Liquid Crystal Elastomer-Based Haptic Pixel Arrays at Your Fingertips for Advanced Human-Machine Interfaces

The sense of touch is underutilized in our digital lives, especially when compared to the prevalence and complexity of information transfer through our visual and auditory interactions with devices; the impact of this is profound as touch plays a major role in our perception of our world, and its omission in our commonly used devices limits our accessibility to the digital space, particularly for blind and visually impaired users. Fortunately, the stimuli-responsive shape-morphing properties of liquid crystal elastomers (LCEs) promise a solution: in our work, we mechanically program an LCE bilayer coating to achieve durable, high-amplitude switchable surface protrusions, or tactile pixels, which we assemble into a digital platform for generating tactile images and haptic feedback. We further characterize and describe our tactile pixel design by microscopy techniques and simulations that use the neo-classical theory of rubber elasticity. We demonstrate safe and effective electronically addressable activation of individual LCE pixels within seconds, accompanied by a psychophysical evaluation of tactile line orientation discrimination in which the performance of our LCE tactile pixels is comparable to swell paper, a standard tactile graphic medium. Thereby, we establish LCEs as a contender for the next-generation dynamic tactile displays.