J1003 U.S. PTO
`
`llilllllilillllllzli/ltillllllllilllil'
`
`"Express Mail" mailing label number ET718932939US.
`Date of Deposit Januam 22, 2002
`
`at 21+ W
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`PATENT APPLICATION TRANSMITTAL LETTER
`
`$1M)?
`
`Case No. 10989-005
`C[-r
`P0
`
`To the Commissioner for Patents:
`
`Sonbol Massoud-Ansari for: WIRELESS CAPACITIVE SENSOR FOR PHYSIOLOGIC PARAMETER MEASUREMENT.
`Enclosed are:
`
`
`Nine (9) sheet(s) of drawings, Thirty-four (34) pages of application (including title page), and the following Appendices :
`
`Declaration.
`
`Power of Attorney.
`
`Verified statement to establish small entity status under 37 CFR §§ 1.9 and 1.27.
`Assignment transmittal letter and Assignment of the invention to :
`Return Postcard.
`
`lZiDEIElDIII
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`Transmitted herewith for filing is the patent application of: Collin A. Rich, Matthew 2. Straayer, Yafan Zhang, Nader Naiafi, and. \E\
`r4: EH
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`lllillilliil
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`Hill
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` Claims as Filed
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`Col. 1
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`a9
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`Basic Fee
`“ 2m "”
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`lflflflfiflflfillllHIIIIIIJIIIII
`Multile De-endent Claims Present
`If the difference in col. 1 is less than zero,
`enter "0" in col. 2.
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`
`
`
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`Please charge my Deposit Account No. 23-1925 in the amount of $: 469.00. A duplicate copy of this sheet is enclosed.
`A check in the amount of $1
`to cover the filing fee is enclosed.
`
`The Commissioner is hereby authorized to charge payment of the following fees associated with this communication or
`credit any overpayment to Deposit Account No. 23—1925. A duplicate copy of this sheet is enclosed.
`E
`Any additional filing fees required under 37 CFR § 1.16.
`B]
`Any patent application processing fees under 37 CFR §1.17.
`
`[I
`
`The Commissioner is hereby authorized to charge payment of the following fees during the pendency of this application or
`credit any overpayment to Deposit Account No. 23—1925. A duplicate copy of this sheet is enclosed.
`[:1
`Any filing fees under 37 CFR § 1.16 for presentation of extra claims.
`
`I]
`
`CI
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`Any patent application processing fees under 37 CFR § 1.17.
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`The issue fee set in 37 CFR § 1.18 at or before mailing of the Notice of Allowance pursuant to 37 CFR
`§ 1.311(b).
`
`'
`
`Registration No. 47, '
`
`
`January 22, 2002
`Date
`
`Rev. Oct-01
`
`Abbott
`ibit 1002
`
`Exh
`
`Page001
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`Abbott
`Exhibit 1002
`Page 001
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`

`

`IN THE UNITED STATES PATENT AND TRADEMARK OFFICE
`
`APPLICATION FOR UNITED STATES LETTERS PATENT
`
`a new and useful invention entitled:
`
`WIRELESS MEMS CAPACITIVE SENSOR
`FOR PHYSIOLOGIC PARAMETER MEASUREMENT
`
`jointly invented by:
`
`Collin A. Rich
`a US. citizen
`
`residing at:
`3530 Cloverlawn Ave., Ypsilanti, MI, 48197
`
`Matthew Z. Straayer
`a U.S. citizen
`
`residing at:
`1001 Miller Ave., Ann Arbor, MI 48103
`
`Yafan Zhang
`a US. citizen
`
`residing at:
`11352 Maple Valley Dr., Plymouth, MI 48170
`
`Nadar Najafi
`a US. citizen
`
`residing at:
`1240 Severn Ct., Ann Arbor, MI 48105
`
`and
`
`Sonbol Massoud-Ansari
`a citizen of Iran
`
`residing at:
`3080 Whisperwood Dr., #475, Ann Arbor, MI 48105
`
`prepared by:
`Eric J. Sosenko
`BRINKS HOFER GILSON & LIONE
`PO. Box 10395
`Chicago, lL 60610
`(734) 302-6000
`
`
`
`Attorney Docket No. 10989—005
`
`Abbott
`Exhibit 1002
`
`Page 002
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`Abbott
`Exhibit 1002
`Page 002
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`

