Wireless and passive acoustic wave liquid conductivity sensor

• US 20060254356A1
• Filed: 05/11/2005
• Published: 11/16/2006
• Est. Priority Date: 05/11/2005
• Status: Abandoned Application

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Rhodes, Michael L., Rahman, Aziz, Liu, James ZT
• Application Number:
  US11/127,635
• Publication Number:
  US 20060254356A1
• Time in Patent Office: Days
• US Class Current: 73/592
• CPC Class Codes: G01N 2291/011 Velocity or travel time
• CPC Class Codes: G01N 2291/014 Resonance or resonant frequency
• CPC Class Codes: G01N 2291/0256 Adsorption, desorption, surface mass change, e.g. on biosensors
• CPC Class Codes: G01N 2291/02863 Electric or magnetic parameters
• CPC Class Codes: G01N 2291/0422 Shear waves, transverse waves, horizontally polarised waves
• CPC Class Codes: G01N 2291/0423 Surface waves, e.g. Rayleigh waves, Love waves
• CPC Class Codes: G01N 2291/0427 Flexural waves, plate waves, e.g. Lamb waves, tuning fork, cantilever
• CPC Class Codes: G01N 2291/105 two or more emitters, two or more receivers
• CPC Class Codes: G01N 29/022 Fluid sensors based on microsensors, e.g. quartz crystal-microbalance [QCM], surface acoustic wave [SAW] devices, tuning forks, cantilevers, flexural plate wave [FPW] devices microdevices per se B81B
• CPC Class Codes: G01N 29/2462 Probes with waveguides, e.g. SAW devices
• CPC Class Codes: G01N 29/2481 Wireless probes, e.g. with transponders or radio links
• CPC Class Codes: G01S 13/755 using delay lines, e.g. acoustic delay lines

Abstract

A method and system for measuring liquid conductivity utilizing an acoustic wave sensor. In general, an acoustic wave device can be provided with one or more interdigital transducers, including at least a first interdigital transducer and at least a second interdigital transducer having a cavity formed therebetween, wherein liquid comes into contact with the cavity. For example, a liquid, such as oil, may flow through the cavity. A measurement of the resistance and/or frequency of the acoustic wave device next to the cavity can be performed in order to obtain data indicative of the conductivity of the liquid.

Claims

1. A method for measuring liquid conductivity utilizing an acoustic wave sensor, comprising:

providing an acoustic wave device having a first interdigital transducer and a second interdigital transducer having a gap formed therein, wherein a liquid contacts said gap; and

measuring a resistance of said gap in order to obtain data indicative of a conductivity of said liquid.

2. The method of claim 1 wherein said acoustic wave device comprises a bulk acoustic wave (BAW) device that generates at least one bulk acoustic wave that assists in providing a measurement of said conductivity of said liquid.

3. The method of claim 1 wherein said acoustic wave device comprises an SH-SAW device that generates at least one shear-horizontal surface acoustic wave that assists in providing a measurement of said conductivity of said liquid.

4. The method of claim 1 wherein said acoustic wave device comprises an FPW device that generates at least one flexural plate wave that assists in providing a measurement of said conductivity of said liquid.

5. The method of claim 1 wherein said acoustic wave device comprises an SH-APM device that generates at least one shear horizontal surface acoustic wave that assists in providing a measurement of said conductivity of said liquid.

6. The method of claim 1 further comprising forming said first and second interdigital transducers to comprise a pattern of dual delay lines that assist in providing a measurement of said conductivity of said liquid.

7. A method for measuring liquid conductivity utilizing an acoustic wave sensor, comprising:

providing an acoustic wave device having a plurality of interdigital transducers formed thereon, wherein a cavity is configured from said acoustic wave device, wherein a liquid is flowable through the said cavity; and

measuring a frequency change of said acoustic wave device in order to obtain data indicative of a conductivity of said liquid flowing through said cavity.

8. The method of claim 7 wherein said acoustic wave device comprises an SH-SAW device that generates at least one shear-horizontal surface acoustic wave that assists in providing a measurement of said conductivity of said liquid.

