Transparent and Electrically Switchable Thin Film Tactile Actuators Based on Molecular Orientation

TL;DR

This paper introduces a novel transparent tactile actuator that uses liquid crystal molecular orientation changes under electrical fields to produce tactile sensations, offering rapid and chemically-based tactile feedback for haptic interfaces.

Contribution

It presents a new class of tactile actuators based on molecular rearrangement in liquid crystal-polymer films, enabling quick, chemically-driven tactile sensations.

Findings

Humans can distinguish tactile differences based on molecular orientation changes.

The tactile sensation occurs in less than 17 milliseconds.

The mechanism relies on microscale phase separation and molecular orientation, not surface topography.

Abstract

Most tactile actuators create tactile sensations through vibrations or the mechanical and electrochemical formation of bumps. However, tactile sensations of real objects arise from friction which is derived not only from physical topography, but also surface chemistry. Here, we show that molecular rearrangement can be leveraged to create new classes of tactile actuators based on the phases of liquid crystals embedded in a solid and transparent polymer film. We found that humans can feel differences by touch, especially between planar alignment and its disrupted phase, as actuated by a DC electrical field. In subjective terms, the sensation was described as a tacky to polished-like feeling. We attribute the mechanism of tactile contrast to microscale phase separation and changes in molecular orientation, as the nanoscale differences in topography are too small to be detected on their own by humans. This molecular rearrangement occurs quicker (<17 ms) than actuation through ionic or fluid movement. This enables a new class of tactile actuators based on molecular orientation (TAMO) for haptic interfaces.