`

`PATENT
`Attorney Docket No. 10989-005
`
`WIRELESS MEMS CAPACITIVE SENSOR FOR
`PHYSIOLOGIC PARAMETER MEASUREMENT
`
`CROSS REFERENCE TO RELATED/APPLICATION
`
`[0001]
`
`This application claims priority to prior U.S. provisional application
`
`number 60/263,327 (filed January 22, 2001) and US. provisional application number
`
`60/278,634 (filed March 26, 2001).
`
`BACKGROUND OF THE INVENTION
`
`1. MW
`
`[0002]
`
`The present invention generally relates to the field of MEMS (micro-
`
`electromechanical systems) sensors and more specifically to a wireless MEMS
`
`capacitive sensor for implantation into the body of a patient to measure one or more
`
`physiologic parameters.
`
`[0003]
`
`A number of different biologic parameters are strong candidates for
`
`continuous monitoring. These parameters include, but are not
`
`limited to blood
`
`pressure, blood flow, intracranial pressure, intraocular pressure, glucose levels, etc.
`
`Wired sensors, if used have certain inherent limitations because of the passage of
`
`wires (or other communication “tethers”) through the cutaneous layer.
`
`Some
`
`limitations include the risks of physical injury and infection to the patient. Another
`
`risk is damage to the device if the wires (the communication link) experience
`
`excessive pulling forces and separate from the device itself. Wireless sensors are
`
`therefore highly desirable for biologic applications.
`
`[0004]
`
`A number of proposed schemes for wireless communication rely on
`
`magnetic coupling between an inductor coil associated with the implanted device
`
`and a separate, external “readout” coil.
`
`For example, one method of wireless
`
`
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`Abbott
`Exhibit 1002
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`Page 003
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`Abbott
`Exhibit 1002
`Page 003
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`

`

`
`
`Attorney Docket No. 10989-005
`
`PATENT
`
`communication (well-known to those knowledgeable in the art) is that of the LC
`
`(inductor-capacitor) tank resonator.
`
`In such a device, a series-parallel connection of
`
`a capacitor and inductor has a specific resonant frequency, expressed as 1/JLC ,
`
`which can be detected from the impedance of the circuit.
`
`If one element of the
`
`inductor-capacitor pair varies with some physical parameter (e.g. pressure), while
`
`the other element remains at a known value,
`
`the physical parameter may be
`
`determined from the resonant
`
`frequency.
`
`For example,
`
`if
`
`the capacitance
`
`corresponds to a capacitive pressure sensor,
`
`the capacitance may be back-
`
`calculated from the resonant frequency and the sensed pressure may then be
`
`deduced from the capacitance by means of a calibrated pressure-capacitance
`
`transfer function.
`
`[0005]
`
`The impedance of an LC tank resonator may be measured directly or it
`
`may also be determined indirectly from the impedance of a separate readout coil
`
`that is magnetically coupled to the internal coil. The latter case is most useful for
`
`biologic applications since the sensing device may be subcutaneously implanted,
`
`while the readout coil may be located external to the patient, but in a location that
`
`allows magnetic coupling between the implanted sensing device and readout coil.
`
`It
`
`is possible for the readout coil (or coils) to simultaneously excite the resonator of the
`
`implanted device and sense the reflected back impedance.
`
`Consequently, this
`
`architecture has the substantial advantage of requiring no internal power source,
`
`which greatly improves its prospects for long-term implantation (e.g. decades to a
`
`human lifetime).
`
`[0006]
`
`Such devices have been proposed in various forms for many
`
`applications.
`
`Chubbuck (U.S. Pat. No. 4,026,276), Bullara (U.S. Pat. No.
`
`2
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`Abbott
`Exhibit 1002
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`Page 004
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`Abbott
`Exhibit 1002
`Page 004
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`

