A study of conductive thermoplastic elastomeric polyurethane and graphene nanocomposite thin films for application to flexible electrical sensors

Pressure-sensitive thin film is one of the major components in flexible electrical sensors (e-skin sensors). The thin film are normally conductive and durable. However, its applications are often limited, due to its big noise and hysteresis. In this research, we developed a new nanocomposite made with thermoplastic-polyurethane (TPU) and graphene to measure contact pressure. To ensure a minimum noise level in the measurement, we prepared it through an iterative heating, sonication, and phase inversion process. Then we studied the relationship between the measured resistance and applied force through the comprehensive consideration of the graphene weight percentage, the size of the sensing elements, and the loading/unloading speed. We also characterised its hysteresis and repeatability. Finally, the nanocomposite with the best comprehensive results was selected and stencil-printed in the holes on a polydimethylsiloxane film to be used as the sensing element of e-skin sensors.