Multicolor electrochromic actuators for biomimetic skin-muscle coupling

Soft robotic platforms require actuators that integrate robust mechanical actuation with dynamic visual feedback; however, achieving muscle-like actuation alongside optical transduction in a compact form factor remains challenging. Here, we present a multicolor electrochromic actuator (ECA) that delivers large-strain, muscle-like contraction and RGB optical output by synergistically integrating a thermoresponsive liquid crystal elastomer (LCE) with viologen-based electrochromic ion gels. A transparent LCE layer embedded with a zinc-mesh heater enables reversible contraction via uniform Joule heating. Three laterally patterned, independently addressable electrodes support RGB ion gels, achieving crosstalk-free coloration with high optical contrast, reversible switching, and operational stability. Despite its thin, lightweight architecture, the ECA lifts substantial loads while providing tricolor visual output when mounted on robotic structures. This multifunctional coloration-and-actuation architecture embodies biomimetic skin–muscle coupling, offering a compact, adaptive strategy for soft robotics and wearable technologies.