions for example; body
position; general body movements; body temperature; presence and
level of sweat; oxygen pressure in the blood; and glucose levels in
the blood.
[0034] Optionally and more preferably, the present invention also
features an alarm signal for being transmitted through the gateway
device in order to indicate an emergency or otherwise dangerous
situation for the user. The alarm signal may optionally be
transmitted according to a manual action of the user, such as
pressing a "panic button" for example.
[0035] Most preferably, the alarm signal is transmitted
automatically upon measurement of the one or more physiological
parameters of the user, preferably even if the user is unable to
press the panic button. Optionally, the alarm signal may be given
to the user, additionally or alternatively, for example by sounding
an audible alarm, more preferably from the wrist-mounted device
itself. Upon receipt of the manually/automatically activated alarm
signal, the gateway would preferably initiate immediately a call to
a human operated call center. Then the device would preferably
automatically collect one or more current physiological
measurements of the user. These measurements may be sent directly
to the gateway, or alternatively may be analyzed in order to
compute the medical parameters of the user before sending the
results to the gateway. The human operator would then preferably be
able to assess the user's medical condition from the received
information.
[0036] The device of the present invention may also monitor, at
least periodically but more preferably continuously, the value or
condition of one or more physiological parameters of the user.
Continuous monitoring would more easily enable the device to
transmit the alarm signal if measurements of one or more
physiological parameters are collected and analyzed by the
microprocessor to form medical information, which then could be
determined to be above predefined criteria, such as unstable heart
rate, or very high or low blood pressure, for example.
[0037] According to preferred embodiments of the present invention,
the wrist-mounted device features one or more sensors attached to a
wristband or other fastening article. The sensor(s) are preferably
connected to a microprocessor, optionally by a wire but
alternatively through a wireless connection. The microprocessor may
optionally also be located within the wristband, or otherwise
attached to the wristband. The sensor(s) preferably support
automatic collection of at least one physiological measurement;
more preferably, the microprocessor is able to execute one or more
instructions for extracting clinically useful information about the
user from such measurement(s).
[0038] The microprocessor more preferably operates a software
program to process and analyze the data which is collected, in
order to compute medical information. The extracted medical
information, optionally also with the raw data, is then preferably
transferred to the previously described gateway device. The gateway
device then preferably relays such information to a remote server,
which more preferably is able to provide such information to
medical personnel, for example as part of a contact center.
Therefore, continuous monitoring of the physiological parameters of
the user may optionally and more preferably be made, enabling
better medical care for the user.
[0039] A general, non-limiting example of suitable formulae for
measuring the heart rate and/or other heart-related physiological
parameters of a subject who is wearing the device according to the
present invention may be found in the article "Cuff-less Continuous
Monitoring of Beat-To-Beat Blood Pressure Using Sensor Fusion", by
Boo-Ho Yang, Yi Zhang and H. Harry Asada--IEEE (also available
through http://web.mit.edu/zyi/www/pdf/- IEEETrans2000.pdt as of
Dec. 9, 2001), hereby incorporated by reference as if fully set
forth herein, where systolic and diastolic blood pressure are
calculated using the pulse pressure shape per heartbeat. The
disclosure does not describe a device which has the functionality
according to the present invention, but the disclosed method is
generally useful for determining blood pressure from an external
measurement of pressure from the pulse through the skin of the
subject.
[0040] The principles and operation of a device and method
according to the present invention may be better understood with
reference to the drawings and the accompanying description.
[0041] Referring now to the drawings, FIG. 1 is a schematic block
diagram of a system according to the present invention. As shown, a
system 1 features a wearable device 101 to be worn by a user,
preferably as a wrist-mounted device, for example by being attached
with a wristband or other fastening article to the wrist of the
user. Device 101 features at least one physiological sensor 102 for
measuring at least one physiological parameter of the user. The
function of an exemplary sensor 102 is described in greater detail
below.
