A compact hybridized triboelectric-electromagnetic road energy harvester for vehicle speed measurement

Harvesting the mechanical energy dissipated by vehicles passing over road to power micro-electromechanical systems (MEMS) in intelligent transportation systems (ITS) is an important way to realize self-powered traffic condition monitoring. However, the limitations of traditional vehicle energy harvesting speed bumps such as single functionality and heavy-shock on vehicles are not conducive to developing energy harvesting speed bumps for multi-functionalization, versatility and intelligence. In this work, a compact hybridized triboelectric-electromagnetic road energy harvester (CHREH) device is designed. The vehicle's wheels impact force drives the sliding plate movement and triggers the triboelectric generator (TENG) unit and electromagnetic generator (EMG) unit to produce electricity. The enhanced TENG built by multi-layer folded structure is assembled using rGO and surface-patterning modified polydimethylsiloxane (PDMS) composite film. Furthermore, the mechanism and electrical output performance of EMG and TENG are theoretically simulated and experimentally tested. Particularly, TENG unit achieved a peak power of 7.21 mW and the EMG unit reached a peak power of 0.74 mW at an excitation frequency of 5 Hz, in addition to the superior durability. Further, the demonstration of application of self-powered car warning and speed monitoring were conducted. The CHREH offers a feasible approach for self-powered applications deployable to the low power consumption electronic devices and ITS.