Passive acoustic wave sensor system
First Claim
1. An acoustic wave sensor system comprising:
- an acoustic wave sensing device having a piezoelectric substrate, an antenna integrated in said sensing device, one or more transducers, coupled to said substrate and said antenna, said transducer(s) being adapted and arranged to transform an interrogation signal, received by said antenna, into an acoustic wave propagating in said device and to transform the propagated wave into a response for transmission by said antenna, and an interactive region having an electrically open surface arranged in a path of the wave such that a liquid disposed at or adjacent to said interactive region can interact acousto-electrically with said propagating wave, and whereby said sensing device, in reply to said interrogation signal, can transmit a response in which changes in frequency, phase or other propagation characteristics of said wave caused by said liquid acousto electric interaction can be analyzed to evaluate the conductivity, pH or other electrical properties of the liquid.
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Abstract
A passive acoustic wave sensor system for monitoring the quality of liquids, such as engine oil, is disclosed. The sensor system has an acoustic wave sensing device for generating a propagating acoustic wave and for detecting changes in frequency or other propagation characteristics of the acoustic wave caused by acousto-electric interactions between the liquid and the wave at an interactive region of the device. An antenna is integrated in the sensing device for receiving an interrogation signal and for transmitting the output response of the sensing device. The output response can be analyzed to determine the conductivity, pH or other electrical characteristics of the liquid. One or more reference devices may be utilized to compensate for mechanical effects of the liquid and temperature or other environmental effects. The sensing and reference devices can be configured as SH-SAW, SH-APM, FPM devices or other acoustic wave devices.
53 Citations
20 Claims
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1. An acoustic wave sensor system comprising:
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an acoustic wave sensing device having a piezoelectric substrate, an antenna integrated in said sensing device, one or more transducers, coupled to said substrate and said antenna, said transducer(s) being adapted and arranged to transform an interrogation signal, received by said antenna, into an acoustic wave propagating in said device and to transform the propagated wave into a response for transmission by said antenna, and an interactive region having an electrically open surface arranged in a path of the wave such that a liquid disposed at or adjacent to said interactive region can interact acousto-electrically with said propagating wave, and whereby said sensing device, in reply to said interrogation signal, can transmit a response in which changes in frequency, phase or other propagation characteristics of said wave caused by said liquid acousto electric interaction can be analyzed to evaluate the conductivity, pH or other electrical properties of the liquid. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An acoustic wave sensor system comprising:
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an acoustic wave sensing device having a piezoelectric substrate, an antenna integrated in said sensing device, one or more transducers, coupled to said substrate and said antenna, said transducer(s) being adapted and arranged to transform an interrogation signal, received by said antenna, into an acoustic sensing wave propagating in said device and to transform the propagated wave into a response for transmission by said antenna, and an interactive region having an electrically open surface arranged in a path of the wave such that a liquid disposed at or adjacent said interactive region can interact acousto-electrically and mechanically with said propagating sensing wave, said sensing device, in reply to said interrogation signal, transmitting a response including changes in frequency, phase or other propagation characteristics of said wave caused by said acoustic-electric interactions and said mechanical interactions, and at least one acoustic wave reference device, each reference device comprising;
one or more transducers, coupled to said substrate and said antenna, said transducer(s) being adapted and arranged to transform an interrogation signal, received by said antenna, into an acoustic reference wave propagating in said reference device and to transform the propagated reference wave into a response for transmission by said antenna, and a reference region arranged in a path of the wave such that a liquid disposed at or adjacent said reference region causes only mechanical interactions with said propagating reference wave, each reference device, in reply to said interrogation signal, transmitting a response including changes in frequency, phase or other propagation characteristics of said reference wave(s) caused by said mechanical interactions, and whereby, when said liquid is disposed at or adjacent both said interactive region and said reference region(s), said responses of said sensing device and said reference device(s) are mixable to isolate changes in said propagation characteristics caused by said acousto-electric interactions for analysis thereof to evaluate the conductivity, pH or other electrical properties of the liquid. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A method of remotely sensing the conductivity, pH or other electrical properties of a liquid comprising the steps of:
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generating an interrogation signal, transmitting said interrogation signal, receiving said interrogation signal, transforming said received interrogation signal into a propagating acoustic sensing wave, acousto-electrically interacting a liquid with said propagating sensing wave, transforming said propagating wave into a sensing response, transmitting said sensing response, measuring changes in the propagation characteristics of the sensing wave caused by said acousto-electric interactions, analyzing said changes in said propagation characteristics to evaluate the conductivity, pH or other electrical properties of the liquid.
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19. A method of claim 19, further comprising the steps of:
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mechanically interacting said liquid with said propagating sensing wave, transforming said received interrogation signal into a first propagating acoustic reference wave, mechanically interacting said liquid with said first propagating reference wave, transforming said propagating first reference wave into a first reference response, transmitting said first reference response, and mixing said sensing response and said reference response to isolate changes to said sensing wave propagation characteristics caused by said acousto electric interactions of said liquid. - View Dependent Claims (20)
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Specification