`

`
`
`PATENT
`Attorney Docket No. 10989-005
`
`4,127,110). and Dunphy (US. Pat. No. 3, 958, 558) disclose various devices initially
`
`intended for hydrocephalus applications (but also amenable to others) that use LC
`
`resonant circuits. The ‘276, ‘110, and ‘558 patents, although feasible, do not take
`
`advantage of recent advances in silicon (or similar) microfabrication technologies.
`
`Kensey (US. Pat. No. 6,015,386) discloses an implantable device for measuring
`
`blood pressure in a vessel of the wrist. This device must be “assembled” around the
`
`vessel being monitored such that it fully encompasses the vessel, which may not be
`
`feasible in many cases.
`
`In another application, Frenkel (US. Pat. No. 5,005,577)
`
`describes an implantable lens for monitoring intraocular pressure. Such a device
`
`would be advantageous for monitoring elevated eye pressures (as is usually the
`
`case for glaucoma patients); however, the requirement that the eye's crystalline lens
`
`be replaced will likely limit the general acceptance of this device.
`
`[0007]
`
`In addition to the aforementioned applications that specify LC resonant
`
`circuits, other applications would also benefit greatly from such wireless sensing.
`
`Han, et al. (U.S. Pat. No. 6,268,161) describe a wireless implantable glucose (or
`
`other chemical) sensor that employs a pressure sensor as an intermediate
`
`transducer (in conjunction with a hydrogel) from the chemical
`
`into the electrical
`
`domain.
`
`[0008]
`
`The treatment of cardiovascular diseases such as Chronic Heart
`
`Failure (CHF) can be greatly improved through continuous and/or intermittent
`
`monitoring of various pressures and/or
`
`flows
`
`in
`
`the heart and associated
`
`vasculature. Porat (U.S. Pat. No. 6,277,078), Eigler (US. Pat. No. 6,328,699), and
`
`Carney (US. Pat. No. 5,368,040) each teach different modes of monitoring heart
`
`performance using wireless implantable sensors.
`
`In every case, however, what is
`
`3
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`Abbott
`Exhibit 1002
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`Page 005
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`Abbott
`Exhibit 1002
`Page 005
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`

`

`PATENT
`Attorney Docket No. 10989-005
`
`described is a general scheme of monitoring the heart. The existence of a method
`
`to construct a sensor with sufficient size. long—term fidelity, stability, telemetry range,
`
`and biocompatibiiity is noticeably absent
`
`in each case, being instead simply
`
`assumed. Eigler, et al., come closest to describing a specific device structure
`
`although they disregard the baseline and sensitivity drift
`
`issues that must be
`
`addressed in a long-term implant. Applications for wireless sensors located in a
`
`stent (e.g., U.S. Pat. No. 6,053,873 by Govari) have also been taught, although little
`
`acknowledgement is made of the difficulty in fabricating a pressure sensor with
`
`telemetry means sufficiently small to incorporate into a stent.
`
`[0009]
`
`Closed-loop drug delivery systems, such as that of Feingold (U.S. Pat.
`
`No. 4,871,351) have likewise been taught. As with others, Feingold overlooks the
`
`difficulty in fabricating sensors that meet the performance requirements needed for
`
`long-term implantation.
`
`[0010]
`
`in nearly all of the aforementioned cases, the disclosed devices require
`
`a complex electromechanical assembly with many dissimilar materials, which will
`
`result in significant temperature- and aging-induced drift over time. Such assemblies
`
`may also be too large for many desirable applications, including intraocular pressure
`
`monitoring and/or pediatric applications. Finally, complex assembly processes will
`
`make such devices prohibitively expensive to manufacture for widespread use.
`
`[0011]
`
`As an alternative to conventionally fabricated devices, microfabricated
`
`sensors have also been proposed. One such device is taught by Darrow (U.S. Pat.
`
`No. 6,201,980). Others are reported in the literature (see, e.g. Park, et al., Jpn. J.
`
`Appl. Phys, 37 (1998), pp. 7124—7128; Puers, et al., J. Micromech. Microeng. 1O
`
`
`
`
`
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`Abbott
`Exhibit 1002
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`Page 006
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`Abbott
`Exhibit 1002
`Page 006
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`

