Conformal Cu–CuNi Thermocouple Using Particle-Free Ink Materials

Flexible electronic sensors are today trending toward being smaller, lighter, and also conformal, while additive manufacturing capabilities are proving crucial in their rapid prototyping. Here, we report flexible and conformal thermocouples by printing liquid metal–organic decomposition materials, consisting of Cu and CuNi particle-free conductive inks. The printed Cu–CuNi (type T) thermocouple shows a linear temperature response with a sensitivity of 20.6 μV/°C and a response time below 2 s. In addition, the printed flexible thermocouple sensor exhibits high stability and reliability when subjected to external stimuli, such as bending, humidity, and thermal cycling. Printed conformal thermocouples using liquid metal decomposition ink materials provide a promising avenue toward miniaturized hybrid electronic devices.