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

Abstract

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.

Multifunctional liquid metal polymer composites

“…(C) Photo sequence of printed LM‐LCE composite actuating, experiencing deformable loading, and returning to the programmed actuation shape. Reproduced with permission, 131 copyright 2021, Wiley‐VCH. (D, E) A demonstration of programmed caterpillar‐like actuation from LM‐LCE using near‐infrared light and an accompanying visual diagram.…”

“…Therefore, enhancing LCEs thermal conductivity through integration with LMPCs would complement those characteristics. For instance, a study developed a new way of fabricating LM‐LCE composites by using EGaIn as a LM core and liquid crystal elastomer as a shell that can be coextruded from a 3D printer 131 . This fiber‐like design benefited from relatively large LM cross‐sections that enabled high current/low voltage joule heating to raise the liquid crystals above their nematic‐isotropic‐transition temperature, forcing them to change alignment and contract the elastomer matrix.…”

Progress in Utilizing Dynamic Bonds to Fabricate Structurally Adaptive Self‐Healing, Shape Memory, and Liquid Crystal Polymers

“…Direct ink writing (DIW) is the most commonly used method for 3D printing of LCEs. [ 274–279,282,283 ] The LCE ink can be directly extruded out of the printing nozzle and then deposited on the printing platform to build a three‐dimensional structure. Mesogens can be aligned along the printing path due to the shearing and dragging force from the nozzle.…”

“…The use of 3D printing in preparing LCE actuators, including the fabrication of mesogen orientation and macroscopic shape design, has also become a research hotspot in this field. [274][275][276][277][278][279][280][281][282] However, materials suitable for printing are still limited due to the necessary mesogens orientation and rheological property of ink. Therefore, the combination of dynamic LCE network with 3D printing will certainly enrich the variety of LCEs suitable for 3D printing.…”

“…Direct ink writing (DIW) is the most commonly used method for 3D printing of LCEs. [274][275][276][277][278][279]282,283] The LCE ink can be directly [269] Copyright 2019, Wiley-VCH GmbH. c) Synthetic route of LCNs with allyl sulfides.…”