Reconfigurable multibeam engineering of Marangoni convection for programmable optofluidic steering.

Abstract

Optofluidic manipulation provides a powerful route for guiding micro- and nanoparticles, yet conventional light-induced flow systems often suffer from limited controllability, unstable flow patterns, and poor reconfigurability. Here, we demonstrate programmable optofluidic steering based on multibeam engineering of Marangoni convection technique (MEMCT) around optothermally generated air bubbles. In our MEMCT, focused laser irradiation on a gold film creates localized photothermal heating near an air bubble, thereby reshaping the temperature distribution along the air-water interface. By varying the position, number, and spatial arrangement of laser-induced heat sources, we generate tunable flow patterns ranging from directional transport to complex vortical circulation. Simulations and experiments confirm that these reconfigurable interfacial stress fields can deterministically steer single or multiple particles along prescribed trajectories. Furthermore, by integrating it with microfluidic cross-junctions and extending this strategy to bubble arrays, we realize pump-free, on-demand particle routing. This programmable Marangoni-flow platform offers a simple and versatile strategy for dynamic particle manipulation, with potential applications in lab-on-a-chip systems, micro/nanorobotics, and biophotonic technologies.