Novel Thermoelectric Fabric Structure with Switched Thermal Gradient Direction toward Wearable In‐Plane Thermoelectric Generators

Abstract Wearable thermoelectric generators (TEGs) have exhibited great potential to convert the temperature gradient between the human body and the environment into electrical energy for maintenance‐free wearable applications. A 2D planar device structure is widely employed for fabricating flexible TEGs due to its simple structure and facile fabrication properties. However, this device configuration is more appropriate for utilizing in‐plane temperature differences than the out‐of‐plane direction, which limits their application in wearable cases since the temperature difference between the human body and the environment is in the out‐of‐plane direction. To solve this problem, a novel fabric‐based TEG structure that can utilize the out‐of‐plane temperature gradient is proposed in this work. By introducing thermally conductive components in the generator, the out‐of‐plane temperature difference can be switched to the in‐plane direction, which can be further utilized for 2D planar devices in wearable applications. The prepared thermoelectric fabric prototype with only 12 p‐type TE legs exhibits a maximum open‐circuit voltage of 4.69 mV and an output power of 39.7 nW at a temperature difference of 30 K. This strategy exhibits a high degree of versatility and can be readily applied to other 2D planar TEGs, thus expanding their potential application in wearable technology.