Scavenging energy from human body: design of a piezoelectric transducer

The present work concerns the concept and the modeling of a device for transforming a part of the mechanical energy originating from human limb motion into electrical energy. The device is formed by a frame containing a free moving mass. Useful electrical power is generated by the impact of this mass on piezoelectric cantilevers positioned at the end of the frame. In order to evaluate device performances a detailed analysis of the dynamics of the system is coupled to a model of the piezoelectric transducer. It is found that an optimized device, when mounted on the human wrist, can theoretically generate up to 40 /spl mu/W/cm/sup 3/.