The NERD setup: assessing the life time of electrodes for dielectric elastomer transducers

Abstract

DEAs used in applications such as tunable lenses, soft robotics, etc. are expected to survive many thousands to millions of stretching cycles without degradation of their performance. Here, we present a measurement technique to characterise the evolution of the resistance of compliant electrodes submitted to cyclic biaxial strain, which represents the stretching configuration to which DEAs are usually submitted. We apply the novel electrode resistance degradation (NERD) method to the characterisation of compliant electrodes obtained by inkjet printing a carbon black suspension. We show that although the electrodes can sustain 1 million cycles of stretching at 5%, a 10% cyclic strain causes a much faster degradation, leading to a reduced actuation strain over time. We show that increasing the thickness of the electrodes leads to cracking and accelerated degradation; two layer electrodes degrade more rapidly than single layer electrodes. The NERD setup represents an efficient tool to quickly evaluate the suitability of different electrode formulations for use as compliant electrodes for DEAs.