All flexible graphene strain sensors with liquid metal interconnectors for embedded structural health monitoring and skin tactile sensing

Abstract

This paper reports on the development of graphene strain sensors made of all flexible materials, including graphene, liquid metal, and elastomer. The sensors are featured with a flexible interconnector design using liquid metal as an interconnecting material for graphene-based sensing elements. This design allows enhancing flexibility and reliability of the sensors compared with existing hard metal based interconnection methods. A unidirectional strain sensor and a multidirectional rosette-type strain sensor are developed by encasing patterned graphene and liquid metal in an elastomer. We explore the applications of the unidirectional sensor for structural health monitoring by attaching the sensor on the surface of concrete, and for tactile sensing by attaching the sensor on human skin. This work represents an exploratory effort on using liquid metal interconnectors for graphene-based sensors to obtain full structural flexibility.