`

`PATENT
`Attorney Docket No. 10989-005
`
`(2000). pp. 124-129; Harpster et al., Proc. 14th IEEE lnt’l. Conf. Microelectromech.
`
`Sys. (2001 ), pp. 553—557).
`
`[0012]
`
`Past efforts to develop wireless sensors have separately located the
`
`sensor and inductor and have been limited to implant-readout separation distances
`
`of 1-2 cm at most, rendering them impractical for implantation much deeper than
`
`immediately below the cutaneous layer. This eliminates from consideration wireless
`
`sensing applications, such as heart ventricle pressure monitoring or intracranial
`
`pressure monitoring, that inherently require separation distances in the range of 5~1O
`
`cm.
`
`In the present state-of—the-ait, several factors have contributed to this limitation
`
`on the separation distance including 1) signal attenuation due to intervening tissue,
`
`2) suboptimal design for magnetic coupling efficiency; and 3) high internal energy
`
`losses in the implanted device.
`
`[0013]
`
`in view of the above and other limitations on the prior art. it is apparent
`
`that there exists a need for an improved wireless MEMS sensor system capable of
`
`overcoming the limitations of
`
`the prior art and optimized for signal
`
`fidelity,
`
`transmission distance and manufacturability.
`
`It is therefore an object of the present
`
`invention is to provide a wireless MEMS sensor system in which the sensing device
`
`is adapted for implantation within the body of patient.
`
`[0014]
`
`A further object of this invention is to provide a wireless MEMS sensor
`
`system in which the separation distance between the sensing device and the
`
`readout device is greater than 2 cm, thereby allowing for deeper implantation of the
`
`sensing device within the body of a patient.
`
`
`
`Abbott
`Exhibit 1002
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`Page 007
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`Abbott
`Exhibit 1002
`Page 007
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`

`

`Attorney Docket No. 10989—005
`
`PATENT
`
`[0015]
`
`Still another object of the present invention is to provide a wireless
`
`MEMS sensor system in which the sensing device utilizes an integrated inductor, an
`
`inductor microfabricated with the sensor itself.
`
`[0016]
`
`It is also an object of this invention to provide a wireless MEMS sensor
`
`system in which the sensing device is batteryless.
`
`[0017]
`
`A further object of the present invention is to provide a wireless MEMS
`
`sensor system.
`
`BRIEF SUMMARY OF THE INVENTION
`
`[0018]
`
`In overcoming the limitations of the prior art and achieving the above
`
`objects, the present invention provides for a wireless MEMS sensor for implantation
`
`into the body of a patient and which permits implantation at depths greater than 2 cm
`
`while still readily allowing for reading of the signals from the implanted portion by an
`
`external readout device.
`
`[0019]
`
`In achieving the above, the present invention provides a MEMS sensor
`
`system having an implantable unit and a non-implantable unit. The implantable unit
`
`is microfabricated utilizing common microfabricating techniques to provide a
`
`monolithic device, a device where all components are located on the same chip.
`
`The implanted device includes a substrate on which is formed a capacitive sensor.
`
`The fixed electrode of the capacitive sensor may formed on the substrate itself, while
`
`the moveable electrode of the capacitive sensor is formed as part of a highly doped
`
`silicon layer on top of the substrate. Being highly doped, the silicon layer itself
`
`operates as the conductive path for the moveable electrode. A separate conductive
`
`path is provided on the substrate for the fixed electrode.
`
`
`
`Abbott
`Exhibit 1002
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`Page 008
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`Abbott
`Exhibit 1002
`Page 008
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`

`

`PATENT
`Attorney Docket No. 10989-005
`
`[0020]
`
`In addition to the capacitive sensor,
`
`the implanted sensing device
`
`includes an integrally formed inductor. The integral inductor includes a magnetic
`
`core having at least one plate and a coil defining a plurality of turns about the core.
`
`One end of the coil
`
`is coupled to the conductive lead connected with the fixed
`
`electrode while the other end of the coil is electrically coupled to the highly doped
`
`silicon layer,
`
`thereby utilizing the silicon layer as the conductive path to the
`
`moveable electrode.
`
`[0021]
`
`in order to optimize the operation of the inductor and to permit greater
`
`implantation depths, a novel construction is additionally provided for the magnetic
`
`core.
`
`In general, the optimized magnetic core utilizes a pair of plates formed on
`
`opposing sides of the substrate and interconnected by a post extending through the
`
`substrate. The windings of the coil, in this instance, are provided about the post.
`
`[0022]
`
`The external readout device of the present system also includes a coil
`
`and various suitable associated components, as well known in the field, to enable a
`
`determination of the pressure or other physiologic parameter being sensed by the
`
`implanted sensing device. The external readout device may similarly be utilized to
`
`power the implanted sensing device and as such the implanted sensing device is
`
`wireless.
`
`[0023]
`
`lntegrally formed on the implanted device and mlcrofabricated
`
`therewith, may be additionally be active circuitry for use in conjunction with
`
`capacitive sensor. Locating this circuitry as near as possible to the capacitive
`
`sensor minimizes noise and other factors which could lead to a degradation in the
`
`received signal and the sensed measured physiologic parameter. As such, the
`
`
`
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`Abbott
`Exhibit 1002
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`Page 009
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`Abbott
`Exhibit 1002
`Page 009
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`

