Autonomous sensor module powered by impact-enhanced energy harvester from broadband low-frequency vibrations

This work proposes and experimentally validates an autonomous battery-less sensor module based on off-the-shelf electronics powered by a multi-beam piezoelectric energy converter that exploits impact to widen the harvesting bandwidth at low frequency. The module manages the converted energy, interfaces two sensors and periodically sends the measurement signals over a radio-frequency (RF) link. The architecture and principle have been experimentally validated on a fabricated proof-of-concept prototype. The solution that exploits impact increases the overall rms output voltage of the converter of up to 35% and widens the useful bandwidth toward lower frequencies of up to 50% over the no-impact condition at parity of mechanical excitation. In the tested experimental conditions, the prototype features a typical time interval between measurement-and-transmission events of a few seconds, with event durations of the order of tens of milliseconds, corresponding to an operation duty cycle of about 1%. The average power consumption during transmission is of the order of 35 mW with an operative range of 25 m in laboratory environment.