Bandwidth tunable vibration energy harvester based on hybrid triboelectric-piezoelectric array

In this work, we present a highly effective and scalable design strategy of a triboelectric-piezoelectric hybrid array of three cantilever beams stacked over each other (wideband operation regime), which can also be rotated around their mean position to vibrate freely without impacting any other layer (narrowband operation regime). Contrary to a unique frequency response exhibited by conventional devices, the proposed device can switch between narrowband and wideband frequency responses around different central frequencies. This work elaborately discusses the frequency response of mechanical stopper-based PEG and TEGs at varying gap lengths, excitations, and resonant frequencies, and the design of the hybrid array is optimized based on it. The performance of this device is characterized using simulation analysis and experimental validation. Experimentally, the device generates net power greater than 0.3 mu W (Piezoelectric) and 0.4 mu W (Triboelectric) continually between the frequencies of 30 to 60 Hz in the wideband operation regime and output power of 0.81 mu W, 0.65 mu W, and 0.62 mu W at 27,36 and 45 Hz in the narrowband operation regime under mechanical excitation of 0.75g. The remarkable performance of the device at different frequency ranges demonstrates its potential in various harvesting and sensing applications.