[0042] The device 101 also preferably features a vibration sensor
123, preferably a piezoceramic sensor, which is not in direct
contact with the skin of the user. Sensor 123 measures the movement
of the wrist. The output of sensor 123 can be used by a processing
unit 103 to capture the movement of the wrist and to recover some
noise received by sensor 102 which is caused by such movement.
[0043] In order to support processing of the measured physiological
parameter or parameters, processing unit 103 more preferably
includes internal RAM and non-volatile program memory (not shown).
Also more preferably, processing unit 103 includes an extended data
memory 105 located externally to processing unit 103. Processing
unit 103 preferably executes at least one instruction for
processing the data obtained by sensor 102.
[0044] Examples of such processing units 103 include but are not
limited to PIC18LC452 by Microchip Technology Inc., which contains
10 channels of 10 bit A/D converters, a 1.5K bytes of internal RAM
and 32K Bytes of non-volatile program memory.
[0045] Extended memory component 105 is preferably an electrically
erasable non-volatile external memory component. Examples of such a
memory component include but are not limited to FM24CL64-S
(Ramtron, USA), with 64 Kbit of fast access read/write serial
memory for storing temporary data related to the sampled
physiological parameter.
[0046] Device 101 optionally and preferably features a real time
clock 117 in order to provide an accurate time and date for each
measurement, as device 101 can optionally store a few measurements
before transmitting such data and/or information to a gateway
device 110, as described in greater detail below. Stored data
and/or information may also optionally be used for such
applications as reminding the subject to take medication, perform a
medical diagnostic measurement, and so forth. An A/D converter 109
with multiple inputs is also optionally and preferably present if
sensor 102 is an analog sensor, in order to convert the analog
signal to a digital signal.
[0047] Device 101 preferably features an internal communication
unit 104, for at least unidirectional, but more preferably
bi-directional, communication with gateway device 110. Gateway
device 110 also preferably features a communication unit 107.
Communication unit 104 may optionally communicate with
communication unit 107 through a wire or alternatively through a
wireless communication link 121. According to preferred embodiments
of the present invention, gateway device 110 is located relatively
close to the user and hence to device 101, for example by being
located in the same building. As a non-limiting example, gateway
device 110 could optionally be installed in the home of the
user.
[0048] Gateway device 110 also optionally and preferably features a
controller 108 for controlling functions of gateway device 110,
such as communication with device 101 for example.
[0049] Gateway device 110 preferably communicates with a remote
server 114 through a data link 120, which could optionally be a
direct dial-up modem connection with DTMF coding or TCP/IP using
regular LAN or dial-up modem connection to an ISP, for example. In
any case, data link 120 may optionally be a wired or wireless link,
for example through a cellular telephone and/or land-based
telephone system, or a combination thereof.
[0050] Remote server 114 optionally and more preferably features a
system administrator 112, which may be a person (for manual
operation) or a software program (for automatic operation), or a
combination thereof. Remote server 114 also preferably features a
database 113 for storing data received from gateway device 110.
[0051] Device 101 may also feature a manually operated panic alarm
button 116 to be manually activated by the user, for example if the
user is in distress. Device 101 may also optionally feature a LED
display 118, for example in order to indicate of alert activation
or a low battery level.
[0052] Physiological sensor 102 is preferably part of a sensor
assembly. Without wishing to be limited in any way, the following
discussion centers around such a physiological sensor 102 which
contains a piezoceramic transducer for generating an electrical
signal, having an amplitude corresponding to the magnitude of
applied pressure. Therefore, if at least a portion of the
transducer is located adjacent to, and in physical contact with, an
area of the wrist where blood pressure pulses may be detected, the
transducer generates electrical pressure pulses corresponding to
the detected blood pressure pulses. Each of the electrical pressure
pulses preferably defines a maximum voltage over a systolic
interval and a minimum voltage over a diastolic interval.
[0053] Although a piezoceramic sensor is used as a pressure
transducer according to a preferred embodiment of the invention, it
should be appreciated that other transducers known to the art may
be employed without departing from the spirit of the invention.
Examples of such sensors include but are not limited to
piezoelectric transducers, resistive strain gauges and pressure
sensor made of fiber-optic techniques.
