U.S. patent application number 10/848793 was filed with the patent office on 2004-10-28 for skin patch including a temperature sensor.
This patent application is currently assigned to MINI-MITTER COMPANY, INC.. Invention is credited to Barton, Donna K., Bell, Florian G., Laird, Jesse S., Meyer, Thomas Clifton.
Application Number | 20040215098 10/848793 |
Document ID | / |
Family ID | 23019435 |
Filed Date | 2004-10-28 |
United States Patent
Application |
20040215098 |
Kind Code |
A1 |
Barton, Donna K. ; et
al. |
October 28, 2004 |
Skin patch including a temperature sensor
Abstract
A skin patch includes first and second layers of material and a
telesensor sandwiched between the first and second layers. The
first layer has a coating of skin-compatible adhesive material on
its face that is remote from the second layer.
Inventors: |
Barton, Donna K.; (Bend,
OR) ; Bell, Florian G.; (Bend, OR) ; Laird,
Jesse S.; (Bend, OR) ; Meyer, Thomas Clifton;
(Bend, OR) |
Correspondence
Address: |
SMITH-HILL AND BEDELL
12670 N W BARNES ROAD
SUITE 104
PORTLAND
OR
97229
|
Assignee: |
MINI-MITTER COMPANY, INC.
|
Family ID: |
23019435 |
Appl. No.: |
10/848793 |
Filed: |
May 18, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10848793 |
May 18, 2004 |
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10071534 |
Feb 8, 2002 |
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60267593 |
Feb 8, 2001 |
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Current U.S.
Class: |
600/549 ;
128/903; 374/E13.002 |
Current CPC
Class: |
A61B 5/0008 20130101;
G01K 13/20 20210101; Y10S 128/903 20130101; A61B 2562/247 20130101;
A61B 2560/0412 20130101 |
Class at
Publication: |
600/549 ;
128/903 |
International
Class: |
A61B 005/00 |
Claims
1-13. (canceled)
14. A device for acquiring physiological data comprising: a support
layer having first and second opposite main faces and the first
main face having a coating of skin-compatible adhesive material, a
sensor element for sensing a physiological parameter and generating
a signal representative of the physiological parameter, the sensor
element being attached to the support layer at the second main face
thereof, a data storage element for measuring the signal generated
by the sensor element and storing values representing the signal
measurements, and an output means for retrieving the stored
values.
15. A device according to claim 14, wherein the signal generated by
the sensor element represents evolution of the physiological
parameter as a function of time during a measurement period and the
data storage element measures the signal generated by the sensor
element during a measurement period.
16. A device according to claim 14, wherein the signal generated by
the sensor element represents evolution of temperature as a
function of time during a measurement period and the data storage
element measures the signal generated by the sensor element during
a measurement period.
17. A device according to claim 14, wherein the support layer is a
flexible circuit substrate of electrically insulating material.
18. A device according to claim 17, wherein the flexible circuit
substrate is formed with through holes spaced from the sensor
element.
19. A device according to claim 18, wherein the sensor element
includes at least one electrical component attached to the flexible
substrate, and the holes are spaced from said electrical
component.
20. A device according to claim 14, wherein the physiological
parameter is temperature and the signal generated by the sensor
element is a temperature signal.
21. A device according to claim 20, wherein the sensor element
includes an astable multivibrator incorporating a thermistor, the
astable multivibrator generating a square wave output signal having
a duty cycle that depends on the temperature of the thermistor, and
the temperature sensor further comprises a microcontroller that
receives the output signal of the multivibrator and generates said
temperature signal.
22. A device according to claim 14, wherein the support layer
comprises an attachment layer having first and second opposite main
faces, the first main face of the attachment layer being the first
main face of the support layer, and a flexible circuit substrate
having first and second opposite main faces, the first main face of
the flexible circuit substrate being in confronting relationship
with the second main face of said attachment layer and the second
main face of the flexible circuit substrate being the second main
face of the support layer.
23. A device according to claim 14, further comprising a second
layer having first and second main faces, wherein the first main
face of the second layer is in confronting relationship with the
second main face of the support layer and the sensor element is
between the support layer and the second layer.
24. A device according to claim 23, wherein the second layer is a
conformal coating over the sensor element.
25. A device according to claim 23, wherein the second layer is
made of a material that is permeable to water vapor at its first
face and is impermeable to liquid water at its second face.
