U.S. patent application number 10/995460 was filed with the patent office on 2006-05-25 for disposable wireless pressure sensor.
This patent application is currently assigned to Honeywell International Inc.. Invention is credited to James D. Cook, Peter P. Dierauer, James Z. Liu.
Application Number | 20060107749 10/995460 |
Document ID | / |
Family ID | 35811410 |
Filed Date | 2006-05-25 |
United States Patent
Application |
20060107749 |
Kind Code |
A1 |
Liu; James Z. ; et
al. |
May 25, 2006 |
DISPOSABLE WIRELESS PRESSURE SENSOR
Abstract
In general, a dielectric polymer substrate provided and an
antenna formed upon the dielectric polymer substrate. A
piezoelectric polymer layer (e.g., a polyvinylidene fluoride (PVDF)
piezoelectric film) can be formed above the dielectric polymer
substrate. Additionally, an interdigital (IDT) layer can be
configured upon the PVDF piezoelectric layer, thereby permitting
the piezoelectric polymer layer and the IDT layer to detect
pressure data and transmit the data to a receiver via the
antenna.
Inventors: |
Liu; James Z.; (Rockford,
IL) ; Cook; James D.; (Freeport, IL) ;
Dierauer; Peter P.; (Freeport, IL) |
Correspondence
Address: |
Kris T. Fredrick;Honeywell International, Inc.
101 Columbia Rd.
P.O. Box 2245
Morristown
NJ
07962
US
|
Assignee: |
Honeywell International
Inc.
|
Family ID: |
35811410 |
Appl. No.: |
10/995460 |
Filed: |
November 22, 2004 |
Current U.S.
Class: |
73/754 |
Current CPC
Class: |
G01L 9/0025 20130101;
A61B 2562/02 20130101; A61B 2560/0412 20130101; A61B 5/0215
20130101; A61B 5/0002 20130101 |
Class at
Publication: |
073/754 |
International
Class: |
G01L 9/00 20060101
G01L009/00 |
Claims
1. A disposable sensor system, comprising: a dielectric polymer
substrate and an antenna formed upon said dielectric polymer
substrate; a piezoelectric polymer layer formed above said
dielectric polymer substrate; and an interdigital (IDT) layer
formed upon said piezoelectric polymer layer, thereby permitting
said piezoelectric polymer layer and said IDT layer to detect
pressure data and transmit said data to a receiver utilizing said
antenna.
2. The system of claim 1 further comprising: a bonding layer formed
between said dielectric polymer substrate and said piezoelectric
polymer layer.
3. The system of claim 1 further comprising: a bonding layer formed
between said IDT layer and said piezoelectric polymer layer.
4. The system of claim 1 further comprising a protective cover
layer formed above said IDT layer.
5. The system of claim 1 wherein said IDT layer comprises a
plurality of IDT finger electrodes.
6. The system of claim 5 wherein each of said IDT finger electrodes
among said plurality of IDT finger electrodes comprise copper.
7. The system of claim 1 wherein said dielectric polymer substrate
comprises a gap formed centrally therein, wherein said gap is
filled with a gel comprising a low thermal conductivity and
biocompatible material.
8. The system of claim 1 wherein said piezoelectric polymer layer
comprises a polyvinylidene fluoride (PVDF) piezoelectric film.
9. The system of claim 1 wherein said dielectric polymer substrate
comprises a low thermal conductivity dielectric substrate
material.
10. The system of claim 1 wherein said antenna is printed on said
dielectric polymer substrate.
