Long-Term Performance of Ultrasonic Transducers Used for Energy and Data Transmission

In this work, we present experimental results on the long-term performance of ultrasonic transducers elements. For aeronautic applications these devices are targeted for the wireless transmission of energy and data to and from sensor elements placed inside of hermetically sealed metal envelopes, typically used e.g. for hydraulic accumulators, oxygen bottles, fuel tanks etc. By exciting the transmitter piezo in resonance, acoustic waves are generated traveling through the metallic body and are reconverted to electrical energy on the receiving side. Commercially available cylindrically shaped piezoelectric elements have been selected in order to build up an energy and data transmission system. In a test arrangement for preevaluation purposes both piezoelectric elements are arranged on opposite sides of a metal wall, fixed by using an electrically conductive epoxy and exposed to ambient temperatures up to of 100 deg C. Furthermore, a concept is presented how to integrate the complete system in a compact way in a hydraulic accumulator.