Preparation and characterisation of stacked planar actuators

Abstract

Dielectric elastomer transducers (DETs) consisting of thin elastomeric membranes trapped between two electrodes are emerging technology for electromechanical soft actuators, sensors and energy harvesters. Among the current challenges in DE actuators are the reduction of driving voltage by acting on the mechanical and dielectric properties of the active membrane, by ensuring a good dielectric-electrode compliance or by optimal configuration of the device. Taking into account the significant influence of the Young’s modulus on the actuation strain, in this paper, a silicone elastomer customized in terms of molecular weight and crosslinking pattern was prepared and characterized. By appropriate testing, it was found the optimal carbon black-based electrode formulation and both single layer and 30-layer stacked actuators (DET-Si-cb-30) were built. While the former was electromechanically evaluated by measuring the lateral actuation strain, the contractive actuation strain was measured for the stacked array. The stacked arrangement was evaluated by two nonconventional protocols for the DETs field: shearing behavior using a “resonant column” and actuation force by attachment of different weights. Comparison of results with those obtained on similar configurations based on recognized dielectric elastomers (Elastosil and VHB-4910) as references, evaluated under identical conditions, highlights superior capabilities of DET-Si actuator. Thus, DET-Si-cb-30 can lift 250 times its weight at only 20 V·µm−1 while Elastosil-cb-30 can lift 220 times and VHB-200%-cb-30 10 times its weight.