Wearable Graphene Sensors With Microfluidic Liquid Metal Wiring for Structural Health Monitoring and Human Body Motion Sensing

This paper reports on all-flexible strain sensors made of graphene, microfluidic liquid metal, and stretchable elastomer. These graphene sensors feature a flexible wiring design, where liquid metal is introduced into microfluidic channels for wiring inside the devices. This design allows enhanced overall structural flexibility and a reduced risk of stress-related mechanical failure of the sensors, at the contact areas between the graphene sensing elements and the metal wires. A unidirectional strain sensor and a multidirectional rosette strain sensor are developed, by encasing patterned graphene and microfluidic liquid metal channels with a stretchable elastomer. We demonstrate the use of the developed unidirectional strain sensor for structural health monitoring of curved concrete structures, and for tracking the angular motion of a human wrist. The multilayer rosette strain sensor is shown to be capable of detecting the amplitude and angle of a primary strain in a multidirectional strain field.