11. A disposable sensor system, comprising: a dielectric polymer
substrate and an antenna formed upon said dielectric polymer
substrate, wherein said dielectric polymer substrate comprises a
low thermal conductivity dielectric substrate material; a
piezoelectric polymer layer formed above said dielectric polymer
substrate, said dielectric polymer substrate comprises a gap formed
centrally therein, wherein said gap is filled with a gel comprising
a low thermal conductivity and bio-compatible material and wherein
said piezoelectric polymer layer comprises a polyvinylidene
fluoride (PVDF) piezoelectric film; an interdigital (IDT) layer
formed upon said piezoelectric polymer layer, wherein said IDT
layer comprises a plurality of IDT finger electrodes; a protective
cover layer formed above said IDT layer; a first bonding layer
formed between said dielectric polymer substrate and said
piezoelectric polymer layer; and a second bonding layer formed
between said IDT layer and said piezoelectric polymer layer,
thereby permitting said piezoelectric polymer layer and said IDT
layer to detect pressure data and transmit said data to a receiver
utilizing said antenna.
12. A disposable sensor method, comprising the steps: forming an
antenna upon a dielectric polymer substrate; configuring a
piezoelectric polymer layer above said dielectric polymer
substrate; and locating an interdigital (IDT) layer upon said
piezoelectric polymer layer, thereby permitting said piezoelectric
polymer layer and said IDT layer to detect pressure data and
transmit said data to a receiver utilizing said antenna.
13. The method of claim 12 further comprising the step of forming a
bonding layer between said dielectric polymer substrate and said
piezoelectric polymer layer.
14. The method of claim 12 further comprising the step of forming a
bonding layer between said IDT layer and said piezoelectric polymer
layer.
15. The method of claim 12 further comprising the step of forming a
protective cover layer above said IDT layer.
16. The method of claim 12 further comprising the step of
configuring said IDT layer to comprise a plurality of IDT finger
electrodes comprising copper.
17. The method of claim 12 further comprising the steps of: forming
a gap from centrally form said dielectric polymer substrate; and
filling said gap with a gel comprising a low thermal conductivity
and biocompatible material.
18. The method of claim 12 further comprising the step of
configuring said piezoelectric polymer layer as a polyvinylidene
fluoride (PVDF) piezoelectric film.
19. The method of claim 12 further comprising the step of
configuring said dielectric polymer substrate from a low thermal
conductivity dielectric substrate material.
20. The method of claim 12 wherein the step of forming said antenna
upon said dielectric polymer substrate further comprises the step
of printing said antenna on said dielectric polymer substrate.
Description
TECHNICAL FIELD
[0001] Embodiments are generally related to sensing devices and
applications. Embodiments are also related to pressure sensor
devices, systems and methods thereof. Embodiments are additionally
related to disposable sensing devices based on piezoelectric
polymer film materials. Embodiments are additionally related to
medical devices for sensing bodily pressure based on fluid within a
conduit.
BACKGROUND OF THE INVENTION
[0002] A variety of sensors can be utilized to detect conditions,
such as pressure and temperature. The ability to detect pressure
and/or temperature is an advantage to any device exposed to
variable pressure conditions, which can be severely affected by
these conditions. An example of such a device is a catheter, which
of course, can experience variations in both temperature and
pressure. Many different techniques have been proposed for sensing
the pressure and/or temperature in catheters, and for delivering
this information to an operator so that he or she is aware of
pressure and temperature conditions associated with a catheter and
any fluid, such as blood flowing therein.
[0003] One type of sensor that has found wide use in pressure and
temperature sensing applications is the Surface Acoustic Wave (SAW)
sensor, which can be composed of a sense element on a base and
pressure transducer sensor diaphragm that is part of the cover. For
a SAW sensor to function properly, the sensor diaphragm should
generally be located in intimate contact with the sense element at
all pressure levels and temperatures.
[0004] One of the problems with current SAW sensor designs,
particularly those designs adapted to delicate pressure and
temperature sensing applications, is the inability of conventional
SAW sensing systems to meet the demand in low pressure
applications. (e.g., 0 to 500 mmHg), while doing so in an efficient
and low cost manner. Such systems are inherently expensive,
awkward, and often are not reliable in accurately sensing air
pressure and temperature. There is a continuing need to lower the
cost of SAW sensor designs utilized in pressure and/or temperature
sensing applications, particularly wireless pressure sensors.
