Stimuli-Responsive, Morphing Liquid Crystal Elastomer Structures for Intelligent Systems

Intelligent systems with capabilities of sensing, actuation, and closed-loop control are promising for many applications such as augmented reality, rehabilitation, and soft robotics. In this talk, I will present our work on stimuli-responsive materials, structures, and electronics toward this effort. I will start with our study on liquid crystal elastomers (LCEs), a type of smart material that has capabilities of soft elasticity and large, reversible shape-changing behaviors due to liquid crystal-polymer network couplings. Through introducing a versatile mechanical programming technique, previously inaccessible reconfigurable three-dimensional structures made of LCEs and their magnetic composites are created and their potential applications in soft robotics are demonstrated. I will further present our facile strategy to locally tailor the stiffness and the morphing behavior of these reconfigurable LCE structures by harnessing molecular-material-structure interactions, i.e., locally controlled mesogen alignment and crosslinking densities. Selective photopolymerization of spatially aligned LCE structures yields well-controlled lightly and highly crosslinked domains of distinct stiffness and selective permanent mesogen programming, which enables various previously inaccessible stiffness-heterogeneous geometries, as demonstrated in diverse morphing LCE structures via integrated experimental and finite element analysis. Furthermore, reprogramming of the non-photopolymerized regions allows for reshaping, as shown in a sequentially shape morphing LCE rod and “face”. The heterogenous morphing LCE structures have the potential for many applications including in artificial muscles, soft robotics, and many others. In addition, a simple strategy for creating 3D thermochromic LCE structures with synchronous shape-morphing and color-changing capabilities for biomimetic robotics will also be introduced. I will conclude my talk with soft sensing devices for in situ pressure measurements, beyond the actuation capabilities enabled by LCEs. The introduced actuation and sensing strategies and concepts are promising for many intelligent platforms.