(12) United States Patent
`Allen et al.
`
`USOO6278.379B1
`(10) Patent No.:
`US 6,278.379 B1
`(45) Date of Patent:
`Aug. 21, 2001
`
`(54) SYSTEM, METHOD, AND SENSORS FOR
`SENSING PHYSICAL PROPERTIES
`(75) Inventors: Mark G. Allen, Atlanta; Jennifer M.
`English, Kennesaw, both of GA (US)
`
`(73) Assignee: Georgia Tech Research Corporation,
`Atlanta, GA (US)
`0
`-
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`(*) Notice:
`
`(21) Appl. No.: 09/454,748
`(22) Filed:
`Dec. 6, 1999
`Related U.S. Application Data
`(63) Continuation-in-part of application No. 09/054.011, filed on
`Apr. 2, 1998, now Pat. No. 6,111,520.
`(51) Int. Cl." ................................................. G08B 21/00
`(52) U.S. Cl. ................................ 340/870.16; 340/870.17;
`340/870.31; 340/870.28; 340/447; 340/449;
`340/451; 340/584; 340/665; 340/521; 340/10.1;
`374/120; 374/183; 374/184; 422/82.02;
`331/66; 324/655; 73/774
`(58) Field of Search ......................... 340/870.16, 870.17,
`340/870.31, 647, 442, 449, 451, 584, 665,
`521,531, 10.1, 870.28; 374/120, 183, 184;
`422/82.02; 331/66; 324/655; 73/774
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`3,338,100 * 8/1967 Takami ................................. 374/154
`3,656,132 * 4/1972 Brumbelow
`... 340/870.28
`4,127,110 * 11/1978 Bullara ...........
`... 600/561
`4,203,128 * 5/1980 Guckel et al. .
`... 331/156
`4,237,900 * 12/1980 Schulman et al. .
`... 600/301
`4,455,874
`6/1984 Paros ...................................... 73/704
`4,494411
`1/1985 Koschke et al. ....................... 73/724
`4,660,568
`4/1987 Cosman ............................... 600/S61
`
`
`
`24 - -2
`
`allaKa C al. . . . . . . . . . . . . . . . . . . . . . . .
`
`5/1988 Stewart .................................. 73/505
`4,744,248
`4,764,244 * 8/1988 Chitty et al. ........................... 216/20
`4991283 * 2/1991 Johnson et al.
`... 29/595
`SE : i.1. R et al...
`3.
`5,312,674 * 5/1994 Haertling et al. .................... 428/210
`5,466,614 * 11/1995 Yakura et al. ......................... 438/14
`5,514,337 * 5/1996 E. N. - - - - - - -
`... 422/82.08
`5,514,832 * 5/1996 Dusablon, Sr. et al............. 174/15.1
`5,544,399
`8/1996 Bishop et al. .......
`... 92/25.41
`5,576,224 * 11/1996 Yakura et al. ....................... 438/381
`5,610,340 * 3/1997 Carr et al. ........
`... 73/718
`5,731,754 * 3/1998 Lee, Jr. et al.
`340/447
`5,770,803
`6/1998 Saito ...................................... 73/777
`* cited by examiner
`Primary Examiner Benjamin C. Lee
`(74) Attorney, Agent, or Firm Thomas, Kayden,
`Horstemeyer & Risley, L.L.P.
`(57)
`ABSTRACT
`Several Sensors are provided for determining one of a
`number of physical roperties including pressure,
`temperature, chemical Species, and other physical condi
`tions. In general, the Sensors feature a resonant circuit with
`an inductor coil which is electromagnetically coupled to a
`transmitting antenna. When an excitation Signal is applied to
`the antenna, a current is induced in the Sensor circuit. This
`current oscillates at the resonant frequency of the Sensor
`circuit. The resonant frequency and bandwidth of the Sensor
`circuit is determined using an impedance analyzer, a trans
`mitting and receiving antenna System, or a chirp interroga
`tion System. The resonant frequency may further be deter
`mined using a simple analog circuit with a transmitter. The
`Sensors are constructed So that either the resonant frequency
`or bandwidth of the sensor circuit, or both, are made to
`depend upon the physical properties Such as pressure,
`temperature, presence of a chemical Species, or other con
`dition of a specific environment. The physical properties are
`calculated from the resonant frequency and bandwidth deter
`mined.
`
`64 Claims, 33 Drawing Sheets
`
`Abbott
`Exhibit 1009
`Page 001
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`

