Core-free rolled actuators for Braille displays using P(VDF–TrFE–CFE)

Abstract

Refreshable Braille displays require many small diameter actuators to move the pins. The electrostrictive P(VDF–TrFE–CFE) terpolymer can provide the high strain and actuation force under modest electric fields that are required for this application. In this paper, we develop core-free tubular actuators and integrate them into a 3 × 2 Braille cell. The terpolymer films are solution cast, stretched to 6 μm thick, electroded, laminated into a bilayer, rolled into a 2 mm diameter tube, bonded, and provided with top and bottom contacts. Experimental testing of 17 actuators demonstrates significant strains (up to 4%) and blocking forces (1 N) at moderate electric fields (100 MV m−1). A novel Braille cell is designed and fabricated using six of these actuators.