Self-powered acoustic sensor system

An acoustic sensor for sensing environmental attributes within an enclosure, the acoustic sensor comprising:

• a bulk acoustic wave (BAW) transducer configured to be installed outside the enclosure coupled to an outside wall of the enclosure, wherein the BAW transducer is further configured to generate an ultrasonic wave pulse and receive a reflected ultrasonic wave pulse;
• a waveguide assembly configured to be installed inside the enclosure, the waveguide assembly comprising:
• an acoustic horn, configured to be coupled at an enlarged end to an inside wall of the enclosure at a first interface of the waveguide assembly, and configured to receive the ultrasonic wave pulse generated by the BAW transducer;
• and
• a waveguide coupled to a reduced end of the acoustic horn at second interface of the waveguide assembly, wherein the waveguide includes a first waveguide portion coupled at a third interface to a second waveguide portion, wherein an uncoupled end of the second waveguide portion is adapted as a distal end of the waveguide, wherein the waveguide is configured to receive the ultrasonic wave pulse that is propagated from the BAW transducer through enclosure wall to the acoustic horn, and from the acoustic horn through solid portions of the waveguide;
• wherein the ultrasonic wave pulse is reflected from the second interface, the third interface, and the distal end, through the first interface and the enclosure wall to the BAW transducer, and wherein at least one physical property of the waveguide is sensitive to the environmental attributes within an enclosure.

A method of sensing environmental attributes within an enclosure, the method comprising:

• generating, by a bulk acoustic wave (BAW) transducer, an ultrasonic wave pulse, wherein the BAW transducer is installed on an outer surface of the enclosure, wherein the generated ultrasonic wave pulse is received by structured portions of a waveguide assembly installed isolated from the BAW transducer on an inner surface of the enclosure;
• providing a solid acoustic horn, configured to be installed on the inner surface of the enclosure at a first interface, and configured to receive the ultrasonic wave pulse generated by the BAW transducer;
• and
• providing a first waveguide portion coupled at second interface to the acoustic horn, wherein the first waveguide portion is coupled at a third interface to a first end of a second waveguide portion, wherein second end of the second waveguide portion is adapted as a distal end of the waveguide assembly, and
• reflecting the ultrasonic wave pulse through structural portions from the second interface, the third interface, and the distal end through back through the first interface, through the inner and outer surfaces of the enclosure, and to the BAW transducer;
• receiving, by the BAW transducer, the reflected ultrasonic wave pulse from the waveguide assembly;
• receiving, by a sensing device, a generated electric pulse corresponding to the generated ultrasonic wave pulse and a reflected electric pulse corresponding to the reflected ultrasonic wave pulse from the BAW transducer;
• comparing, by the sensing device, the generated electric pulse and the reflected electric pulse;
• determining, by the sensing device, a change in one or more wave propagation parameters based on the comparison;
• and
• determining, by the sensing device, one or more environmental attributes within the enclosure, based on the change in the one or more acoustic wave propagation parameters.

A self-powered acoustic sensor system for sensing an environmental attribute when a sensor installed inside an enclosure is isolated by a medium of the enclosure, comprising:

• a bulk acoustic wave (BAW) transducer configured to be installed on an outer surface of the enclosure;
• a solid acoustic horn isolated from the bulk acoustic wave transducer by the enclosure, configured to be installed on an inner surface of the enclosure at a first interface, and configured to receive an ultrasonic wave pulse generated by the BAW transducer;
• a first waveguide portion connected at a first end to the acoustic horn at a second interface;
• a second waveguide portion connected to the first waveguide portion at a third interface configured at a distal end of the waveguide assembly,
• wherein the self-powered acoustic sensor system is configured such that the ultrasonic wave pulse from the bulk acoustic wave transducer can be reflected by the second interface, the third interface, and the distal end and propagate back to the acoustic horn where the ultrasonic wave pulse is focused through the first interface and propagates through the inner enclosure surface and the outer enclosure surface back to the bulk wave transducer;
• and
• wherein the environmental attributes to be measured include temperature, pressure, relative humidity, and gas species.