Thermoelectric generator with a high integration density for portable and wearable self-powered electronic devices

This work reports thermoelectric generators (TEGs) for portable and wearable self-powered electronic devices. Two kinds of TEGs, including low (device #1) and high (device #2) integrated number of thermoelectric elements, employing a high performance thermoelectric material fabricated by an assembly technology which are evaluated and compared against each other. Device #1 consists of 17 pairs of thermoelectric elements with dimensions of 1 mm × 1 mm × 2 mm while device #2 has 127 pairs of thermoelectric elements with dimensions of 0.4 mm × 0.4 mm × 2 mm. Both devices are fabricated on the same substrate of 15 mm × 15 mm. Maximum output powers for devices #1 and #2 are obtained as 10.1 mW and 33.9 mW at temperature difference ΔT of 75 °C, respectively, while at low ΔT = 5 °C, those of devices #1 and #2 are 43 µW and 91 µW, respectively. Fabricated TEGs show higher performance in comparison to the recent related works. Moreover, the harvested energy from the fabricated TEG can be stored in a rechargeable battery via a DC-DC converter. The output of the DC-DC converter reaches 2.8 V and 4 V at ΔT = 2 °C and 8 °C, respectively, which corresponds to the DC-DC electronic conversion efficiency η_DC-DC is 8.1% and 23.3%, respectively. The fabricated TEG as a power source for a calculator as well as a twist watch has been demonstrated successfully. The investigation in this work indicated that the fabricated TEG possesses a high potential for portable and wearable self-powered electronic devices.