Refreshable Tactile Display Based on a Bistable Electroactive Polymer and a Stretchable Serpentine Joule Heating Electrode

Abstract

The demand for tactile interactive devices has been growing exponentially as the sense of touch enriches the human–machine interaction experience. However, the tactile devices reported so far cannot offer high-quality performance, compact form factor, and relatively simple system architecture for low-cost production. We report the fabrication of a 4 × 4 pneumatic tactile display with Braille standard resolution using a bistable electroactive polymer (BSEP) thin film and a serpentine-patterned carbon nanotube electrode. The BSEP is a variable stiffness material that exhibits a stiffness change of 3000-fold within the narrow temperature range of 43 ± 3 °C. The carbon nanotube electrode was patterned on the polymer film via a P3R process, Prestretch-Pattern-Protect-Release, which leads to a serpentine-patterned composite electrode that is highly stretchable, retains its high electrical conductivity up to an ∼200% area strain, and provides a fast Joule heating rate of 31 °C/s. The tactile pixels are diaphragm actuators that can be individually controlled to produce 0.7 mm out of plain deformation and greater than 50 g of blocking force by application of local heating and pneumatic pressure. The device can operate under low voltage supply (30 V) and has a lifetime of over 100 000 cycles without much performance degradation. This work could open a path to building compact, user-friendly, and cost-effective tactile devices for a variety of important applications