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`PATENT
`Attorney Docket No. 10989-005
`
`active circuitry may be integrally microfabricated in the highly doped silicon layer
`
`mentioned above.
`
`[0024]
`
`Further object and advantages of the present invention will become
`
`apparent to those skilled in the art from a review of the drawings in connection with
`
`the following description and dependent claims.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`[0025]
`
`Figure 1
`
`is a schematic illustration of a wireless MEMS sensor system
`
`according the principles of the present invention;
`
`[0026]
`
`Figure 2 is a graphical illustration of impedance magnitude and phase
`
`angle near resonance, as sensed through a readout coil;
`
`[0027]
`
`Figure 3 is a cross-sectional
`
`representation of a sensing device
`
`embodying the principles of the present invention.
`
`[0028]
`
`Figures 4A and 4B are schematic illustrations of the magnetic field
`
`distribution with Figure 4A illustrating the magnetic field distribution of prior art
`
`devices and with Figure 4B illustrating the magnetic field distribution for a sensing
`
`device having a magnetic core embodying the principles of the present invention;
`
`[0029]
`
`Figure 5 is an enlarged cross-sectional view of the diaphragm portion
`
`of Figure 3 operating in what is herein referred to as a "proximity" mode;
`
`[0030]
`
`Figure 6 is a cross-sectional view similar to that seen in Figure 5
`
`illustrating, however, the diaphragm operating in what is herein referred to as a
`
`"touch“ mode;
`
`[0031]
`
`Figure 7 is a capacitance versus pressure curve in the proximity and
`
`touch modes of operation;
`
`
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`Abbott
`Exhibit 1002
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`Page 010
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`Abbott
`Exhibit 1002
`Page 010
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`PATENT
`Attorney Docket No. 10989-005
`
`[0032]
`
`Figure 8 is a top plane view of a second embodiment of the main
`
`electrode in the capacitive sensor portion of the implanted sensing device according
`
`to the principles of the present invention;
`
`[0033]
`
`Figure 9 is a diagrammatic illustration of one scheme for providing
`
`electrically isolated paths for the connections and electrodes of the capacitive sensor
`
`portion;
`
`[0034]
`
`Figure 10 is a diagrammatic illustration of another scheme for
`
`electrically isolating the conductive paths for the connections and contacts of the
`
`capacitive sensor portion;
`
`[0035]
`
`Figure 11 is a cross-sectional view, generally similar to that seen in
`
`Figure 3, further incorporating active circuitry into the sensing device;
`
`[0036]
`
`Figure
`
`12 is a block diagram illustrating one possible circuit
`
`implementation of the active circuitry when incorporated into the sensing device of
`
`the present wireless MEMS sensing system;
`
`[0037]
`
`Figure 13 illustrates one method of mounting, within the body of a
`
`patient, a sensing device embodying the principles of the presents invention;
`
`[0038]
`
`Figure 14 illustrates a second embodiment by which a sensing device
`
`embodying the principles of the present invention may be secured to tissues within
`
`the body of a patient
`
`[0039]
`
`Figures
`
`15
`
`and 16 are diagrammatic
`
`illustrations of different
`
`embodiments for locating a sensing device according to the principles of the present
`
`invention, within a vessel in the body of a patient;
`
`
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`Abbott
`Exhibit 1002
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`Page 011
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`Abbott
`Exhibit 1002
`Page 011
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`