[0054] The piezoceramic transducer is desirable for the present
invention since the transducer measures the direct effect of the
pressure exerted within the radial artery, while other transducers,
for example resistive strain gauges, measure secondary effects such
as the strain forces that are applied at the surface of the skin
due to the expansion of the radial artery. Piezoceramic transducers
are also cheaper than piezoelectric transducers but still produce a
high-quality signal.
[0055] As shown with regard to FIG. 1, the analog output of sensor
102 is first preferably treated by an analog front-end 119 which
more preferably contains an analog filter (not shown). As a
non-limiting example, this analog filter preferably has a cutoff of
about 20Hz, a linear phase response, a flat amplitude response up
to 10 Hz and an amplification of about 3 for acquiring the full
spectrum of a typical blood pressure pulse. The filtered signal
then enters A/D converter 109.
[0056] Processing unit 103 preferably controls the operation of A/D
converter 109. When a physiological measurement is initiated, A/D
converter 109 starts sampling the filtered analog signal of sensor
102 from analog front-end 119, preferably at a rate controlled by
processing unit 103. This rate is optionally and more preferably 80
samples per second as to over sample the data by a factor of 4 to
maintain a good quality sampled signal. A/D converter 109
preferably transfers the analog data into a digital coded word,
preferably at resolution of 10 bits per sample.
[0057] Preferably about 30 seconds of data is gathered for each
measurement. Processing unit 103 preferably operates a software
program for examining the validity of the sampled data, in order to
determine whether the data contains some indications of legitimate
physiological data (such as of a blood pressure pulse of an artery)
or alternatively whether the data contains only noise or poor
readings. In the second case, A/D converter 109 preferably starts
sampling the signal again in order to obtain data for measurement.
This process preferably continues until the software determines
that sufficient valid data has been collected or after a few
successive rejections (usually after 3 times).
[0058] Then, the software program preferably performs an algorithm
for calculating some medical parameters from the sampled data, such
as the calculation of systolic and diastolic blood pressure using a
method as disclosed in the previously described U.S. Pat. No.
4,418,700, which is hereby incorporated by reference as if fully
set forth herein.
[0059] The calculated parameters are then preferably stored in
memory 105. The data stored in memory 105 is preferably transmitted
to gateway device 110 periodically, or alternatively or
additionally after manual operation of panic button 116.
[0060] The calculated parameters are also optionally and preferably
displayed on a local LCD display (124), so the user can view the
last medical results locally.
[0061] More preferably, data for all medical parameters that are
sent to remote server (114) are sent according to a security
protocol for maintaining the privacy of the user.
[0062] Furthermore, the software program preferably performs
another algorithm for generating an alert if the medical parameters
have values beyond or otherwise outside of the normal expected
values.
[0063] Although a one-way link from device 101 to gateway device
110 may be used, device 101 preferably features a two-way
communication link as shown for link 121, for establishing more
reliable communication with gateway device 110. Examples of
communication units 104, 107 include but are not limited to a
nRF401 UHF transceiver (Nordic), which operates in the universal
ISM band (433.92 Mhz), an infrared transceiver, and a "Bluetooth"
protocol enabled-transceiver operating bi-directionally in the 2.4
GHz band.
[0064] Device 101 preferably has its own unique identifier, stored
in non-volatile data storage, more preferably in memory 105. Each
time device 101 sends a wireless message to gateway device 110,
device 101 also preferably sends the unique identifier to gateway
device 110, although optionally the identifier may be sent only
periodically, for example once per day. Gateway device 110 also
preferably sends a message to a particular device 101 by including
the device identifier in the message, thereby specifying which such
device should receive the message.
[0065] As previously described, device 101 preferably has its own
real time clock 117. For periodic monitoring of the user, real time
clock 117 is preferably used to provide a time tag for each set of
results. This time tag is very important for continuous monitoring
of the user for long periods of time. By examining the data
recorded over of the user for long period of time, a change or
alteration in the health condition of the user may be detected.
