Millimetre-scale bubble-like dielectric elastomer actuators

BACKGROUND: Hydrostatic coupling was recently reported as a means to improve versatility and safety of electromechanical actuators based on dielectric elastomers (DEs). Hydrostatically coupled (HC) DE actuators rely on an incompressible fluid that mechanically couples a DE-based active part to a passive part interfaced to the load. This work was aimed at developing millimeter-scale bubble-like versions of such transducers. RESULTS: Silicone-made oil-filled actuators were manufactured as both single units and arrays of parallel elements. Bubbles had a base diameter of 6 mm and were driven up to a voltage of 2.25 kV, applied across a silicone film with thickness of 42 µm. Active relative displacements and stresses up to 18% and 2.2 kPa, respectively, were recorded with static driving. Dynamic investigations reported a –3dB bandwidth of the order of 100 Hz and a resonance frequency of about 250 Hz. CONCLUSIONS: Millimeter-scale HCDE actuators might play a useful role in several fields of application. Among them, we are currently exploring novel tactile displays and cutaneous stimulators, made of wearable, distributed and flexible devices. Although further miniaturization is required for high-resolution uses, this technology holds promise to properly combine performance with safe and compliant interface with the user, low specific weight, no acoustic noise, and low cost.