`
`
`Attorney Docket No. 10989-005
`
`PATENT
`
`[0040]
`
`Figure 17 illustrates a sensing device, according to the principles of the
`
`present
`
`invention, encapsulated in a material yielding a pellet—like profile for
`
`implantation into the tissues in the body of a patient;
`
`[0041]
`
`Figure 18 illustrates a sensing device according to the principles of the
`
`present invention being located within the electrode tip of an implantable stimulation
`
`lead, such as that used for cardiac pacing;
`
`[0042]
`
`Figure 19 illustrates a plurality of sensing devices according to the
`
`present
`
`invention located within a catheter and utilized to calculate various
`
`physiologic parameters within a vessel within the body of a patient;
`
`[0043]
`
`Figure 20 is a schematic illustration of multiple sensors being used to
`
`measure performance of a component in the body or a device mounted within the
`
`body of a patient;
`
`[0044]
`
`Figure 21 illustrates a sensing device according to the principles of the
`
`present invention being utilized to measure pressure extemally through a vessel
`
`wall;
`
`[0045]
`
`Figure 22 illustrates a portion of a further embodiment of the present
`
`invention in which the pressure sensing features of the sensing device have been
`
`augmented over or replaced with a structure allowing a parameter other than
`
`pressure to be sensed;
`
`[0046]
`
`Figure 23 is schematic perspective View, with portions enlarged,
`
`illustrating an alternative embodiment for sensing according to the principles of the
`
`present invention; and
`
`[0047]
`
`Figure 24 is an embodiment generally similar to that seen in Figure 23
`
`for sensing according to the principles of the present invention.
`
`10
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`Abbott
`Exhibit 1002
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`Page 012
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`Abbott
`Exhibit 1002
`Page 012
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`

`Attorney Docket No. 10989-005
`
`PATENT
`
`DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
`
`[0048]
`
`In order to provide for battery-less, wireless physiologic parameter
`
`sensing over significant distances greater than 2 cm (e.g. 10 cm),
`
`the present
`
`invention provides a wireless MEMS sensing system, generally designated at 10 and
`
`seen schematically in Figure 1.
`
`The system 10 includes a microfabricated
`
`implantable sensing device 12, optimized for coupling with an external readout
`
`device 14. The sensing device 12 is provided with an integrated inductor 16 that is
`
`conductive to the integration of transducers and/or other components necessary to
`
`construct
`
`the wireless sensing system 10.
`
`As an example,
`
`the preferred
`
`embodiment integrates a capacitive pressure sensor 18 into a common substrate 20
`
`with the integrated inductor 16. A second inductor 24,
`
`in the readout device 14,
`
`couples magnetically 26 with the integrated inductor 16 of the sensing device 12.
`
`[0049]
`
`The readout device 14 is constructed according to techniques well
`
`known in the industry and in the sensing field in general. As such, the readout
`
`device 14 is not illustrated or described in great detail.
`
`It is noted, however, that the
`
`readout device 14 may be included, in addition to its inductor 24, signal conditioning,
`
`control and analysis circuitry and software, display and other hardware and may be
`
`a stand alone unit or may be connected to a personal computer (PC) or other
`
`computer controlled device.
`
`[0050]
`
`The magnetic coupling 26 seen in Figure 1 allows the impedance of
`
`the LC tank circuit 22 to be sensed by the readout device 14. The typical impedance
`
`magnitude 28 and phase angle 30 near resonance 32, as sensed through the
`
`readout coil 14,
`
`is seen in Figure 2. Real—time measurement and analysis of this
`
`11
`
`
`
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`Abbott
`Exhibit 1002
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`Abbott
`Exhibit 1002
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`

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`PATENT
`Attorney Docket No. 10989-005
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`impedance and changes therein allows the sensed pressure to be determined as
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`previously mentioned.
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`[0051]
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`Referring now to Figure 3, a cross section of a preferred embodiment
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`of the sensing device 12 is illustrated therein. The sensing device 12 includes a
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`main substrate 34 (preferably 7740 Pyrex glass) formed and located within recessed
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`regions of the substrate 34 are those structures forming the integrated inductor 16.
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`The integrated inductor 16 is seen to include a magnetic core 33 defined by a top
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`plate 36, a bottom plate 38 and a post 40 connecting the top plate 36 to the bottom
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`plate 38 and being continuous through the substrate 34. The plates 36 and 38 and
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`the post 40 are preferably constructed of the same material, a ferromagnetic
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`material and are monolithic. The integrated conductor 16 additionally includes a coil
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`42, preferably composed of copper or other high—conductivity material, successive
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`turns of which surround the post 40 of the magnetic core 33.
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`[0052]
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`In Figure 3, the coil 42 is seen as being recessed into the top plate 36.
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`The coil 42 may additionally be planar or layered and preferably wraps as tightly as
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`possible about the post 40.
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`if the material of the coil 42 has a high electrical
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`resistance relative to the material of the core 33, (as in a copper coil and NiZn ferrite
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`core system) the core 33, and specifically the top plate 36 may be directly deposited
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`on top of the coil 42 without need for a intermediate insulating layer.
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`If the electrical
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`resistance of the coil material relative to the coil material is not high, an intermediate
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`insulating layer must be included between the successive turns of the coil 42 and the
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`core 33.
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`[0053]
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`Top and bottom cap layers 44 and 46 respectively, are provided over
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`upper and lower faces 48 and 50 of the substrate 20 and over the top and bottom
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`12
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`Abbott
`Exhibit 1002
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`Abbott
`Exhibit 1002
`Page 014
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`

