Shock Reliability of Vacuum-Packaged Piezoelectric Vibration Harvester for Automotive Application

This paper reports for the first time the shock reliability of vacuum-packaged piezoelectric vibration harvesters for automotive application. Experimental study on >80 devices shows that the failure is induced by the impact between seismic mass and glass package. The statistical results obtained for various types of harvesters have shown a trend of higher shock reliability for a higher resonance frequency. The influence of beam thickness on the shock reliability is then discussed. The trade-off between the power output and shock reliability is elaborated. To further improve the reliability to the level of automotive application, the idea of stepped cavity is discussed and implemented. The experimental results confirmed a significantly enhanced reliability increased by ~50%, up to maximum 2000 g, for the same type of device under shock excitations.