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`U.S. Patent
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`Aug. 21, 2001
`
`Sheet 1 of 33
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`
`
`116
`
`112
`
`/
`
`\
`
`132
`128
`
`A
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`\71
`
`W
`
`Y
`
`1 28
`114
`128
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`108
`
`/\
`
`134
`
`o/ 102
`
`Fig. 1
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`Abbott
`Exhibit 1009
`Page 002
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`

`

`U.S. Patent
`
`Aug. 21, 2001
`
`Sheet 2 of 33
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`US 6,278.379 B1
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`
`
`-
`
`W.
`136 ---s
`
`104
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`135
`
`P
`
`Fig. 2
`
`Abbott
`Exhibit 1009
`Page 003
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`

`

`U.S. Patent
`
`Aug. 21, 2001
`
`Sheet 3 of 33
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`US 6,278.379 B1
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`
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`166
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`/ St.
`
`162 4. 154
`
`168
`
`Fig. 3
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`Abbott
`Exhibit 1009
`Page 004
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`

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`U.S. Patent
`
`Aug. 21, 2001
`
`Sheet 4 of 33
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`US 6,278.379 B1
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`
`
`Fig. 4
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`Abbott
`Exhibit 1009
`Page 005
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`

`

`U.S. Patent
`
`Aug. 21, 2001
`
`Sheet 5 of 33
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`US 6,278.379 B1
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`
`
`
`
`
`
`
`
`223
`
`200 /
`2's.
`
`208
`
`
`
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`
`212
`
`214
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`218
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`----es
`- rt
`--
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`A.
`
`-
`
`-----------
`
`Fig. 5
`
`Abbott
`Exhibit 1009
`Page 006
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`

`

`U.S. Patent
`
`Aug. 21, 2001
`
`Sheet 6 of 33
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`US 6,278.379 B1
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`2 -o-
`
`Hill?.
`
`214
`
`
`
`
`
`Fig. 6
`
`Abbott
`Exhibit 1009
`Page 007
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`

`

`U.S. Patent
`
`Aug. 21, 2001
`
`Sheet 7 of 33
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`US 6,278.379 B1
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`
`
`ZZ ).
`
`Z ‘61-I
`
`m.
`
`No. -
`D/
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`Abbott
`Exhibit 1009
`Page 008
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`

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`U.S. Patent
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`Aug. 21, 2001
`
`Sheet 8 of 33
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`US 6,278.379 B1
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`212
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`/ 400
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`208
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`Abbott
`Exhibit 1009
`Page 009
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`

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`U.S. Patent
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`Aug. 21, 2001
`
`Sheet 9 of 33
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`US 6,278.379 B1
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`
`
`
`
`Fig. 8B
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`Abbott
`Exhibit 1009
`Page 010
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`

`

`U.S. Patent
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`Aug. 21, 2001
`
`Sheet 10 of 33
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`
`
`Fig. 9
`
`Abbott
`Exhibit 1009
`Page 011
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`

`

`U.S. Patent
`
`Aug. 21, 2001
`
`Sheet 11 of 33
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`US 6,278.379 B1
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`
`
`
`
`
`
`X
`602 n
`X X X
`X X X X
`X X X X X
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`600
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`604
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`606
`
`impedance
`Analyzer
`612
`
`
`
`interface
`MOcule
`
`
`
`
`
`
`
`
`
`
`
`
`
`Computer Memory
`624
`
`Operating Logic
`626
`
`Abbott
`Exhibit 1009
`Page 012
`
`

`

`U.S. Patent
`
`Aug. 21, 2001
`
`Sheet 12 of 33
`
`US 6,278.379 B1
`
`
`
`O)
`
`CDo
`Frequency
`
`O)2
`
`Fig.11
`
`Abbott
`Exhibit 1009
`Page 013
`
`