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`Attorney Docket No. 10989—005
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`PATENT
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`plates 36 and 38 of the magnetic core 33. To accommodate any portions of the
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`magnetic core 33 that extend significantly above or below the upper and lower faces
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`48 and 50 of the substrate 20, the cap layers 44 and 46 may be provided with
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`recesses 52 and 54, respectively. Preferably, the cap layers 44 and 46 are of
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`monocrystalline silicon. Other preferred materials include polycrystalline silicon,
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`epitaxially deposited silicon, ceramics, glass, plastics, or other materials that can be
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`bonded to lower substrate and/or are suitable for fabrication of
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`the sensor
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`diaphragm.
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`In lieu of a monolithic cap layer, several sub-pieces may be fabricated
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`at separate process steps, together forming a complete cap layer after processing is
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`finished.
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`[0054]
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`The coupling effectiveness of the integrated inductor 16 is a function of
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`the magnetic flux enclosed by the windings of the coil 42; therefore the coupling is
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`greatest
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`if
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`the structure of
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`the integrated inductor 16 maximizes the flux
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`encompassed by all of the winding loops.
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`Figure 4A shows schematically the
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`magnetic field distribution 56 in a known inductor structure having a single core layer
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`58 and associated windings 60. Schematically shown in Figure 4b is the magnetic
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`field distribution 62 for an inductor structure 16' having upper and lower plates 36'
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`and 38', connected by a post 40' about which windings of a coil 42' are located, as
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`generally seen in the present invention. The design of the present
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`invention
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`optimizes the inductor geometry for maximum field coupling. Placing the plates 36
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`and 38 on opposite sides of the substrate 20, as in Figure 3, increases the plate—to-
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`plate spacing. The increased plate spacing creates a localized path of least
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`resistance for the free—space magnetic field of an external readout coil, causing the
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`magnetic field to preferentially pass through the post 40 of the integrated inductor's
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`13
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`Abbott
`Exhibit 1002
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`Page 015
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`Abbott
`Exhibit 1002
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`PATENT
`Attorney Docket No. 10989-005
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`magnetic core 33. This increases device effectiveness since the coupling efficiency
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`between the sensor and a readout unit increases with the total magnetic flux
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`encompassed by the windings of the inductor. A greater coupling efficiency
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`increases the maximum separation distance between the sensor and a readout unit.
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`[0055]
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`The materials used to form the integrated inductor 16 should be
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`chosen and/or processed to maximize the above mentioned effect and to minimize
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`drift in the inductance value across time, temperature, package stress, and other
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`potentially uncontrolled parameters. A high-permeability material such as NiZn
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`ferrite is used to maximize this effect on the magnetic field and to minimize drift.
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`Other preferred materials
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`include nickel,
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`ferrite, permalloy, or
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`similar
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`ferrite
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`composites.
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`[0056]
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`To the right of the integrated inductor 16 seen in Figure 3 is the
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`capacitive pressure sensor 18.
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`The capacitive pressure sensor 18 may be
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`constructed in many forms commonly know to those familiar with the art.
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`In the
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`illustrated embodiment, the upper cap layer 44 is formed to define a diaphragm 64.
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`The diaphragm 64 constitutes and may also be referred to as the moveable
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`electrode of the pressure sensor 18. The fixed electrode 66 of the pressure sensor
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`18 is defined by a conductive layer formed on the upper face 48 of the substrate 20,
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`in a position immediately below the moveable electrode or diaphragm 64.
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`if desired,
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`a conductive layer may additionally be located on the underside of the moveable
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`electrode 64. To prevent shorting between the upper electrode 64 (as defined by
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`either the diaphragm itself or the diaphragm and the conductive layer 68) and the
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`lower electrode 66, one or both of the electrodes 64 and 66 may be provided with a
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`thin dielectric layer (preferably less than 1000A) deposited thereon.
