Innervated, Self‐Sensing Liquid Crystal Elastomer Actuators with Closed Loop Control

The programmable assembly of innervated LCE actuators (iLCEs) with prescribed contractile actuation, self‐sensing, and closed loop control via core–shell 3D printing is reported. This extrusion‐based direct ink writing method enables coaxial filamentary features composed of pure LM core surrounded by an LCE shell, whose director is aligned along the print path. Specifically, the thermal response of the iLCE fiber‐type actuators is programmed, measured, and modeled during Joule heating, including quantifying the concomitant changes in fiber length and resistance that arise during simultaneous heating and self‐sensing. Due to their reversible, high‐energy actuation and their resistive feedback, it is also demonstrated that iLCEs can be regulated with closed loop control even when perturbed with large bias loads. Finally, iLCE architectures capable of programmed, self‐sensing 3D shape change with closed loop control are fabricated. Self‐sensing, innervated liquid crystal elastomers in both fiber and square spiral motifs (shown) are produced by core–shell 3D printing. The printed core–shell filaments consist of a liquid metal core surrounded by a liquid crystal elastomer shell. When Joule heated above their nematic‐to‐isotropic transition temperature, these self‐sensing architectures exhibit actuation and large work output, which can be regulated via closed loop control. ​