A disruptive technology for thermal to electrical energy conversion

A disruptive approach to thermal energy harvesting is presented. The new technique can be used for powering ultra-low power electronics. We propose a two-step conversion of heat into electricity: thermal to mechanical accomplished with thermal bimetals and mechanical to electrical accomplished with piezoelectrics. Devices can work in a wide range of temperatures: from −40 °C to 300 °C and the available mechanical power density is in the order of 1 mW/cm2. The first electrical results and the first prototype built on a flexible substrate are presented in this work. We evidenced that one of the keys to improve the generated power density is downscaling of individual devices. To demonstrate this point, laws modeling downscaling have been established and show that the miniaturization of the devices by a factor k increases the generated power density by the same factor, due to the higher heat transfer rate. The path followed in order to establish the laws is given in this paper.