`

`U.S. Patent
`
`Aug. 21, 2001
`
`Sheet 13 of 33
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`US 6,278.379 B1
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`
`
`Set Frequency Range
`632
`
`626
`
`Scan impedance ACross
`Range
`634
`
`Determine Resonant
`Frequency of Sensor
`636
`
`Determine Bandwidth of
`the Resonant Circuit
`638
`
`Calculate Physical
`Properties
`642
`
`Fig. 12
`
`Abbott
`Exhibit 1009
`Page 014
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`

`

`U.S. Patent
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`Aug. 21, 2001
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`Sheet 14 of 33
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`US 6,278.379 B1
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`602
`
`652
`
`604
`
`
`
`
`
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`608
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`X
`
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`Module
`656
`
`614
`
`Computer Memory
`624
`Operating Logic
`658
`
`Abbott
`Exhibit 1009
`Page 015
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`

`

`U.S. Patent
`
`Aug. 21, 2001
`
`Sheet 15 of 33
`
`US 6,278.379 B1
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`606
`
`Fig.14A
`
`654
`
`CDo
`Fig. 14B
`
`Abbott
`Exhibit 1009
`Page 016
`
`

`

`U.S. Patent
`
`Aug. 21, 2001
`
`Sheet 16 of 33
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`US 6,278.379 B1
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`
`
`658
`
`/
`
`Transmit/Receive
`Excitation Signal
`672
`
`Determine Resonant
`Frequency
`674
`
`Determine Bandwidth
`674
`
`Determine Physical
`Parameters
`676
`
`Fig. 15
`
`Abbott
`Exhibit 1009
`Page 017
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`

`

`U.S. Patent
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`Aug. 21, 2001
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`Sheet 17 of 33
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`US 6,278.379 B1
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`700
`
`702
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`604
`
`X X X X X X X X X
`X X X X X X X X X X X
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`
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`
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`Interface
`Module
`656
`
`Abbott
`Exhibit 1009
`Page 018
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`

`

`U.S. Patent
`
`Aug. 21, 2001
`
`Sheet 18 of 33
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`US 6,278.379 B1
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`606
`
`Time
`
`Fig.17A
`
`
`
`Abbott
`Exhibit 1009
`Page 019
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`

`

`U.S. Patent
`
`Aug. 21, 2001
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`Sheet 19 of 33
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`US 6,278.379 B1
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`750
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`
`62-N
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`
`
`
`Fig. 18
`
`758
`
`Abbott
`Exhibit 1009
`Page 020
`
`

`

`U.S. Patent
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`Aug. 21, 2001
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`Sheet 20 of 33
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`US 6,278.379 B1
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`/
`
`602
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`608b.
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`
`Impedance
`Analyzer
`612
`
`
`
`Interface
`Module
`
`
`
`
`
`
`
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`
`Computer Memory
`624
`
`Operating Logic
`626
`
`Abbott
`Exhibit 1009
`Page 021
`
`

`

`U.S. Patent
`
`Aug. 21, 2001
`
`Sheet 21 of 33
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`US 6,278.379 B1
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`
`
`Frequency :
`
`Fig. 20
`
`Abbott
`Exhibit 1009
`Page 022
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`

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`U.S. Patent
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`Aug. 21, 2001
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`Sheet 22 of 33
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`US 6,278.379 B1
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`8OO
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`
`Fig. 21A
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`Fig. 21B
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`Abbott
`Exhibit 1009
`Page 023
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`U.S. Patent
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`Aug. 21, 2001
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`Sheet 23 of 33
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`US 6,278.379 B1
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`2 2 Éf % % 2 % % % %
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`Abbott
`Exhibit 1009
`Page 024
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`

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`U.S. Patent
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`Aug. 21, 2001
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`Sheet 24 of 33
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`US 6,278.379 B1
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`853
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`856
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`
`Abbott
`Exhibit 1009
`Page 025
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`

