2025 SES Huajian Gao Yong Investigator Medal Lecture 1

Autonomous locomotion of non-equilibrium stimuli-responsive soft materials

One recent impetus of developing stimuli-responsive soft materials (SRSMs) is to use them for soft robotics. However, achieving robotic locomotion of SRSM typically requires sophisticated control of external stimuli in coordination with their movement. In this talk, I will demonstrate complex and autonomous locomotion of SRSMs under simple stimuli control by steering their non-equilibrium thermodynamic processes. SRSMs change their shapes, structures or functions in response to external stimuli through non-equilibrium processes, including diffusion, reaction, viscoelastic relaxation, etc. These processes not only determine the response speeds of SRSMs, but also govern how they spatiotemporally evolve their shapes, structures and functions. In this talk, I will first describe how constant light can trigger self-excited oscillation of a hydrogel cantilever. Second, a humidity-responsive film will be shown to undergo continuous reconfiguration and oscillation in a fixed humidity chamber. Third, I will showcase programmable shape-morphing and locomotion of shape memory polymers by varying the material and loading conditions. Finally, I will present an autonomous, unidirectional, untethered, and sustainable soft crawler made of photo-thermal liquid crystal elastomers.

Bio of the speaker: Lihua Jin is an associate 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. Lihua conducts research on mechanics of soft materials, stimuli-responsive materials, instability and fracture, soft robotics, and biomechanics. She was the winner of the Haythornthwaite Research Initiative Grant, Extreme Mechanics Letters Young Investigator Award, Hellman Fellowship, NSF CAREER Award, ACS PMSE Early Investigator Award, Sia Nemat-Nasser Early Career Award, and SES Huajian Gao Young Investigator Medal.