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MAE Seminar: “Soft materials for soft machines”
November 4 @ 10:00 am - 11:00 am
Soft machines are transforming the fields of robotics and biomedical devices in that they are capable of sustaining large deformation and interacting safely with fragile objects and human beings. The recent advance of additive manufacturing allows fabrication of soft materials into complex structures. Designing and fabricating soft structures with programmable actuation and desired functionalities are the major efforts in the field. In this seminar, I will first talk about our recent progress in controlling spatiotemporal reconfiguration of stimuli-responsive soft materials (SRSMs), which are important building blocks of soft machines. SRSMs can change their shapes or volumes in response to external stimuli, such as light, heat and electric fields, through non-equilibrium kinetic processes. Using hydrogels and humidity-responsive polymers as model SRSMs, I will demonstrate how to predict their spatiotemporal responses by developing non-equilibrium field theories, and program their spatiotemporal reconfiguration by patterning the materials using advanced manufacturing tools. Further utilizing the interplay between SRSMs and external stimuli, and coupling of their kinetics and inertia allows us to achieve autonomous oscillation and self-sustainable actuation of SRSMs. However, tuning the properties of SRSMs 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 shape-transforming metamaterials and energy-absorbing metamaterials will be discussed.
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, soft robotics, and biomechanics. 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, UCLA Faculty Career Development Award in 2020, and NSF CAREER Award in 2021.