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`U.S. Patent
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`Aug. 21, 2001
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`Sheet 25 of 33
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`US 6,278.379 B1
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`
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`Fig. 23
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`Abbott
`Exhibit 1009
`Page 026
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`U.S. Patent
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`Aug. 21, 2001
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`Sheet 26 of 33
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`US 6,278.379 B1
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`Abbott
`Exhibit 1009
`Page 027
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`U.S. Patent
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`Aug. 21, 2001
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`Sheet 27 of 33
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`US 6,278.379 B1
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`Exhibit 1009
`Page 028
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`U.S. Patent
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`Aug. 21, 2001
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`Sheet 28 of 33
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`US 6,278.379 B1
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`Exhibit 1009
`Page 029
`
`

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`U.S. Patent
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`Aug. 21, 2001
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`Sheet 29 of 33
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`US 6,278.379 B1
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`Fig. 27A
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`Abbott
`Exhibit 1009
`Page 030
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`U.S. Patent
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`Aug. 21, 2001
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`Sheet 30 of 33
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`US 6,278.379 B1
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`Page 031
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`U.S. Patent
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`Aug. 21, 2001
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`Sheet 31 of 33
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`US 6,278.379 B1
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`Exhibit 1009
`Page 032
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`U.S. Patent
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`Aug. 21, 2001
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`Sheet 32 of 33
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`US 6,278.379 B1
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`Abbott
`Exhibit 1009
`Page 033
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`U.S. Patent
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`Aug. 21, 2001
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`Sheet 33 of 33
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`US 6,278.379 B1
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`Exhibit 1009
`Page 034
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`

