A compact electroactive polymer actuator suitable for refreshable Braille display

The large strain, high elastic modulus, and easy processing of poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE)) electrostrictive terpolymer make it very attractive to replace low strain piezoceramics and piezopolymers in many applications with much improved performance. In this paper, a compact polymer actuator is developed utilizing the electrostrictive terpolymer, which is suitable for full page Braille display and graphic display. Key issues related to the reliability of electroactive polymers used in the compact actuators and for the mass fabrication of these polymer actuators are investigated. Making use of a recently developed conductive polymer, a screen printing deposition method was developed which enables direct deposition of very thin conductive polymer electrode layer (<0.1 μm) with strong bonding to the terpolymer surface and short fabrication time. It was observed that the thin conductive polymer electrodes lead to the self-healing of the polymer after electric breakdown. An electroactive polymer (EAP) compact Braille actuator was designed and fabricated with these terpolymer films wound on a spring core. The test results demonstrate that the EAP Braille actuator meets all the functional requirements of actuators for refreshable full Braille display, which offers compact size, reduced cost and weight.