A Low-Threshold Bistable Device for Energy Scavenging from Wideband Mechanical Vibrations

In this paper, the results of the investigations on a system for energy harvesting from wideband vibrations are presented. The harvester adopts a nonlinear snap-through buckling configuration and two piezoelectric transducers, placed near the inflection points of the potential energy function that underpins the dynamics of the system. The device is capable of scavenging energy from vibration sources in the range of 0.5-7 Hz, but could be exploited up to 10 Hz with an acceptable loss of efficiency. The bandwidth of the device is compatible with applications where the vibrations occur at low frequencies, e.g., in the case of a running human. Powers of about 416μ W with root-mean-square accelerations of 13.35 m/s2 at 7 Hz and an efficiency of about 24.6% have been measured in case of a sinusoidal vibration while powers of about 250 μ W and an efficiency of about 15.7%, have been measured in case of a noise input limited at 15 Hz, with a standard deviation of the accelerations of about 15.1 m/s2. The performance of the harvester is compared with a different configuration where the piezoelectric transducers are placed at the two minima of the (bistable) potential energy function that underpins the dynamics; the minima correspond to the stable states of the beam.