4D Printing Liquid Crystalline Actuators toward Assistive Devices

Liquid crystal elastomers (LCEs) are potential artificial muscle candidates within patientassistive devices. Their stimuli-responsive, shape-morphing properties can be controlled by various processes to produce a wide range of actuation behaviors. However, there are inherent processing limitations that inhibit their application within biomedical devices: 1) force and work constraints due to size restrictions, 2) high activation temperatures (≥ 100 °C) to induce actuation, and 3) incompatible power delivery. The aim of my research is to develop manufacturing processes to fabricate three-dimensional LCE artificial muscles compatible with patient-assistive devices. The developed 4D printing process enables control over geometry and liquid crystalline orientation to develop 3D LCE structures with improved actuation behaviors. The development of tunable, printable LCE chemistries allows for low-temperature activation suitable for human body interfacing. Incorporation of liquid metal fillers generates a multiresponsive LCE composite compatible with facile power delivery systems, i.e., current and light. The enabled processing freedom for this class of LCEs can be exploited within a myriad of assistive devices ranging from untethered, implantable dynamic valves to wearable, rehabilitative artificial muscles.