Low-frequency wide-band hybrid energy harvester based on piezoelectric and triboelectric mechanism

Recently, hybrid energy harvester has been considered as an attractive potential approach to response the worldwide energy crisis due to the combination of advantages from different harvesting mechanism. In this paper, a novel low-frequency wide-band hybrid energy harvester based on piezoelectric and triboelectric mechanism is presented and systematically studied including structural design, fabrication process, working principle simulation and measurement. With a vibrational excitation, the polyvinylidene fluoride (PVDF) cantilevers will vibrate and impact the polydimethylsiloxane (PDMS) film on the substrate, producing a piezoelectric output as well as a triboelectric output. The structural parameters of each cantilever are optimized using finite element simulation, and the well-designed PVDF cantilevers with controllable PDMS mass not only reduce the device working frequency but also enlarge the bandwidth. Under a sweep-frequency test, three voltage peaks induced by the piezoelectric part are observed at 15, 32.5 and 47.5 Hz, with the value of 320, 288 and 264 mV, respectively. With the combined triboelectric part, a 20 V peak-peak voltage is generated at 15 Hz. The electrical driving ability of this hybrid energy harvester also has been demonstrated by lighting up a commercial light emitting diode (LED).