26. A device according to claim 25, further comprising a conformal
coating of electrically insulating and water impermeable material
over the sensor element.
27. A device according to claim 23, wherein the sensor element is a
temperature sensor and the second layer is made of a thermally
insulating material.
28. A device according to claim 23, wherein the support layer is
made of a material that is permeable to water vapor present at its
first face and the second layer is made of a material that is
permeable to water vapor at its first face and is impermeable to
liquid water at its second face.
29. A device according to claim 14, wherein the support layer is
permeable to water vapor present at its first main face.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims benefit of Provisional Application
No. 60/267,593 filed Feb. 8, 2001. The entire disclosure of
Provisional Application No. 60/267,593 is hereby incorporated by
reference herein for all purposes.
BACKGROUND OF THE INVENTION
[0002] This invention relates to a skin patch including a
telesensor, and particularly to a skin patch that includes a
temperature sensor.
[0003] As used herein, the term "telesensor" means a device that
allows a physiological parameter to be monitored at a distance and
"temperature sensor" means a telesensor for which the physiological
quantity is body temperature. A temperature sensor includes an
element whose behavior depends substantially on temperature of the
element and that emits a signal from which the temperature of the
element can be derived.
[0004] Skin patches have been proposed for several purposes. One
type of skin patch has been used to collect small quantities of
perspiration in an absorbent pad. After the monitoring period, the
patch can be removed from the subject's skin and the perspiration
recovered from the absorbent pad. Through analysis of the
perspiration, the presence and amount of various chemical species
can be determined. For example, U.S. Pat. No. 4,329,999 (Philips)
describes a skin patch useful for drug or alcohol detection. Skin
patches have also been proposed in which chemically active strips
are employed instead of absorbent pads. The strips react to
specific chemicals of interest. For example, U.S. Pat. No.
4,444,193 (Fogt et al) discloses a skin patch in which two
concentric circular reaction areas of chemically treated absorbent
paper reactive to chloride in the perspiration are used for
indicating cystic fibrosis. U.S. Pat. No. 4,732,153 (Philips)
discloses a skin patch containing an active medium such as
charcoal, which traps the perspiration and retains it during the
monitoring period. After monitoring, the active medium is recovered
and analyzed for the presence and amount of the chemical of
interest. Skin patches having multiple test zones containing
different respective active media, for collection and detection of
different chemical species, have also been proposed.
[0005] Skin patches for administering chemicals transdermally have
also been proposed. Skin patches have been developed to administer
medications for pain relief and for hormonal and other replacement
therapies.
SUMMARY OF THE INVENTION
[0006] In accordance with the invention there is provided A skin
patch comprising a first layer of material, the first layer having
first and second opposite main faces and the first main face having
a coating of skin-compatible adhesive material, a second layer of
material, the second layer having first and second opposite main
faces and the first main face of the second layer being in
confronting relationship with the second main face of the first
layer, and a telesensor for emitting a signal that represents a
physiological parameter sensed by the telesensor, the telesensor
being sandwiched between the first and second layers.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] For a better understanding of the invention, and to show how
the same may be carried into effect, reference will now be made, by
way of example, to the accompanying drawings, in which
[0008] FIG. 1 is a top plan view of a first skin patch in
accordance with the present invention; the telesensor is a
temperature sensor and FIG. 1 shows the patch with the cover layer
removed and illustrates the layout of the components of the
temperature sensor,
[0009] FIG. 2 is a schematic sectional view of the skin patch that
is shown in FIG. 1,
[0010] FIG. 3 is a schematic block diagram of the temperature
sensor included in the skin patch shown in FIG. 1, and
[0011] FIG. 4 is a schematic sectional view of a second skin patch
in accordance with the present invention.
DETAILED DESCRIPTION
[0012] The skin patch shown in FIGS. 1-3 includes two integrated
circuit chips 2, 4, two button cell batteries 6 connected to power
supply terminals of the chip 2, and an antenna 8 connected to an
output terminal of the chip 2. The integrated circuit chip 4 is
connected to a thermistor 12 (FIG. 3) and several passive
components (not shown). The electrical resistance of the thermistor
12 depends substantially on its temperature
[0013] The button cells 6 are small and of relatively low profile
and are of the type that are commonly used for hearing aids. The
integrated circuit chips 2, 4 and associated components, the button
cell batteries 6 and the antenna 8 form a temperature sensor. The
temperature sensor, when active, periodically measures the
temperature of the thermistor and then transmits the measurement
information via an RF link. A receiving unit receives the
transmission and derives the temperature.
