A MEMS thermoelectric generator

Abstract

The demand for portable power is large and expanding. Technologies currently available to meet this demand include batteries, fuel cells, thermophotovoltaic (TPV) generators and thermoelectric (TE) generators. Fuel cells and generators offer significantly improved performance over batteries, but issues of fuel processing and miniaturization remain. Microfabrication has the potential to address this miniaturization. Here I present work towards a thermoelectric generator based on micro-electro-mechanical system (MEMS) fabrication technologies. This thesis includes an examination of the current state of the portable power field, followed by an explanation of the thermoelectric effects and the operation of thermoelectric generators. A new analysis of the efficiency of thermoelectric devices, including parasitic losses, is included, with a detailed derivation in an appendix. The design of a prototype MEMS thermoelectric generator is presented, analyzed and fabricated. Testing shows the device performs as expected thermally. However, mechanical fragility causes very low yield during fabrication and limits the high temperature operation. Poor electrical contacts are also observed and characterized. Directions for future work are suggested to improve the efficiency and mechanical strength of the device.