Electrostatic actuator for tactile display based on hydraulically coupled dielectric fluids and soft structures

Recent research work has shown that dielectric fluids, with specific properties, can be combined with stretchable or flexible shell structures, made of polymeric dielectric/electrode composite films, to implement a novel type of soft electrically-driven fluidic transducers with self-healing and self-sensing capabilities that take the name of Liquid based Electro-Active Polymer transducers (LEAPs). These devices are similar to dielectric elastomer transducers in regards to their electrostatic working principle, but they can potentially produce larger displacements due to their lower mechanical stiffness. In this contribution, we present a new transducer concept in which LEAP actuators are employed to induce out-ofplane deformation of a membrane. Specifically, experimental and theoretical demonstrations are provided for applications as dot actuator for Braille displays or other tactile feedback implementations. Results obtained on a preliminary prototype show that the system is able to provide a perceivable force for a human fingertip, offering potential room for further improvement and optimization. Electrically-induced cyclic actuation can be produced over a wide range of frequencies. The results presented in this paper prove the applicability of the LEAP principle on tactile devices and show new design paradigms for this technology.