Nature-inspired wearable thermoelectric generator for body heat harvesting

Wearable devices have garnered growing interest for their integration into daily life and potential in health monitoring, environmental sensing, and other applications. To support autonomous and sustainable operation for wearable devices, thermoelectric energy harvesting offers a promising solution by converting body heat into electricity. Inspired by the structure of human skin and hair, a flexible thermoelectric generator (FTEG) wristband with semi-embedded thermoelectric legs and exposed electrodes has been successfully designed and fabricated. Such a structure balances flexibility with enhanced power output, facilitates a greater temperature difference across rigid thermocouples under the limited temperature gradient of the human body. Simulations suggest a theoretical improvement of 170.4% in temperature difference compared to conventional planar structures under the given boundary conditions. Experimental validation with four FTEG prototypes confirms that the semi-embedded structure can effectively enhance the temperature difference by up to 117.12%, depending on the filling factors. The wristband achieves a maximum open-circuit voltage of 107.41 mV on the wrist. Two prototypes of different sizes demonstrated power densities of 8.69 μW/cm² and 13.83 μW/cm² under a wind speed of 1.5m/s, with average temperature-voltage sensitivities of 11.57 mV/^∘C and 17.55 mV/^∘C, respectively. By wearing the prototype on the wrist, the system can provide a stable 3V power supply to a pressure sensor through an energy management module, enabling real-time monitoring of human pulse without the need for external power sources.