[0014] The chips 2, 4, the batteries 6 and the antenna 8 are
attached to an electrically insulating flexible circuit substrate
14, as are all other electrical components of the sensor. The
flexible circuit substrate is provided on its undersurface with a
coating 16 of an adhesive material. A removable protective layer 20
of paper adheres to the adhesive coating 16. The skin patch further
includes a top or outer protective layer 22 of thermally insulating
material over the temperature sensor and adhesively bonded to a
peripheral margin of the flexible circuit substrate 14.
[0015] In use of the skin patch, the paper layer 20 is removed to
expose the adhesive coating 16 and the patch is applied to the skin
of a subject. The thermistor temperature equilibrates with skin
temperature of the subject. The temperature sensor, if active,
measures the temperature of the thermistor and transmits the
temperature information.
[0016] In order for the skin patch to be physiologically compatible
with the subject, the material of the adhesive coating should be
one that can remain in contact with the skin for an extended period
of time, e.g. four to five days, without causing an unacceptable
reaction.
[0017] For a normal activity level, moisture transpires through the
skin of a human subject at a moisture vapor transmission rate
(MVTR) of about 425 g/m.sup.2 per 24 hours. Vigorous exercise
produces a higher MVTR while more sedentary behavior results in a
lower MVTR. Moisture that transpires through the skin of a human
subject may adversely affect the electrical components of the skin
patch, i.e. the integrated circuit chips, the cells and the
antenna, and accordingly it is desirable to protect these
components from exposure to such moisture. The flexible circuit
substrate generally has a very low MVTR capacity, so that if the
flexible circuit substrate were imperforate, moisture would not
permeate through the substrate and affect the electrical
components. However, it is not desirable that moisture should be
trapped in contact with the skin and therefore the skin patch must
provide at least sufficient MVTR capacity for normal activity. This
requirement necessitates that each layer of the skin patch have an
MVTR capacity of at least 425 g/m.sup.2 per 24 hours. Moreover, the
upper layer must in addition be resistant to liquid water exposure.
A number of commercially available materials have sufficient MVTR
capacity and are resistant to liquid water.
[0018] Referring to FIG. 1, the patch is sufficiently large, and
the electrical components are sufficiently small, that a
substantial proportion of the area of the flexible circuit
substrate 14 is not occupied by the electrical components. Several
holes 24 through the substrate allow moisture to pass through the
substrate. The holes 24 may be spaced away from the more sensitive
electrical components.
[0019] Moisture that passes through the holes 22 in the substrate
and enters the upper layer 22 will tend to permeate the entire
upper layer. A conformal coating 28 of a polyurethane or epoxy
material is provided over the electrical components in order to
protect them from corrosion and humidity effects due to moisture
present in the upper layer.
[0020] Referring to FIG. 3, the integrated circuit chip 4
implements a timer 32, and the timer 32, the thermistor 12 and
passive components implement an astable multivibrator 30. The
astable multivibrator 30 generates a periodic output signal in the
form of a square wave having a duty cycle that depends on the
resistance of the thermistor 12. The output signal of the
multivibrator 30 is supplied to a microcontroller 34 implemented in
the integrated circuit chip 2. The microcontroller includes a
counter 36, which uses a clock signal generated by an oscillator 38
to measure the length of time in each cycle of the output signal of
the multivibrator for which the output signal is in the logic high
state and the length of time for which the output signal is in the
logic low state, and calculates the ratio of these times. Since the
duty cycle of the output signal depends on the temperature of the
thermistor 12, this ratio also depends on the temperature of the
thermistor. The ratio is encoded by an encoder 40 as a component of
a digital transmission packet. The encoder supplies the digital
transmission packet to a radio transmitter 42 which is also
implemented in the chip 2 and uses the transmission packet to
modulate a carrier and the modulated carrier drives the antenna 8
for radiating the signal.
[0021] The skin patch is used in conjunction with a receiving unit
(not shown) which includes an antenna for receiving the signal
radiated by the transmitting antenna 8, an amplifier for amplifying
the received signal, a microcontroller for decoding the received
signal and recovering the ratio value and calculating temperature
based on the ratio value, a memory for storing calculated
temperature values, and a readout device for displaying the
calculated temperature values.