[0005] To lower the cost and raise efficiency, few components, less
expensive materials and fewer manufacturing-processing steps are
necessary. In order to achieve these goals, it is believed that a
disposable SAW pressure sensor made of polymer substrate should be
implemented, along with low cost processing steps. To date, such
components have not been adequately achieved.
[0006] One area where the ability to detect pressure and/or
temperature is critically important is in the field of medical
applications. Pressure within a conduit, for example, such as a
catheter, can be measured utilizing a number of techniques. Perhaps
the most common device for such measurement is a mechanical gauge,
which can be coupled through one wall of the conduit to the fluid
pressure within the conduit. Inside the gauge, a needle is
deflected over a scale in proportion to the pressure within the
conduit. In some instances, the standard pressure gauge may be
replaced with a transducer, which converts pressure into an
electrical signal, which is then monitored. One important medical
application for a pressure sensor involves detecting a patient's
blood pressure, and/or intracranial pressure.
[0007] One typical method of monitoring blood pressure is to
measure the fluid pressure within an intravenous tube, which is
hydraulically coupled to the patient's vein. A catheter is inserted
into the patient's vein and a plastic tube or conduit coupled to
the catheter. A saline solution can be drip-fed through the plastic
tubing or conduit to maintain a pressure balance against the
pressure within the patient's vein. The saline fluid acts as a
hydraulic fluid to cause the pressure within the plastic tubing to
correspond to the pressure within the patient's vein. Hence, by
measuring the fluid pressure within the tubing, the patient's blood
pressure will be known.
[0008] Various conventional SAW sensing devices are capable of
measuring blood pressure. Such devices typically are configured
from ceramic materials (like PZT), quartz-type piezoelectric
materials or lithium niobate. Such devices are disadvantageous for
medical applications, because the above-referenced materials
utilized by such devices are inherently self-resonant, having
extremely low piezoelectric coupling coefficient, expensive and
difficult for micro-machining, and consequently, grossly reduce the
possibility of making a low cost pressure sensor for medical
applications.
[0009] Conventional quartz-based SAW pressure sensors are also
expensive to implement in medical applications, rendering their
widespread use limited. Micro-machining in quartz is nothing close
to that of silicon. It is therefore believed that a solution to
such problems involves a disposable low cost sensor packaging
system, particularly one that is suited to medical
applications.
BRIEF SUMMARY
[0010] The following summary is provided to facilitate an
understanding of some of the innovative features unique to the
embodiments disclosed herein and is not intended to be a full
description. A full appreciation of the various aspects of the
embodiments discussed herein can be gained by taking the entire
specification, claims, drawings, and abstract as a whole.
[0011] It is, therefore, one aspect of the present invention to
provide for improved sensing devices and applications
[0012] It is another aspect of the present invention to provide for
improved pressure sensor devices, systems and methods thereof.
[0013] It is a further aspect of the present invention to provide
for an improved disposable wireless pressure sensor.
[0014] It is an additional aspect of the present invention to
provide for a pressure sensor system based on interdigital
transducer (IDT) and polymer piezoelectric materials.
[0015] The aforementioned aspects of the invention and other
objectives and advantages can now be achieved as described herein.
Disposable sensor systems and method are disclosed. In general, a
dielectric polymer substrate provided and a microstrip antenna
formed upon the dielectric polymer substrate. A piezoelectric
polymer layer (e.g., a polyvinylidene fluoride (PVDF) piezoelectric
film) and the microstrip antenna can be formed flexible in nature,
which makes them suitable for conformal wraparound designs and
applications. Additionally, an interdigital (IDT) layer can be
configured upon the PVDF piezoelectric layer, thereby permitting
the piezoelectric polymer layer and the IDT layer to detect
pressure data and transmit the data to a receiver via the
antenna.
