High voltage photoconductive switches of amorphous silicon for electroactive polymer actuators

Abstract Dielectric elastomers exhibit remarkable elastic and electroactive properties. Upon kilovolt range electrical stimulation, the polymeric actuator deforms with very large mechanical strain. We made thin film amorphous silicon (a-Si:H) photoconductive switches on 50-μm thick flexible polyimide films to control the polymer actuation. 155–310-nm thick a-Si:H films were grown by plasma enhanced chemical vapor deposition at 150 °C substrate temperature. The photoconductive switches were made with 250-, 500- or 1000-μm gaps formed by electrodes of evaporated aluminum. When properly passivated, the switches have a dielectric breakdown strength of ∼10 kV/mm across the gap. We present optical and electrical characteristics of these a-Si:H switches in the 1–10 kV range. The integration of a nine-element a-Si:H high voltage photoconductor switch array with a nine-element electroactive polymer actuator array is demonstrated. The time constants measured on this array agree well with the values modeled using the a-Si:H photoconductor characteristics.