Design and performance testing of a dielectric elastomer strain sensor

Abstract

Dielectric elastomer sensors show great potential for wearable devices and soft robots. This paper proposes a method to design, fabricate and parameter optimize of a rectangular sheet dielectric elastomer strain sensor (RS-DESS). The RS-DESS is composed of three VHB 4905 membranes (a commercial product from 3 M company). The central membrane is coated by carbon grease on both sides, serving as a capacitor for sensing. Other two membranes serve as sealing layers to protect the capacitor from damage and pollution. The experimental results show that the capacitance of the RS-DESS increases approximately linearly with the growth of strain at first, then grows slowly and reduces rapidly after reaching a peak. The approximate linear portion of the capacitance response is intercepted as the measuring range of the RS-DESS. The effects of design parameters on the performance of the RS-DESS is tested. It is found that the sensitivity of the RS-DESS will enhance by reducing the length–width ratio and increasing the pre-strain factor. However, it should be noted that the measuring range will reduce as the pre-strain factors increases. Based on comprehensive consideration of sensitivity and measuring range, the optimal ranges of design parameters are selected.