A novel thermal imaging approach to visualize current flow distributions in electrodes for dielectric elastomer transducers

Dielectric elastomer transducers (DETs) are used in various applications, ranging from actuators to sensors and generators. For optimal performance, homogeneous electrical charging characteristics, which depend on the current flow distribution over the electrode area, are indispensable. To enable the investigation of such current flow distributions, a novel approach using thermal imaging (TI) is presented in this paper. The approach uses high-frequency voltage excitation to induce resistive heating in the DET electrodes and generates temperature maps to visualize the current flow, thus providing insight into the local charging behavior. This way, the effects of electrode geometry, electrical contact layout as well as potential manufacturing-related imperfections can be studied. The paper starts by introducing an experimental setup and the effect of excitation parameters. It subsequently illustrates the method using 50 µm strip-shaped silicone films with different screen-printed carbon black/PDMS electrodes, also taking the effect of mechanical strains into account. The results allow for an interpretation of the effectiveness of electrode design, motivate potential future quality tests and may serve as a validation method for, for example, multi-physics finite element simulation tools.