An active piezoelectric energy extraction method for pressure energy harvesting

Abstract

This paper presents an energy harvesting technique to power autonomous systems and more particularly active implantable medical devices. We employ a piezoelectric diaphragm placed in a fluidic environment such as blood subjected to very low frequency (2Hz) pressure variations that is deflected in a quasi-static manner and transduces mechanical energy into electrical energy. In order to maximize energy generation and to get the most out of a given piezoelectric device, we propose to apply an optimized method to extract the piezoelectrically generated charge through the application of a controlled voltage. We believe that this method could be one of the improvement levers to achieve self-powered miniaturized implants. An analytical model is presented and shows that within its validity domain, the extracted energy is proportional to the desired applied voltage. Taking power electronics losses into account can yield a theoretical increase in the extracted energy of several thousand per cent. Experimental measurements in a pressure chamber have been carried out whose results corroborate the proposed model. For the tested setup, the application of a 10V peak amplitude square-wave voltage increased the extracted energy by a factor of nine compared to a classical rectifier-based energy harvesting method. © 2012 IOP Publishing Ltd.