Exploiting bistable oscillator subharmonics for magnified broadband vibration energy harvesting

International audienceRecent research on primary battery alternatives for supplying autonomous wireless devices have recently highlighted the advantages of nonlinear oscillators' dynamics and more particularly bistable oscillators' behavior for ambient vibration harvesting. The key property of bistable oscillators compared to linear ones is their enhanced operational frequency bandwidth under harmonic excitation, potentially leading to a better adaptation to the environment. However, the classical frequency response characterization of such devices does not reveal all the possible dynamic behaviors offered by bistable oscillators. Thus, subharmonic motions are experimentally investigated in this letter, and their energy harvesting potentials as well as their ability to enhance the bistable generator bandwidth are evaluated. Results obtained with a generator integrating buckled beams for the bistability feature show that, in addition to the commonly considered harmonic behavior, subharmonics allow widening the bistable microgenerator useful operating frequency band by 180 % compared to the sole exploitation of the first harmonic motion