Collaborative Research: From Waves to Motion - Harnessing Focused Ultrasound for Adaptive Dynamics in Liquid Crystal Elastomers

Shape-changing materials are emerging for advanced manufacturing, soft robotic systems, and medical technologies. Many smart materials require direct heating, light, or embedded components for actuation, limiting their use in complex or hard-to-reach environments. This project investigates a way to remotely control soft materials using focused ultrasound, a noninvasive form of energy that can be delivered precisely to a selected location. The research focuses on liquid crystal elastomers, soft polymers that undergo large, reversible shape changes when their internal molecular order is altered. By combining material programmability with the spatial precision of focused ultrasound, the project will create new knowledge for remotely activated, reconfigurable materials. The results may support advances in four-dimensional printing, where printed materials change shape or function over time, as well as soft robotic devices, adaptive structures, and biomedical technologies, contributing to national needs in advanced manufacturing, artificial intelligence, and biotechnology. The project will train graduate and undergraduate students through hands-on, interdisciplinary research that integrates materials science and acoustics. It will support classroom modules, cross-institutional student exchange between Virginia Tech and the University of Southern California, and outreach through science festivals and K–12 robotics open house events that introduce students to smart materials, ultrasound science, and emerging engineering careers. This project establishes a predictive framework for ultrasound-driven actuation of liquid crystal elastomers across molecular, material, and structural scales. The research will first characterize how focused ultrasound produces localized heating, phase transition, shape change, and recovery in programmed liquid crystal elastomer samples. Experiments will measure temperature fields, deformation histories, material properties, and actuation behavior as functions of ultrasound conditions and material architecture. Molecular dynamics simulations will examine how mesogen reorientation, polymer network relaxation, viscoelastic energy dissipation, and internal friction contribute to ultrasound-induced heating and deformation. These molecular-scale results will be connected to continuum-scale constitutive models that describe anisotropic, nonlinear, and temperature-dependent deformation of liquid crystal elastomers. The project will integrate acoustic wave propagation, heat transfer, molecular dynamics, solid mechanics, and physics-informed artificial intelligence into a validated modeling platform. This framework will be used with inverse design and autonomous optimization methods to identify combinations of material geometry, molecular alignment, crosslink density, ultrasound frequency, intensity, focal position, and exposure duration that produce target shape transformations while maintaining thermal and mechanical constraints. The expected contribution is a set of experimentally validated principles, computational tools, and artificial-intelligence-enabled design methods for creating ultrasound-responsive soft materials with spatially targeted, reversible, and efficient actuation. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.