Design and fabrication of a nonlinear resonator for ultra wide-bandwidth energy harvesting applications

A MEMS-scale nonlinear resonator for ultra wide-bandwidth (UWB) energy harvesting applications has been designed and fabricated. Ambient vibration with a varying frequency spectrum is converted directly to electricity via the piezoelectric effect. Unlike most energy harvesters reported, our design utilizes the tensile stretching strain in a doubly-anchored beam [1, 2]. This stretching results in a nonlinear stiffness which provides a passive feedback and consequently a Duffing mode resonance. The doubly-anchored beam structure stores the majority of the strain energy in non-linear stretching and behaves like a frequency locked loop device. This enables the beam´s resonance frequency to track the external vibration frequency until it reaches a point of instability. This paper describes the design, fabrication, and performance of this new energy harvesting device which facilitates this nonlinear vibration mode for small environmental vibrations.