Characterization of a Bulk-Micromachined Membraneless In-Plane Thermopile

This paper describes the characterization method and results for bulk-micromachined in-plane thermopiles. Made of poly-Si or poly-SiGe, the thermocouple legs bridge the hot and cold side of a Si frame, which is formed by bulk micromachining. The characterization of the fabricated devices is carried out on a dedicated experimental setup, using which a uniform temperature difference can be imposed on all the thermocouples. Among design variations, the open-circuit output voltage reaches up to 95.0 mV/K and the corresponding output power on a matched external load is 2.34 × 10⁻³ μW/K². Two possible assembly schemes towards a fully fledged thermoelectric generator are illustrated as well. In the case of vertical assembly, the efficiency factor is expected to be 1.73 × 10⁻² μW/K²/cm².