9. The method of claim 7 wherein said acoustic wave device comprises an FPW device that generates at least one flexural plate wave that assists in providing a measurement of said conductivity of said liquid.

10. The method of claim 7 wherein said acoustic wave device comprises an APM device that generates at least one shear horizontal surface acoustic wave that assists in providing a measurement of said conductivity of said liquid.

11. The method of claim 7 further comprising forming said plurality of interdigital transducers comprise a pattern of dual delay lines that assist in providing a measurement of said conductivity of said liquid.

12. The method of claim 7 further comprising configuring said plurality of interdigital transducers to comprise a pattern of two-port resonators that assist in providing a measurement of said conductivity of said liquid.

13. The method of claim 7 wherein said acoustic wave device comprises a two-port SH-SAW resonator device that generates at least one shear-horizontal surface acoustic wave that assists in providing a measurement of said conductivity of said liquid.

14. The method of claim 7 wherein said acoustic wave device comprises a two-port FPW resonator device that generates at least one shear-horizontal surface acoustic wave that assists in providing a measurement of said conductivity of said liquid.

15. The method of claim 7 wherein said acoustic wave device comprises a two-port APM resonator device that generates at least one shear-horizontal surface acoustic wave that assists in providing a measurement of said conductivity of said liquid.

16. A wireless and passive liquid conductivity sensing system, comprising:

an acoustic wave device; and

a sensing mechanism that is connectable to said liquid, wherein said sensing mechanism comprises at least one acoustic wave sensing element formed from said acoustic wave device and at least one antenna associated with said acoustic wave device that communicates with said at least one acoustic wave sensing element, wherein when said at least one acoustic wave sensing element is in contact with said liquid, such that said at least one acoustic wave sensing element detects acoustic waves associated with said liquid in response to an excitation of said at least one acoustic wave sensing element, thereby generating data indicative of a conductivity of said liquid for wireless transmission through said at least one antenna.

17. The system of claim 16 wherein said excitation of said at least one acoustic wave sensing element occurs in response to at least one wireless signal transmitted to said at least one antenna.

18. The system of claim 17 wherein said acoustic waves associated with said liquid comprise at least one of the following types of acoustic waves:

bulk wave, acoustic plate mode, shear-horizontal acoustic plate mode, surface transverse wave, flexural plate wave and shear-horizontal surface acoustic waves.

19. The system of claim 17 wherein said at least one acoustic wave sensing element comprises a plurality of interdigital transducers configured in a pattern of dual delay lines that assist in providing a measurement of said conductivity of said liquid.

20. The system of claim 17 wherein said at least one acoustic wave sensing element comprises a plurality of interdigital transducers configured in a pattern of two-port resonators that assist in providing a measurement of said conductivity of said liquid.

21. The system of claim 17 wherein said acoustic wave device comprises at least one of the following types of acoustic wave devices:

a two-port SH-SAW resonator device that generates at least one shear-horizontal surface acoustic wave that assists in providing a measurement of said conductivity of said liquid;

a two-port FPW resonator device that generates at least one shear-horizontal surface acoustic wave that assists in providing a measurement of said conductivity of said liquid;

or

a two-port APM resonator device that generates at least one shear-horizontal surface acoustic wave that assists in providing a measurement of said conductivity of said liquid.

22. A wireless and passive liquid sensing system, comprising:

an acoustic wave device; and

a sensing mechanism that is connectable to a liquid, wherein said sensing mechanism comprises at least three acoustic wave sensing elements formed from said acoustic wave device and at least one antenna associated with said acoustic wave device that communicates with said at least three acoustic wave sensing element, wherein at least one sensing element of the said at least three acoustic wave sensing elements is configured offset from theat least two acoustic wave sensing elements among said at least three acoustic wave sensing elements, thereby creating different temperature coefficients of frequency among said at least three sensing elements, thereby allowing said acoustic wave device to obtain data indicative of temperature and other parameters associated with said liquid.

23. The sensor system of claim 22 wherein said other parameters include viscosity, conductivity, pH, lubricity, and corrosivity.