[0016] A first bonding layer can be formed between the dielectric
polymer substrate and the piezoelectric polymer layer. Also, a
second bonding layer can be formed between the IDT layer and the
piezoelectric polymer layer. A protective cover layer can also be
configured above the IDT layer. The IDT layer can be formed as a
plurality of IDT finger electrodes, which may be configured from
copper. Additionally, the polymer substrate can include a gap
formed centrally therein, such that the gap is filled with a gel
comprising a low thermal conductivity and bio-compatible material.
The polymer substrate is generally formed from a low thermal
conductivity dielectric substrate material.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The accompanying figures, in which like reference numerals
refer to identical or functionally-similar elements throughout the
separate views and which are incorporated in and form a part of the
specification, further illustrate the present invention and,
together with the detailed description of the invention, serve to
explain the principles of the present invention.
[0018] FIG. 1 illustrates a side view of a disposable wireless
pressure sensor system, which can be implemented in accordance with
a preferred embodiment;
[0019] FIG. 2 illustrates a top view of the disposable wireless
pressure sensor system depicted in FIG. 1, in accordance with a
preferred embodiment;
[0020] FIG. 3 illustrates a schematic diagram of a medical pressure
sensing system, which can be implemented in accordance with an
alternative embodiment; and
[0021] FIG. 4 illustrates a schematic diagram of a microstrip
antenna, which can be implemented in accordance with a preferred
embodiment.
DETAILED DESCRIPTION OF THE INVENTION
[0022] The particular values and configurations discussed in these
non-limiting examples can be varied and are cited merely to
illustrate at least one embodiment of the present invention and are
not intended to limit the scope of the invention.
[0023] FIG. 1 illustrates a side view of a disposable wireless
pressure sensor system 100, which can be implemented in accordance
with a preferred embodiment. FIG. 2 illustrates a top view of the
disposable wireless pressure sensor system 100 depicted in FIG. 1,
in accordance with a preferred embodiment. Note that in FIGS. 1-2,
identical or similar parts are generally indicated by identical
reference numerals. System 100 generally includes a dielectric
polymer substrate 102.
[0024] A microstrip antenna 104 can be formed upon the dielectric
polymer substrate 102. Additionally, a piezoelectric polymer layer
106 can be formed above the dielectric polymer substrate, while an
interdigital (IDT) layer 108 can be configured upon the
piezoelectric polymer layer 106, thereby permitting the
piezoelectric polymer layer 106 and the IDT layer 108 to detect
pressure data and transmit the data to a receiver utilizing the
antenna 104. The piezoelectric polymer layer 106 can be configured
as a thin sheet having a thickness in a range of 10-20 microns,
depending upon design considerations.
[0025] Additionally, a first bonding layer 114 can be formed
between the dielectric polymer substrate 102 and the piezoelectric
polymer layer 106. A second bonding layer 112 can be formed between
the IDT layer 108 and the piezoelectric polymer layer 106. First
and second bonding layers 114 and 112 function as adhesives. The
adhesive material for bonding layers 114, 112 can be, for example,
cyano-acrylate or a similar material. The adhesive or bonding layer
thickness for layers 114, 112 can be in a range of approximately 10
to 20 micrometers depending of course upon design
considerations.
[0026] A protective cover layer 110 can be formed above the IDT
layer. The protective cover layer 110 can be formed as a protective
plastic sheet in order to ensure mechanical and chemical protection
of system 100 as a whole. The IDT layer 108 can be configured to
include IDT finger electrodes 116, which are depicted in FIG. 2.
Each of the IDT finger electrodes 116 can be formed from copper.
The copper IDT thickness can be for example, in a range of
approximately 25 micrometers to 125 micrometers, depending upon
design considerations. Note that in order to provide lower
frequency capabilities, a winder line width, along with bigger
device sizes thereof, the IDT finger electrodes can be printed on
the piezoelectric polymer layer 106, or can be electroplated or
etched form a large sheet of IDT finger electrodes thereof.
