The need for speed

Abstract

Development of dielectric elastomer actuators has been mainly targeted towards achieving giant static strain with little attention paid to their response speed, which can, depending on materials used, be as long as tens of seconds. However, most of the practical applications require actuators capable of changing shape quickly, therefore a careful choice of materials and technologies for the dielectric and electrodes must be made. Test oscillating actuators, made with a range of silicone membranes with different hardness were tested, and the compliant electrodes were made with different technologies: carbon powder, carbon grease, conductive rubber and metal ion implantation. The transient response of the actuators to a step input was measured with a high speed camera at 5000 frames per seconds for the different combinations of membrane material and electrodes. The results show that the dynamic response of the actuators is extremely dependent on the membrane material, as expected, but also on the compliant electrodes, whose impact cannot be neglected.

Ultrafast All‐Polymer Electrically Tunable Silicone Lenses

“…Because of the design of the lens, the same membrane is used as dielectric for the actuator and as membrane encapsulating the liquid. In order to increase the device's tuning speed, we choose silicone membranes for the actuator, [11] and hence also for the lens. However, silicone elastomers are gas permeable, and swell when in contact with many non-polar liquids.…”

Improved electromechanical behavior in castable dielectric elastomer actuators

“…Pelrine et al have reported, in 2000, a 117% uniaxial linear strain with an actuator patterned as a long strip on a uniaxially prestretch silicone elastomer. 1 More recently, Rosset et al have shown a 60% linear planar strain on a PDMS based DEA with rise time of less than 10 ms. 8 However, the existing theoretical guidelines for large actuation deformation of DEAs developed based on VHB films cannot be directly implemented to castable elastomers. 9,10 Unlike VHB, which is available as films with predefined thicknesses, PDMS or polyurethane are initially a resin and can be casted to form membranes of any desired thickness.…”

Assessing the degradation of compliant electrodes for soft actuators

“…the frequency at which the actuator can be charged and discharged). If it becomes smaller than the mechanical bandwidth, then the actuator becomes electrically-limited 29 .…”

“…As the data acquisition during the acquisition cycle is done in a quasi-static state, it is important to select a frequency for the cyclic actuation that is not too high, in order to ensure the same actuation stretch during the ageing phase and during the measurement phase. The mechanical bandwidth is dominated by the dielectric membrane material, although we have also previously shown that the electrodes have an impact on the response speed of DEAs 29 . We have characterised the stretch amplitude of an actuator made using a low-mechanical loss silicone (Dow Corning Sylgard 186.…”