Electromechanical Fatigue Properties of Dielectric Elastomer Capacitive Sensors Based on Plantarflexion of the Human Ankle Joint

Abstract

Highlights Dielectric stretch sensors were subjected to both quasi-static and high-cycle fatigue testing with simultaneous capture of the signal. Under quasi-static loading conditions, the stretch percentage as measured by the dielectric stretch sensor is linearly correlated with the strain measured by the tensile testing instrument. Under high-cycle fatigue testing conditions, the strain as measured by the dielectric stretch sensor and the strain measured by the fatigue testing instrument are poorly correlated. The polymers comprising the dielectric stretch sensor conform to the Rabinowitz-Beardmore model of polymer fatigue undergoing cyclic softening followed by a transition to stability. Stretch sensors may require pre-straining to allow for break-in of the polymeric components to insure the collection of accurate output.