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`14
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`Exhibit 1002
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`Abbott
`Exhibit 1002
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`PATENT
`Attorney Docket No. 10989-005
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`[0057]
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`To improve performance of the capacitive pressure sensor 18, as seen
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`in Figure 8, one or more secondary electrodes designated at 70 may be located
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`about the fixed electrode 66 near the projected edge of the diaphragm 64 where
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`pressure induced deflection of the diaphragm 64 is minimal.
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`The secondary
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`electrodes 70 experience all of the capacitance-effecting phenomena seen by the
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`main electrode 66, with the exception of any pressure-induced phenomena. The
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`secondary electrodes 70, as such, operate as reference electrodes and by
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`subtracting the secondary electrodes‘ capacitive measurement from the capacitive
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`measurement of
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`the main electrode 66, most or
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`all non-pressure-induced
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`capacitance changes (signal drift) may be filtered out. Examples as sources of
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`signal drift,
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`that may be filtered out by this method,
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`include thermally induced
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`physical changes and parasitics resulting from an environment with changing
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`dielectric constant, such as insertion of the sensor into tissue.
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`In a preferred
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`embodiment, the secondary (or reference) electrodes 70 would require an additional
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`coil, similar to construction of the previously mentioned coil 42 to form a separate LC
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`tank circuit.
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`It is noted, that both coils may, however, share the same core post 40.
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`[0058]
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`Under normal operation, pressure applied to the exterior or top surface
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`of the capacitive pressure sensor 18 causes the diaphragm 64 (or at least the center
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`portions thereof) to deflect downward toward the fixed electrode 66. Because of the
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`change in distance between the fixed electrode 66 and the moveable electrode 64, a
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`corresponding change will occur in the capacitance between the two electrodes.
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`The applied pressure is therefore translated into a capacitance. With this in mind, it
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`is seen that the capacitance pressure sensor 18 may be operated in either of two
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`modes.
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`15
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`Abbott
`Exhibit 1002
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`Abbott
`Exhibit 1002
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`PATENT
`Attorney Docket No. 10989-005
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`[0059]
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`A first mode, hereinafter referred to as the "proximity" mode,
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`is
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`generally seen in Figure 5.
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`In this mode of operation, the starting gap between the
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`fixed electrode 66 and the moveable electrode 64, as well as the material and
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`physical parameters for the diaphragm 64 itself, are chosen such that the fixed
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`electrode 66 and the moveable electrode 64will be spaced apart from one another
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`over the entire operating pressure range of the sensor 18.
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`For the standard
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`equation of parallel plate capacitance, C=£A/d, the plate separation d will vary with
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`the applied pressure, while the plate area A and the permittivity 8 remain constant.
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`[0060]
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`In the touch mode of operation, generally seen in Figure 6,
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`the
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`geometry (e.g., initial gap spacing between the fixed electrode 66 and the moveable
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`electrode 64) as well as the material and physical parameters of the diaphragm 64
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`itself, are chosen such that the fixed electrode 66 and the moveable electrode 64 will
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`progressively touch each other over the operating pressure range of the sensor 18.
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`Accordingly, the area 72 of the fixed electrode 66 and the moveable electrode 64 in
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`contact with each other will vary with the applied pressure.
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`In the touch mode of
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`operation, the dominant capacitance is the capacitance of the regions of the fixed
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`electrode 66 and the moveable electrode 64 in contact with one another (if the
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`dielectric coating 74 is thin compared to the total gap thickness, thereby yielding a
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`relatively small effective plate separation distance d).
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`In the capacitance equation
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`mentioned above, plate separation d and permittivity a will remain constant (at
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`approximately that of the dielectric thickness) while the plate contact area A varies
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`with the applied pressure.
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`[0061]
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`In the graph of Figure 7, capacitance-pressure relationship in