`

`1
`SYSTEM, METHOD, AND SENSORS FOR
`SENSING PHYSICAL PROPERTIES
`
`CROSS REFERENCE TO RELATED
`APPLICATIONS
`This application is a continuation-in-part of U.S. patent
`application entitled, “System, Method, and Sensors for
`Sensing Physical Properties,” filed on Apr. 2, 1998, accorded
`Ser. No. 09/054,011, now U.S. Pat. No. 6,111,520, and
`incorporated herein by reference.
`
`FIELD OF THE INVENTION
`This invention relates to the field of physical Sensors, and,
`more particularly, to Sensors for wirelessly Sensing pressure,
`temperature and other physical properties in a specific
`environment.
`
`15
`
`BACKGROUND OF THE INVENTION
`Sensing technology is currently employed in a number of
`different environments. Specifically, Sensors employed to
`determine the pressure or temperature of a medium are used
`in a wide variety of applications. Most Such applications
`involve the use of temperature and pressure Sensors in
`environments of low temperature or in environments of high
`temperature which require adequate cooling measures or the
`use of high temperature materials in the construction of Such
`Sensors. In Such applications, for example, micro-machining
`techniques exist by which pressure Sensors are constructed
`using Silicon as a Substrate.
`An example of a micromachined Silicon preSSure Sensor
`design is a capacitive pressure Sensor. This Sensor uses a
`parallel plate capacitor and a flexible Silicon diaphragm.
`Two Silicon wafers are bulk machined to create cavities in
`the silicon. One silicon wafer is bulk micromachined to
`create a deep cavity and Subsequently a thin membrane.
`Metal layers are deposited onto appropriate boundaries of
`the cavities creating the conductors of the parallel plate
`capacitor. The wafers are bonded So that the metal conduc
`tors are facing each other and a capacitor is formed. The
`capacitor is electrically connected to a Silicon circuit on the
`Substrate that in turn is connected to external electronic
`devices via wire leads. AS pressure of the medium in which
`the Sensor is placed increases, the diaphragm deflects and the
`distance between the plates of the capacitor decreases,
`causing an increase in the capacitance. The Silicon circuit
`reads the change in capacitance, and a resultant Voltage is
`output via the wire leads.
`Micromachined Sensors Such as the example given above
`Suffer problems when exposed to certain environmental
`conditions. In high temperature applications, the Silicon
`Sensor and Similar Sensors do not operate reliably or cease to
`function completely due to the heat. For example, Silicon
`begins to plastically deform at approximately 800° C. and
`melts at approximately 1400°C. The pressure readout due to
`the deflection of the flexible Silicon diaphragm is compro
`mised by the plastic deformation of Silicon causing perma
`nent measurement error. Many other Sensor materials have
`even lower melting points that limit the operating tempera
`ture of the environment. In addition, different environments
`may include corrosive elements in which Silicon or other
`Similar materials may not Survive.
`Another problem with micromachined Silicon Sensors and
`Similar Sensor technology is that circuitry, electrical
`connections, and wire leads through which temperature,
`preSSure, or other physical information is obtained can not
`
`25
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`35
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`40
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`45
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`50
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`55
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`US 6,278.379 B1
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`2
`withstand high temperature applications or corrosive envi
`ronments. For example, Silicon circuitry does not function at
`temperatures greater than 300 C. and high temperature
`Solders, conductive adhesives, and wiring Schemes are dif
`ficult to implement.
`In addition, in the case where a temperature, pressure, or
`other physical reading of an environment is measured from
`a Sensor mounted to a mobile Structure Such as a turbine
`blade or other moveable apparatus, chamber or vessel, the
`wire leads connected to traditional Sensors may interfere
`with the operation of the particular mobile structure. Such
`would also be the case of mobile vessels in which interior
`preSSure Sensing is desired.
`
`SUMMARY OF THE INVENTION
`In accordance with a first embodiment of the present
`invention, there is provided a Sensor for determining the
`preSSure of a specific environment. The preSSure Sensor
`features an inductive-capacitive (LC) resonant circuit with a
`variable capacitor. The capacitance varies with the preSSure
`of the environment in which the capacitor is placed.
`Consequently, the resonant frequency of the LC circuit of
`the pressure Sensor varies depending on the pressure of the
`environment. The pressure Sensor is made of completely
`passive components having no active circuitry or power
`Sources Such as batteries. The pressure Sensor is completely
`Self-contained having no leads to connect to an external
`circuit or power Source.
`In accordance with a Second embodiment of the present
`invention, there is provided a Sensor for determining the
`temperature of a specific environment. The temperature
`sensor features an inductive-capacitive (LC) resonant circuit
`with a variable capacitor. The capacitance varies with the
`temperature of the environment in which the capacitor is
`placed, the capacitor having a dielectric with a permittivity
`that varies with varying temperature. Consequently, the
