Wireless Telemetry for Characterization of Piezoelectric Energy Harvesters in Tires

In order to design electronic systems and circuits powered by mechanical energy harvesting in novel applications, it is essential to obtain information about electrical quantities related to the transducer like voltages, currents, and power in realistic operating conditions. However, in some cases, e.g. in tires, transducers and circuits are not accessible, and it is difficult to predict theoretically or numerically the exact values of the above mentioned quantities. To overcome this limitation, this paper presents the design of a wireless telemetry circuit capable of measuring and acquiring open-circuit voltage, short-circuit currents, and static power transfer characteristics from piezoelectric transducers. The circuit was tested in a commercial tire on a drum test machine at different speeds and axial loads. The characterization under these conditions of a commercial piezoelectric harvester suitable for use in tires is reported.