Liquid crystal elastomers in soft micro electromechanical systems: a review of recent developments

Liquid crystal elastomers (LCEs) are a class of electroactive polymers (EAPs) that have attracted significant attention in the microelectromechanical system (MEMS) community due to their unique combination of properties, including different actuation mechanisms, high generated strain (up to 400%), preprogrammed deformation, and biocompatibility. LCEs have the potential to revolutionize MEMS devices by enabling the development of miniaturized actuators, sensors, and other functional components with enhanced performance. This review provides a comprehensive overview of LCE-based devices for MEMS applications. It begins by exploring the fundamentals of LCEs, delving into their core component, liquid crystals (LCs). Subsequently, it examines the LCE preparation process, encompassing synthesis techniques, and alignment mechanisms. The review then delves into the state-of-the-art LCE-based devices used in MEMS, discussing their functionalities, characterization, and fabrication methods. A particular focus is placed on cutting-edge methods for integrating LCEs with MEMS using compatible fabrication techniques. Looking towards the future, the review introduces ionic liquid crystal elastomers (iLCEs) as a promising novel class of LCE-based materials with the potential to address limitations and enhance the performance of conventional LCEs in MEMS. Finally, a conclusion lays out future research orientations in iLCE-based MEMS technologies and the challenges that remain to be addressed in order to further expand their applications.