Polydimethylsiloxane structure as a broadband vibrational energy harvester

In this paper, a broadband vibrational energy harvester based on a bistable nonlinear geometric structure using soft material polydimethylsiloxane (PDMS) has been developed. First, a nonlinear geometric PDMS multilayer structure has been fabricated by bonding two prestressed thin PDMS films on both sides of another flat PDMS film. After releasing the prestress, the multilayer PDMS structure settles into two cylindrical configurations. An analytical model of these multilayer shapes has been developed using classical lamination theory along with a Rayleigh-Ritz approximation technique. This model shows good agreement with the experimental results. A bistable energy harvester based on this nonlinear geometric bistable PDMS structure has been proposed. The low stiffness of the PDMS material allows working frequency lower than 10 Hz. The dynamic response of this generator under small input excitation shows a hardening spring system, before the strongly nonlinear snap through effect occurs. This hardening spring system is able to broaden the bandwidth of the energy harvesting device.