In many sensing applications that monitor extreme environmental conditions within sealed metallic vessels,
penetrating vessel walls in order to feed through power and data cables is impractical, as this may compromise a
vessels structural integrity and its environmental isolation. Frequent servicing of sensing equipment within these
environments is costly, so the use of batteries is strongly undesired and power harvesting techniques are preferred.
Traditional electromagnetic power delivery and communication techniques, however, are highly ineffective in
these applications, due to Faraday shielding effects from the metallic vessel walls. A viable, non-destructive
alternative is to use piezoelectric materials to transmit power through thick metallic barriers acoustically. We
present critical elements of a high-temperature battery-less sensor system prototype, including power harvesting,
voltage regulation, and data communication circuitry able to operate up to 260°C. Power transmission is achieved
by coaxially aligning a pair of high-temperature piezoelectric transducers on opposite sides of a thick steel barrier.
Continuous-wave excitation of the outside transducer creates an acoustic beam that is captured by the opposite
transducer, forming an acoustic-electric link for power harvesting circuitry. Simultaneously, sensor data can be
transmitted out of the high-temperature environment by switching the electrical impedance placed across the
leads of the inside transducer, creating a reflection-based amplitude modulated signal on the outside transducer.
Transducer housing, loading, and alternatives for acoustic couplants are discussed. Measurement results are
presented, and it was found that the system can harvest up to 1 watt of power and communicate sensor data up
to 50 kbps, while operating at 260°C.