Interface design and material strategies for high-fidelity electrotactile haptic displays

Electrotactile devices can convey touch information in wearable and extended reality hardware. They offer cutaneous stimuli while being free from moving parts. Electrotactile systems often yield sensations that are inconsistent, skin irritating, and unnatural. The dynamism and heterogeneity of skin, the disparate properties between skin and electrode, and the challenge of selectively targeting receptors can cause inconsistencies in stimulation. Previous research has examined stimulus modulation to address these problems. Recent works, however, have expanded to include electrode design, materials, and mechanics for improved stimulation. Conductive polymer and nano-textured electrodes have reduced and stabilized impedances while minimizing obstruction to wearability. Here, we discuss these challenges and their proposed solutions in the literature. We emphasize the role of psychophysical evaluation in obtaining desired tactile percepts. We highlight advancements in electrotactile applications in wearables and interactive surfaces. The convergence of insights in materials, electronics, and perceptual study aims to broaden acceptance and deployment of this technology.