[0022] In order to prolong shelf life and operating life of the
skin patch, the microcontroller controls supply of power to the
multivibrator 30 and the transmitter 42. The microcontroller 34
further controls its own power consumption by use of low-power
sleep and suspend modes.
[0023] The microcontroller 34 is initially activated to its normal
active mode by applying a specific signal sequence to contact pads
54, which are exposed on the paper layer and are connected to the
microcontroller through vias that pass through the flexible circuit
substrate and the paper layer 20. In the normal mode, the
multivibrator and transmitter are powered. When the microcontroller
has been activated, it periodically returns to and exits from the
suspend mode. In the suspend mode of the microcontroller, the
multivibrator and transmitter are not powered.
[0024] When the skin patch is first assembled, the microcontroller
enters a calibration mode and then enters the low-power sleep mode.
In the sleep mode, the multivibrator and the transmitter are not
powered. From this time until the skin patch is activated, the only
power consumed is that which is required to maintain the
microcontroller in the sleep mode. When the device is to be put to
use, an activator circuit, which may be incorporated in the
receiving unit, applies the wake-up signal sequence to the contact
pads 54. If the proper wake-up signal sequence is detected by the
microcontroller, the microcontroller enters the normal operating
mode, in which it supplies operating current to the multivibrator
and the transmitter for measuring temperature and transmitting
temperature information. The active mode alternates with the
stand-by mode to conserve power when not measuring or
transmitting.
[0025] When the microcontroller detects the proper wake-up signal
sequence, it also powers the multivibrator and the transmitter in
order to measure the temperature, as sensed by the thermistor, and
send a short repeated sequence of measurement data, which includes
a unique identifier for the temperature sensor. This data,
transmitted using the antenna 8, is interpreted by the receiving
unit, which provides the user with an indicator that successful
activation has been achieved. The user can then disconnect the skin
patch from the activation circuit. The paper layer is then removed,
thereby also removing the contact pads 54 and effectively rendering
the activation terminals of the microcontroller inaccessible. The
patch is ready to be applied to the subject's skin.
[0026] After transmitting the measurement and identification data,
the microcontroller removes power from the multivibrator and
transmitter 42 and enters the standby mode. While in this standby
mode, a timer 58 in the microcontroller continues timekeeping
functions and after a predetermined interval wakes the
microcontroller into active mode. The microcontroller activates the
circuits when appropriate and performs the operations described
above in connection with measuring the ratio and transmitting the
encoded data. The microcontroller then removes power, re-enters the
standby mode, and repeats the cycle.
[0027] Further details regarding the operation of the temperature
sensor are disclosed in copending patent application Ser. No.
10/017,098 filed Dec. 12, 2001, the entire disclosure of which is
hereby incorporated by reference herein for all purposes.
[0028] FIG. 4 illustrates a modification of the skin patch
described with reference to FIGS. 1-3. In accordance with FIG. 4,
the coating of physiologically compatible adhesive material is not
provided on the undersurface of the flexible circuit substrate. The
skin patch includes an additional layer 60 adhesively bonded to the
undersurface of the flexible circuit substrate 14 and the adhesive
coating 16 is provided on the undersurface of the layer 60. The
layer 60 is made of a material having an MVTR capacity of at least
425 g/m.sup.2 per 24 hours.
[0029] It will be appreciated that the invention is not restricted
to the particular embodiment that has been described, and that
variations may be made therein without departing from the scope of
the invention as defined in the appended claims and equivalents
thereof. For example, in one alternative embodiment the
microcontroller may be activated by transmitting the wake-up signal
sequence from the activation unit optically instead of
electrically. Further, it would be possible to provide sufficient
memory in the temperature sensor to record temperature measurements
over several days, in which case the stored data could be retrieved
after the measurement period and it might not be necessary to
include a transmitter and an antenna in the temperature sensor.
Although the invention has been described with reference to a
temperature sensor, the invention is also applicable to other
telesensors, for example telesensors that emit signals
representative of heart rate, heart rate interbeat interval,
activity level, including activity level at the sensor location,
and blood oxygen level. Unless the context indicates otherwise, a
reference in a claim to the number of instances of an element, be
it a reference to one instance or more than one instance, requires
at least the stated number of instances of the element but is not
intended to exclude from the scope of the claim a structure or
method having more instances of that element than stated.
* * * * *