`resonant frequency of the LC circuit of the pressure Sensor
`varies depending on the temperature of the environment.
`The temperature Sensor is made of completely passive
`components having no active circuitry or power Sources
`Such as batteries. Also, the temperature Sensor is completely
`Self-contained having no leads to connect to an external
`circuit or power Source.
`In accordance with a third embodiment of the present
`invention, there is provided a combination preSSure and
`temperature Sensor for determining both the pressure and
`temperature of a specific environment. The combination
`Sensor features a first inductive- capacitive (LC) resonant
`circuit Similar to that of the first embodiment, and a Second
`LC circuit similar to that of the second embodiment. The
`temperature Sensing portion of the combination Sensor pro
`vides an independent Source of temperature information that
`may be employed in real time calibration of the preSSure
`Sensor. The combination Sensor is also constructed of com
`pletely passive components having no active circuitry or
`power Sources Such as batteries. Also, the combination
`Sensor is completely Self-contained having no leads to
`connect to an external circuit or power Source.
`In accordance with a fourth embodiment of the present
`invention, there is provided a Sensor having a resistance that
`is variable with a specific property or physical condition of
`a specific environment. The variable resistance Sensor fea
`tures a resistive-inductive-capacitive (RLC) resonant circuit
`with a variable resistance. The resistance may vary with the
`temperature, chemical makeup of the environment including
`chemical Species, or other physical condition of the envi
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`Abbott
`Exhibit 1009
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`3
`ronment to which the variable resistance is exposed.
`Consequently, the bandwidth of the RLC circuit of the
`variable resistance Sensor varies depending on the value of
`the variable resistance which depends on a specific physical
`condition of the environment. The variable resistance Sensor
`is made of completely passive components having no active
`circuitry or power Sources Such as batteries and is com
`pletely Self-contained having no leads to an external circuit
`or power Source.
`In accordance with a fifth embodiment of the present
`invention, there is provided a variable resistance and pres
`Sure Sensor that is a combination of the first and fourth
`embodiments. In the fifth embodiment, the inclusion of a
`variable resistance in the LC circuit of the first embodiment
`allows the determination of both the pressure from the
`resonant frequency of the resulting RLC circuit due to the
`variable capacitance, and the temperature or other physical
`condition from the bandwidth of the RLC circuit due to the
`variable resistance.
`The Sensors of the present invention are used in conjunc
`tion with Several different excitation Systems, resulting in a
`System and method for determining the pressure,
`temperature, or other physical condition. Accordingly, each
`of the above described Sensors is electromagnetically
`coupled to a transmitting antenna. Consequently, a current is
`induced in each of the Sensors that oscillates at the resonant
`frequency of the Sensor in question. This oscillation causes
`a change in the frequency Spectrum of the transmitted Signal.
`From this change, the bandwidth and resonant frequency of
`the particular Sensor may be determined, from which the
`corresponding physical parameters are calculated.
`Accordingly, the present invention provides for an imped
`ance System and method of determining the resonant fre
`quency and bandwidth of a resonant circuit within a par
`ticular Sensor. The System includes a transmitting antenna
`that is coupled to an impedance analyzer. The impedance
`analyzer applies a constant amplitude Voltage Signal to the
`transmitting antenna Scanning the frequency acroSS a pre
`determined spectrum. The current passing through the trans
`mitting antenna experiences a peak at the resonant frequency
`of the Sensor. The resonant frequency and bandwidth are
`thus determined from this peak in the current.
`The method of determining the resonant frequency and
`bandwidth using an impedance approach may include the
`Steps of transmitting an excitation Signal using a transmitting
`antenna and electromagnetically coupling a Sensor having a
`resonant circuit to the transmitting antenna thereby modi
`fying the impedance of the transmitting antenna. Next, the
`Step of measuring the change in impedance of the transmit
`ting antenna is performed, and finally, the resonant fre
`quency and bandwidth of the Sensor circuit are determined.
`In addition, the present invention provides for a transmit
`and receive System and method for determining the resonant
`frequency and bandwidth of a resonant circuit within a
`particular Sensor. According to this method, an excitation
`Signal of white noise or predetermined multiple frequencies
`is transmitted from a transmitting antenna, the Sensor being
`electromagnetically coupled to the transmitting antenna. A
`current is induced in the resonant circuit of the Sensor as it
`absorbs energy from the transmitted excitation signal, the
`current oscillating at the resonant frequency of the resonant
`circuit. A receiving antenna, also electromagnetically
`coupled to the transmitting antenna, receives the excitation
`Signal minus the energy that was absorbed by the Sensor.
`Thus, the power of the received Signal experiences a dip or
`notch at the resonant frequency of the Sensor. The resonant
`frequency and bandwidth are determined from this notch in