Real time clock 117 may optionally be implemented by separate
hardware such as RTC8564 (EPSON, US) for example, or alternatively
by a software program for operation by processing unit 103.
[0066] Device 101 also preferably features a power source such as a
battery 106, which powers device 101. Examples of suitable
batteries include but are not limited to the silver oxide coin
battery model 386 (Panasonic, Japan) having 150 mAh in capacity
with a pulse burst of 75 mA for a short period of time (about 5 sec
for each pulse). Battery 106 optionally and preferably contains
enough energy to power the device for more than one year of
operation without being replaced.
[0067] FIG. 2 shows an exploded view of the exemplary device
according to FIG. 1. As shown, the device features sensor 102,
shown with the preferred but exemplary implementation of a
piezoceramic sensor as previously described. The device also
optionally and preferably features battery 106, and a push button
316 (for optional implementation of the alarm button of the device
of FIG. 1). Battery 106 may optionally be replaced with a plurality
of smaller batteries (not shown). The device preferably features a
processor 314 (which may optionally be similar or identical to the
processing unit of the device of FIG. 1).
[0068] For this exemplary implementation, sensor 102 is in physical
contact with an anvil 300. Anvil 300 preferably features a
protrusion 302 which presses against the skin of the wrist of the
subject (not shown), more preferably at a pulse point. Protrusion
302 therefore receives pressure with each pulse of the blood of the
subject. This pressure is transduced through anvil 300 to sensor
102, which then emits voltage to form a signal, preferably
according to a linear output.
[0069] This signal is then received by processor 314, which
preferably extracts medical information from the measurement of the
physiological parameter. Processor 314 optionally and preferably
features a crystal oscillator 314, for stabilizing the internal
clock of processor 314. Processor 314 is also preferably in contact
with the real time clock of the device (not shown). Also not shown
are the extended memory, transceiver (communication unit), A/D
converter and analog front end of the device.
[0070] Processor 314, oscillator 312 and push button 316 are all
preferably mounted on a PCB board 308. PCB board 308 is then
preferably sandwiched between battery 106 and a device cover 304.
Device cover 304 preferably features a soft cover, which may be
rubber for example, for enabling the user to locate and depress the
alarm button through push button 316.
[0071] An o-ring 310 is preferably used for waterproof sealing
between the upper and the bottom parts of the device. Anvil 300
then is held between sensor 102 and the skin of the user (not
shown), for example by being affixed to sensor 102 with an adhesive
substance.
[0072] According to an alternative implementation of the device of
FIGS. 1 and 2, sensor 102 and anvil 300 could optionally be located
in the wristband for affixing the device to the wrist of the user
(not shown).
[0073] FIG. 3 is a flow chart of the operation of the device. As
the device software begins operation for the first time, the
software preferably makes some initializations using default
values. Once the device has been initialized, the software
preferably triggers a watchdog function shown as a "Watchdog"
process, and then enters a sleeping mode for saving battery life,
shown as a "Sleep" process.
[0074] If the end of a watchdog time period is reached, the device
is assumed to have a fault in its operation, and a master reset is
preferably initiated automatically.
[0075] The device is preferably "woken up" according to one of
three triggers. First, the device is preferably woken up when the
user presses a panic button manually. This process is shown by the
"Alarm" state. The device then preferably immediately starts a
transmission to the gateway device, containing a distress
indication and the device identifier. Then the device enters a
receiving mode for a few seconds, waiting for acknowledge (ACK)
from the gateway device. This process is shown as a "TX/RX"
state.
[0076] If the acknowledge message is not received within this
period of time a repeated message is initiated. Additional
transmissions are initiated, if necessary. However, if after a
predefined number of repeated times an acknowledge message is not
received, an error message is stored within a log and no more tries
are made. More preferably an indication LED starts blinking for a
few seconds, optionally with an audible alarm. Then, the process
returns to the "Sleep" state.
