Soft materials for soft machines
Speaker: Dr. Lihua Jin - University of California, Los Angeles
Date: Apr 9, 2021; Time: 2:30 PM Location: WebEx
Abstract: Soft machines are transforming the fields of robotics and biomedical devices in that they are capable of sustaining large deformation and interacting safely with human beings. Soft active materials can change their shapes or volumes in response to external stimuli, such as light, heat and electric fields, and are important building blocks of soft machines. The recent advance of 3D printing techniques allows manufacturing of soft materials into complex structures. Designing and fabricating soft structures with predictable actuation and programmable functionalities are the major efforts in the field. In this seminar, I will first talk about our recent progress in controlling and modeling spatiotemporal reconfiguration of soft active materials. By spatially patterning photo-responsive liquid crystal elastomers, we have shown morphing of flat sheets into designed three-dimensional geometry. To predict the spatiotemporal responses of photo-responsive hydrogels, we have developed a nonlinear field theory based on the nonequilibrium thermodynamics to capture the coupled reaction-diffusion kinetics. Further accounting the inertia effect, we have predicted and demonstrated self-excited photo-responsive hydrogel oscillators that can autonomously vibrate under constant light irradiation. Tuning the properties of soft materials through sophisticated chemical synthesis is often challenging. To overcome this limitation, I will demonstrate how we are able to vary the responses of soft materials by designing and fabricating them into mechanical metamaterials, which are materials with microarchitectures. Our efforts in designing phase-transforming metamaterials and energy-absorbing metamaterials will be discussed.
Biographical Sketch: Dr. Lihua Jin is an assistant professor in the Department of Mechanical and Aerospace Engineering at the University of California, Los Angeles (UCLA). Before joining UCLA in 2016, she was a postdoctoral scholar at Stanford University. In 2014, she obtained her PhD degree in Engineering Sciences from Harvard University. Prior to that, she earned her Bachelor’s and Master’s degrees from Fudan University in 2006 and 2009. Jin’s group conducts research on mechanics of soft materials, stimuli-responsive materials, instability and fracture, and soft robotics. Lihua was the winner of Haythornthwaite Research Initiative Grant from American Society of Mechanical Engineers in 2016, Extreme Mechanics Letters Young Investigator Award in 2018, Hellman Fellowship in 2019, and UCLA Faculty Career Development Award in 2020.