Piezoelectric multifrequency energy converter for power harvesting in autonomous microsystems

A multifrequency mechanoelectrical piezoelectric converter intended for powering autonomous sensors from background vibrations is presented. The converter is composed of multiple bimorph cantilevers with different natural frequencies, whose rectified outputs are fed to a single storage capacitor. The structure of the converter, description of the operation, and measurement data on the performances are reported. Experimental results show the possibility of using the converter with input vibrations across a wideband frequency spectrum, improving the effectiveness of the overall energy conversion over the case of a single converter. The converter was used to supply power to a battery-less sensor module that intermittently reads the signal from a passive sensor and sends the measurement information via RF transmission, in this way forming an autonomous sensor system with improved measure-and-transmit rate.