A novel self-starting MEMS-heat engine for thermal energy harvesting

This paper describes a novel micro heat engine for thermal energy harvesting. The engine comprises a working fluid in a sealed cavity, that is bound by a bistable membrane. The engine chamber performs a self-controlled reciprocating motion between a heat source and heat sink. Two types of working fluid are investigated: pure gas and a liquid-gas phase-change medium. A theoretical mechanical output power of is 0.89 ¿W is calculated at a temperature difference of 37°C for the phase change type engine. Measurements at 37°C temperature difference indicate an operation frequency of 0.8 Hz for the phase change engine, compared to 0.16 Hz for the pure gas engine. A maximum of 1.6 Hz is found for the air-filled engine at 100°C temperature difference.