Flexible autonomous scavengers: the combination of dielectric polymers and electrets
Abstract
Thanks to their high energy density and their flexibility, scavenging energy with dielectric polymer is a promising alternative to ensure the autonomy of various sensors such as in e-textiles or biomedical applications. Nevertheless, they are passive materials requiring a high bias voltage source to polarize them. Thus, we present here a new design of scavenger using polymer electrets for poling the dielectric polymer. Our scavenger is composed of commercial dielectric polymer (3M VHB 4910) with Teflon electrets developing a potential of -300V, and patterned grease electrodes. The transducer works in a pure shear mode with a maximal strain of 50% at 1Hz. The typical "3D-textured" structure of the scavenger allows the electrets to follow the movement of the dielectric. A complete electromechanical analytical model has been developed thank to the combination of electrets theory and dielectric modelling. Our new autonomous structure, on an optimal resistance, can produce about 0.637mJ.g-1.