Fabrication and characterisation of highly stretchable elastomeric strain sensors for prosthetic hand applications

This study reports on the fabrication and response characterisation of highly stretchable strain sensors made of two commercially available silicone rubber substrates (EcoFlex 0010, and Shin-Etsu KE-441-T) engraved with microchannels, which are filled with two conductive liquids; carbon nanofibers (CNF) in poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) dispersion (PEDOT:PSS) and liquid carbon black (CB). We experimentally quantified the electromechanical response and strain sensing performance of the sensors using the metrics of linearity, hysteresis, resolution, transient properties and repeatability. We conclude that while changing the conductive liquid mainly affects the overall resistance of the sensors, the sensors made of EcoFlex have (i) overall much faster response characteristics during both loading and unloading cycles, (ii) less hysteresis, and (iii) a smaller time constant, that makes them more suitable to applications in which the input stimulus changes at a fast rate.