Flow-Active Liquid Marbles as Microreactors for Photocatalytic Micromotors

Abstract

Self-propelled micromotors have shown promise for applications in environmental remediation, sensing, and biomedicine. However, assessing their performance in realistic, 3D microenvironments with dynamic boundaries and complex topography remains a key challenge. Achieving controlled motion and enhanced reactivity under such confinement is critical for both technological applications and fundamental studies on active matter. Here, the integration of light-driven micromotors with liquid marbles is presented, which are gas-permeable droplets encased by hydrophobic particles that act as dynamic, flow-active microreactors. By tuning the coverage of the particulate shell, partially covered liquid marbles are developed that exhibit robust evaporation-induced flows, increasing the average micromotor velocity by approximately threefold compared to sessile droplets. Under illumination, photocatalytic self-propulsion provides an additional velocity component and promotes micromotor dispersion. The combined circulation enhances mass transfer, guiding micromotor accumulation and transport while providing an optical transparent, soft-confinement platform for studying active particles and confined catalytic reactions.