Deformocouple: A Self-Powered Strain Sensor with Intrinsic Stretchability

Flexible strain sensors show immense potential for health monitoring, robotics, and a wide range of related applications. However, conventional sensors are often limited by their reliance on external power, restricted flexibility/stretchability, and complex fabrication processes. To address these challenges, this work proposes a novel self-powered strain sensor based on an innovative structural design and operating principle. The device comprises two bonded flexible polymer films, forming a built-in electron exchange system. During deformation, electrons in the two films are redistributed and exchanged, generating an electrical output signal directly proportional to the applied strain. This fundamental mechanism is akin to the thermoelectric effect in thermocouples, where a couple of thermoelectric materials generate voltage in response to temperature differences. Consequently, this device is termed as "deformocouple" and the constituent materials are termed as "deformoelectric materials". Ti₃C₂ MXene was strategically employed as a functional filler to tune the deformoelectric properties of the polymers. The resulting deformocouple sensors eliminate the need for external power, offer versatile material compatibility, and exhibit excellent flexibility and stretchability. These attributes underscore the significant value and broad potential of deformocouples within self-powered sensing technologies.