Transparent strain-insensitive stretchable ionic temperature sensor with MXene enhanced performance

Temperature is a fundamental physical quantity. With the rapid development of stretchable electronics, transparent stretchable temperature sensors are in critical demand. However, performance retention under strain is a great challenge, and the influence of the electrode on the sensing performance is rarely reported. Here, a transparent strain-insensitive stretchable ionic temperature sensor is developed, whose sensing performance is enhanced through an electrode engineering strategy by inserting MXene between two Ag NWs layers. MXene largely increases the electrode’s adhesion strength to the ionogel electrolyte, and hinders ion adsorption while, in the meantime, bonds with neutral ion pairs whose dissociation enhances with increasing temperature. The strain-insensitive sensing performance is mainly ascribed to a crack counteraction mechanism, where the boosting effect of the expanding electrode area as strain enlarges is counteracted by the decline in conductive paths owing to widening cracks. This crack counteraction mechanism is quantitatively verified through theoretical simulation. The sensor is demonstrated for various applications, including smart prosthetic hands, motion tracking, and temperature monitoring of a deforming surface. This work could inspire new stretchable sensor designs and guide strain-insensitive stretchable electronics.