Metal thermoelectric harvester for wireless sensors

A metal thermoelectric energy harvester design with long metal couples was investigated for use with wireless sensors in environments where conventional thermoelectric harvesters are difficult to implement. Two thermoelectric harvesters with different designs was assembled by spot welding 110 μm thick molybdenum foil and 150 μm thick nickel foil together in a zigzag-pattern, one 3-couples design (55 mm length and 6 mm width) insulated with glass fiber at the hot side and polyimide tape at the cold side, and one 10-couples design (300 mm length and 3 mm width) insulated with polyimide tape across the entire length. The voltage- and power output were measured at different temperatures and load resistance with maximum power output of 588 μW at 269 °C for the 3-couples harvester and 868 μW at 241 °C for the 10-couples harvester. The power output after power management electronics for the 10-couples harvester measured 290 μW at 51 mV. The harvesters were compared to a conventional semiconductor thermoelectric device coupled with a 300 mm long copper heat bridge giving a power output after power management electronics of 170 μW at 41 mV with 226 °C temperature gradient of the environment. (paper)