Bistable springs for wideband microelectromechanical energy harvesters

This paper presents experimental results on a microelectromechanical energy harvester with curved springs that demonstrates an extremely wide bandwidth. The springs display an asymmetrical bistable behavior obtained purely through their geometrical design. The frequency down-sweep shows that the harvester 3-dB bandwidth is about 587 Hz at 0.208-g acceleration amplitude. For white noise excitation at 4×10−3 g2/Hz, we found that the bandwidth reaches 715 Hz, which is more than 250 times wider than in the linear-spring regime. By varying the bias voltage, an output power of 3.4 μW is obtained for frequency down-sweep at 1-g amplitude and 150-V bias.