Twisting Liquid Crystal Elastomer Fibers to Realize Fast and Slow-Twitch Thermomechanical Response

Liquid crystal elastomers (LCEs) have been studied extensively and considered for functional use in applications such as soft robotics, smart textiles, and medical devices. LCEs undergo an ordered to disordered transition causing them to contract. The associated deformation in LCE fibers is analogous to muscles. This research is concerned with characterizing the orientation of LCE fibers in a twisted geometry and assessment of the thermomechanical response. We will show that the thermomechanical response of twisted LCE fibers spans a distinct geometric phase space. The fibers start in a rectilinear geometry and then spontaneously coil when heated. The inherent stimuli response of LCEs changes the twist density of the LCE fibers. The stimuli-response is dependent on the morphological constraints of the fibers (e.g., the twist density). A material with a fixed twist density can have different geometric actuation responses based on the load or force that is needed to be generated. Using the spontaneous coiling for actuation leads to fast actuation responses, increase in actuation stroke and ability to optimize work.