`the power.
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`The transmit and receive method of determining the
`resonant frequency and bandwidth of a Sensor circuit
`includes the Steps of transmitting a multiple frequency Signal
`from transmitting antenna, and, electromagnetically cou
`pling a resonant circuit on a Sensor to the transmitting
`antenna thereby inducing a current in the Sensor circuit.
`Next, the Step of receiving a modified transmitted Signal due
`to the induction of current in the Sensor circuit is performed.
`Finally, the Step of determining the resonant frequency and
`bandwidth from the received Signal is executed.
`Yet another System and method for determining the reso
`nant frequency and bandwidth of a resonant circuit within a
`particular Sensor includes a chirp interrogation System. This
`System provides for a transmitting antenna that is electro
`magnetically coupled to the resonant circuit of the Sensor.
`An excitation signal of white noise or predetermined mul
`tiple frequencies is applied to the transmitting antenna for a
`predetermined period of time, thereby inducing a current in
`the resonant circuit of the Sensor at the resonant frequency.
`The System then listens for a return signal that radiates from
`the sensor. The resonant frequency and bandwidth of the
`resonant circuit are determined from the return signal.
`The chirp interrogation method for determining the reso
`nant frequency and bandwidth of a resonant circuit within a
`particular Sensor includes the Steps of transmitting a multi
`frequency Signal pulse from a transmitting antenna, electro
`magnetically coupling a resonant circuit on a Sensor to the
`transmitting antenna thereby inducing a current in the Sensor
`circuit, listening for and receiving a return signal radiated
`from the Sensor circuit, and determining the resonant fre
`quency and bandwidth from the return Signal.
`Finally, the present invention provides an analog system
`and method for determining the resonant frequency of a
`resonant circuit within a particular Sensor. The analog sys
`tem comprises a transmitting antenna coupled as part of a
`tank circuit that in turn is coupled to an oscillator. A signal
`is generated which OScillates at a frequency determined by
`the electrical characteristics of the tank circuit. The fre
`quency of this signal is further modified by the electromag
`netic coupling of the resonant circuit of a Sensor. This signal
`is applied to a frequency discriminator that in turn provides
`a signal from which the resonant frequency of the Sensor
`circuit is determined.
`The analog method for determining the resonant fre
`quency and bandwidth of a resonant circuit within a par
`ticular Sensor includes the Steps of generating a transmission
`Signal using a tank circuit which includes a transmitting
`antenna, modifying the frequency of the transmission signal
`by electromagnetically coupling the resonant circuit of a
`Sensor to the transmitting antenna, and converting the modi
`fied transmission Signal into a Standard Signal for further
`application.
`In another embodiment, the present invention provides for
`a pressure Sensor, comprising a resonant circuit having a
`capacitor and an inductor. The pressure Sensor further
`includes a Substrate with a structural layer placed over the
`Substrate, the Structural layer defining a cavity with a dia
`phragm having an external Surface and an internal Surface,
`the diaphragm being moveable in response to a preSSure
`applied to the external Surface. Also, the capacitor is com
`prised of at least a first plate positioned on the diaphragm
`and a Second plate positioned opposite the first plate with the
`cavity therebetween, wherein a capacitance of the capacitor
`is variable with a movement of the diaphragm. Finally, the
`inductor includes a first end coupled to the first plate and a
`Second end coupled to the Second plate, the inductor induc
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`Abbott
`Exhibit 1009
`Page 036
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`S
`ing a current in the resonant circuit when exposed to a
`time-varying electromagnetic field.
`In another embodiment, a temperature Sensor is provided,
`comprising a resonant circuit having a capacitor and an
`inductor. The temperature Sensor also includes a Substrate, a
`first plate located on the Substrate, and a structural layer
`placed over the Substrate, the Structural layer covering the
`first plate and the Structural layer having a permittivity that
`changes with temperature. The temperature Sensor also
`includes a Second plate placed over the Structural layer
`opposite the first plate, the first and Second plates forming
`the capacitor and the inductor having a first end coupled to
`the first plate and a Second end coupled to the Second plate,
`the inductor inducing a current in the resonant circuit when
`exposed to a time-varying electromagnetic field.
`In Still another embodiment, a temperature Sensor is
`provided, comprising a resonant circuit having a capacitor,
`an inductor, and a resistor. The temperature Sensor also
`comprises a Substrate, a first plate located on the Substrate,
`and a structural layer placed over the Substrate, the Structural
`layer covering the first plate, and the Structural layer having
`a permittivity that changes with temperature. The tempera
`ture Sensor further includes a Second plate placed over the
`Structural layer and adjacent to the first plate, the first and
`Second plates forming the capacitor. Finally, the temperature
`Sensor comprises the resistor being variable in response to a
`change in temperature, and the inductor inducing a current
