Temperature-induced phase transition of liquid metal for shape-adaptive triboelectric nanogenerator

Flexible wearable electronics are expected to fit different parts of the human body. However, existing energy harvester and sensor still face the difficulties of adhering to complex surfaces and spontaneously fixing to the human body. In this work, a shape-adaptive triboelectric nanogenerator (SA-TENG) based on the phase transition of liquid metal (Cd-In-Sn-Pb-Bi eutectic alloy, LM) has been constructed to achieve efficient wearable energy collection and sensitivity-tunable pressure sensing. The shape-adaptive energy harvester (SA-EH) prepared by constructing hole arrays on the electrode could be directly fixed on different parts of the human body to harvest mechanical energy for driving wearable electronics. It can generate a transferred charge density of 90.5 μC/m² and an average power density of 45.1 mW/m². The natural oxide layer of LM suppresses the loss of liquid electrode and increases the output by 18 % with charge trapping-blocking effect. Furthermore, a sensitivity-tunable pressure sensor (ST-PS) fabricated with microstructures on the surface of SA-TENG can realize the sensitivity of over 2.48 kPa⁻¹ as well as the ultra-wide pressure detection range from 0.42 kPa to 113.17 kPa, and the LM-based shielding layer can weaken external interference. This novel electrode design has greatly expanded the applications of TENGs in wearable electronics.