[0077] After receiving acknowledge, the process turns to
"Supervise" state, where the device collects data from its sensors,
preferably calculates some medical information concerning the
current physiological status of the user. Then, it turns into
"Tx/Rx" state, where the device transmits a message containing the
identifier, and the calculated medical parameters. And if the
received ACK contains no commands it returns to the "Sleep" state,
otherwise it does the command and sends an ACK to the gateway. The
gateway returns an ACK with another command to continue or without
a command to terminate this process. After doing the last command
the device returns to the "Sleep" state.
[0078] In the next case where the device exits its "Sleep" state,
an external real time clock signals the device to execute an
automatic check. Then, the process enters "Supervise" state as
discussed in the above paragraph, only that this time for saving
battery life, the device initiate the "Tx/Rx" process only once for
a few successive times sending all the accumulated data in one
transmission. Then, the device preferably enters a "Sleep" state
unless the measured parameters exceed a predefined threshold at
least once, but preferably for a few successive measurements. In
this case, the device initiates an automatic alarm entering the
"Alarm" state, if the device has permission to do so, as previously
described.
[0079] When a timer for a supervise process has been running or
after an alarm, the device preferably exercises an automatic check
as described above, and after that initiates a transmission to the
gateway device including all the data collected after the last
transmission. Then the device preferably waits for acknowledge,
preferably repeating the transmission again if not receiving such
an acknowledge message. In the acknowledge message, a command for
the device can be stored. In such a case the device performs this
command and then it sends an acknowledge message to the gateway
device. This process may optionally continue until an acknowledge
message without a command is received, after which the device
preferably returns to sleep mode.
[0080] In the third case, the device exit "Sleep" mode if of
technical reasons a technician wants to change the operation
software, the device enters "Boot Loader" state where a new
software is loaded "on the fly" without a need to disconnect the
batteries.
[0081] FIG. 4 describes an exemplary message format for exchanging
messages between the device and the gateway device. Every message
preferably starts with a preamble STX byte (hex 7E), followed by a
byte which contains the number of bytes in the current message, and
three bytes of address, followed by a command byte and its
corresponding data bytes. This is followed by two bytes of CRC and
an ETX byte (hex 7B).
[0082] As such, the message is a variable length message with
strong error detection and correction method for enhanced
communication reliability. Each message optionally and preferably
contains a low battery indication, if necessary.
[0083] In case of a unidirectional communication link between the
device and the gateway, a repeated message is preferably
transmitted for a predefined number of times, such as 20 times for
example, after which the device preferably enters a sleeping mode
if no answer is received.
[0084] In case of a bi-directional link, for each message sent to
the gateway device, an acknowledge message is preferably returned
by the gateway device and vise versa. This message may also contain
a command for the device encoded in the CMD byte within the
message. Commands could optionally include, but are not limited to,
one or more of the following:
[0085] 1) Get/Set service type
[0086] 2) Get/Set device ID
[0087] 3) Set interval between successive medical checking
[0088] 4) Set interval between successive supervision
transmissions
[0089] 5) Set Time and date
[0090] 6) Set threshold for automatic alerts
[0091] 7) Set device calibration
[0092] Each time the device sends a message to the gateway, it may
optionally contain a Battery OK/Battery Low indication for the
battery situation. This signal preferably appears three months
before the battery finishes, enough time to ask the user to replace
the battery.
[0093] Each time the device sends a supervise-type message to the
gateway, it preferably sends also all the medical data stored in
its memory with that message.
[0094] Each time the gateway device sends a command back to the
device, the device preferably returns an acknowledge message with a
3 bit message serial number to the gateway device, in order to
fulfill a full handshake between the two. If the gateway device
does not receive acknowledge from the device within a few seconds,
the gateway device preferably sends its transmission message again
with the same serial number. The message may even be repeated a few
times, each time waiting for acknowledge. If acknowledge is not
received, a logbook is updated with an error message, and more
preferably an indication LED is turned on for error indication.
[0095] It will be appreciated that the above descriptions are
intended only to serve as examples, and that many other embodiments
are possible within the spirit and the scope of the present
invention.
* * * * *
References