Micromachined Thermopiles for Energy Scavenging on Human Body

This paper presents a polycrystalline silicon germanium thermopile specially designed as a power scavenger on human body. The design of both a single thermocouple and the thermopile has been described. The modeling has been performed analytically and numerically. An output power of 1-2 muW with an output voltage of about 1 V can be obtained from the designed thermopiles when installed in a watch-size thermoelectric generator. The relevant material properties of the polycrystalline silicon germanium have been characterized. The thermopile has been fabricated and its functionality has been demonstrated in thermal measurements performed on non-released devices. Under forced convection, the output voltage of a non-released thermopile can reach 53 mV/K/cm² .