[0027] The dielectric polymer substrate 102 can also be configured
to include a gap 120 filled with a gel 122 formed from a low
thermal conductivity and biocompatible material. The piezoelectric
polymer layer 106 can be configured as a polyvinylidene fluoride
(PVDF) piezoelectric film, while the dielectric polymer substrate
102 can be formed from a low thermal conductivity dielectric
substrate material. It is believed that the use of PVDF
piezoelectric film in accordance with the preferred embodiment
described herein can result in substantial cost-savings and
increased sensor efficiency, particularly in medical pressure
sensing applications.
[0028] One example where system 100 can be particularly useful is
the field of medical applications, such as blood pressure sensing.
The PVDF piezoelectric film is therefore formed on the
biocompatible low thermal conductivity dielectric polymer substrate
102. The PVDF piezoelectric film changes with temperature and
pressure. Utilizing a low thermal conductivity substrate, for
example, the pyroelectric change by blood can be minimized. The
antenna 104 can be printed on the dielectric polymer substrate.
Thus, in accordance with the preferred embodiment described herein,
a number of transceivers can be provided including a piezoelectric
polymer sheet material, which is less costly and much easier to
work with than conventional pressure sensing devices.
[0029] FIG. 3 illustrates a schematic diagram of a medical pressure
sensing system 300, which can be implemented in accordance with an
alternative embodiment. Note that in FIGS. 1-3, identical or
similar parts or components are generally indicated by identical
reference numerals. Thus, sensor or system 100 of FIG. 1 is also
depicted in FIG. 3 at a location relative to a conduit 301, which
can be implemented as, for example, a catheter through which fluid
303 flow, as indicated by arrows 302 and 304. Fluid 303 can be, for
example, blood. System or sensor 100 can therefore transmit and
receive data to and from a transmitter/receiver 304, which includes
an antenna 306. The wireless transmission of such data is indicated
in FIG. 3 by arrows 308. System 300 can therefore be utilized for
measuring bodily fluid pressure within conduit 301.
[0030] FIG. 4 illustrates a schematic diagram of a microstrip
antenna 400, which can be implemented in accordance with a
preferred embodiment. Microstrip antenna 400 generally includes a
dielectric substrate 404 located above a ground plane 402. A
radiating patch 406 is generally disposed on or in substrate 404.
Note that microstrip antenna 400 of FIG. 4 is analogous to
microstrip antenna 104 of FIG. 1. For example, microstrip antenna
104 can be formed upon a dielectric polymer substrate 102 as
indicated in FIG. 1. Thus, substrate 102 of FIG. 1 is similar to
substrate 404 of FIG. 4.
[0031] Because a dielectric polymer substrate, such as substrate
404 can be flexible, the configuration of microstrip antenna 400 is
suitable for adaptation to conformal wrap-around type designs and
applications. Microstrip antennas, such as antenna 400, offer a
number of advantages compared to conventional microwave antennas
such as, for example light weight, low volume, and thin profile
configurations, which can be made conformal; low fabrication cost;
and readily amendable to mass production. Linear and circular
polarizations are also possible with simple feed configurations.
Additionally, dual-frequency and dual-polarization antennas can be
easily constructed; because, no cavity backing is required and such
devices can be easily integrated with microwave circuits.
[0032] The embodiments and examples set forth herein are presented
to best explain the present invention and its practical application
and to thereby enable those skilled in the art to make and utilize
the invention. Those skilled in the art, however, will recognize
that the foregoing description and examples have been presented for
the purpose of illustration and example only. Other variations and
modifications of the present invention will be apparent to those of
skill in the art, and it is the intent of the appended claims that
such variations and modifications be covered.
[0033] The description as set forth is not intended to be
exhaustive or to limit the scope of the invention. Many
modifications and variations are possible in light of the above
teaching without departing from the scope of the following claims.
It is contemplated that the use of the present invention can
involve components having different characteristics. It is intended
that the scope of the present invention be defined by the claims
appended hereto, giving full cognizance to equivalents in all
respects.
* * * * *