Invited: Subsurface Cavitation Dynamics at the Gel-Water Interface

Cavitation dynamics at the liquid-solid interface are central to numerous engineering and medical applications, yet their subsurface effects remain poorly understood due to challenges of measurement. Here, we present a pioneering study using laser-induced inertial cavitation (LIC) to elucidate the intricate dynamics within the gel subsurface due to cavitation events near the gel-water interface. By leveraging the SpatioTemporally Adaptive Quadtree mesh Digital Image Correlation (STAQ-DIC) and Embedded Speckle Pattern (ESP) techniques, we achieve high-fidelity, high-throughput, full-field measurements of deformation, velocity, and strain within soft materials subjected to cavitation at ultrahigh rates. We investigate LIC nucleation at varying standoff distances from gel-water interfaces, gel stiffnesses, and cavitation energy to develop a model for predicting maximum damage. Cavitation events are nucleated within both liquid and solid phases, providing unprecedented quantitative insights into subsurface solid responses to inertial cavitation. Our results reveal the profound impact of nucleation distance on the spatiotemporal deformation behavior, wave propagation, and mechanical strain within the gel, highlighting critical parameters that govern cavitation dynamics at soft interfaces. These findings significantly advance our understanding of how soft biological tissues respond to the violent collapse of cavitation bubbles, offering valuable insights for minimizing collateral damage in cavitation-based medical therapies. This work lays the foundation for improved therapeutic strategies and novel engineering designs that harness the power of cavitation while mitigating its destructive effects.