`in the resonant circuit when exposed to a time-varying
`electromagnetic field.
`The present invention also includes an embodiment
`directed to a Sensor to detect a presence of a chemical
`Species in a medium, comprising a resonant circuit having a
`capacitor, an inductor, and a resistor. The chemical Species
`Sensor also includes a Substrate, a first plate located on the
`Substrate, a structural layer placed over the Substrate, the
`Structural layer covering the first plate, the Structural layer
`having a permittivity that changes with temperature, and a
`Second plate placed over the Structural layer and adjacent to
`the first plate, the first and Second plates forming the
`capacitor. The chemical Species Sensor also includes the
`resistor being variable in response to a presence of a
`chemical Species, and the inductor inducing a current in the
`resonant circuit when exposed to a time-varying electro
`magnetic field.
`In another embodiment, the present invention provides for
`an acceleration Sensor, comprising a resonant circuit having
`a capacitor and an inductor. The acceleration Sensor also
`includes a Substrate, a Structural layer placed over the
`Substrate, the Structural layer defining a cavity with a dia
`phragm having an external Surface and an internal Surface,
`the diaphragm being moveable in response to an accelera
`tion experienced by the acceleration Sensor. The capacitor of
`the acceleration Sensor at least a first plate positioned on the
`diaphragm and a Second plate positioned opposite the first
`plate with the cavity therebetween, wherein a capacitance of
`the capacitor is variable with a movement of the diaphragm,
`and the inductor having a first end coupled to the first plate
`and a Second end coupled to the Second plate, the inductor
`inducing a current in the resonant circuit when exposed to a
`time-varying electromagnetic field.
`Finally, in another embodiment, a Second acceleration
`Sensor is provided, comprising a resonant circuit having a
`capacitor and an inductor. The Second acceleration Sensor
`includes a first layer having a first plate, at least one middle
`layer having a hole, and a Second layer having a Second
`plate, wherein the first layer, middle layer, and the Second
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`layer are Stacked, the first plate being located opposite the
`second plate with the hole therebetween. The first and
`Second plates of the Second acceleration Sensor define the
`capacitor, the first plate defining a diaphragm that is move
`able in response to an acceleration experienced by the
`acceleration Sensor, the first capacitor having a capacitance
`that varies with a movement of the diaphragm, the inductor
`inducing a current in the resonant circuit when exposed to a
`time-varying electromagnetic field.
`According to the present invention, multiple Sensors may
`be employed at a Single time to provide redundancy and
`more accurate information, or to measure Several physical
`conditions simultaneously. Also, the Spatial resolution of
`physical characteristics may be obtained. Such multiple
`Sensors may either be discretely placed in the System to be
`Sensed, or may all be formed on or in a Single Substrate
`according to batch fabrication techniques and placed in the
`System or environment to be Sensed.
`The above mentioned Sensors may be advantageously
`manufactured using a bulk machining approach, a Surface
`machining approach, or a combination of bulk machining
`and Surface machining.
`Other features and advantages of the present invention
`will become apparent to one with skill in the art upon
`examination of the following drawings and detailed descrip
`tion. It is intended that all Such additional features and
`advantages be included herein within the Scope of the
`present invention, as defined by the claims.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The invention can be better understood with reference to
`the following drawings. The components in the drawings are
`not necessarily to Scale, emphasis instead being placed upon
`clearly illustrating the principles of the present invention. In
`the drawings, like reference numerals designate correspond
`ing parts throughout the Several views.
`FIG. 1 is an assembly view of a preSSure Sensor according
`to a first embodiment of the present invention;
`FIG. 2 is a croSS-Sectional view of the pressure Sensor of
`FIG. 1;
`FIG. 3 is an assembly view of an alternative pressure
`Sensor according to the first embodiment of the present
`invention;
`FIG. 4 is a croSS-Sectional view of the pressure Sensor of
`FIG. 3;
`FIG. 5 is an assembly view of a temperature sensor
`according to a Second embodiment of the present invention;
`FIG. 6 is a cross-sectional view of the pressure sensor of
`FIG. 5;
`FIG. 7 is a cross-sectional view of a dual pressure and
`temperature Sensor according to a third embodiment of the
`present invention;
`FIG. 8A is an assembly view of a temperature sensor
`according to a fourth embodiment of the present invention;
`FIG. 8B is a graphical plot of the bandwidth of a resonant
`circuit of the temperature sensor or FIG. 8A:
`FIG. 9 is an assembly view of a dual pressure and
`temperature Sensor according to a fifth embodiment of the
`present invention;
`FIG. 10 is a block diagram of an excitation system that
`measures the impedance of the Sensor;
`FIG. 11 is a graphical plot of the current through the
`transmitting antenna as determined by the excitation System
`of FIG. 10;
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`Abbott
`Exhibit 1009
`Page 037
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`FIG. 12 is a flow diagram of the op