Real-Time Visualization of Solutal Marangoni Convection in Sub-100 nm Precursor Films Using Laser-Generated Droplet Probes.

ABSTRACT: We present a tracer-free method for the real-time visualization of flow in nanometer-thick liquid films─an essential scale for controlling wetting and interfacial transport. We demonstrate that focusing a 532 nm continuous-wave laser (≈1 mW) on a bubble region within a 5 μm gap, filled with a binary mixture of liquids with different volatilities and surface tensions (ethanol/PEG-200 mixture), spontaneously generates PEG-rich microdroplets on demand. Here, we show that immediately after the laser is switched off, the droplet depins and travels rectilinearly away from the reservoir at ∼30 μm/s. Coupled laminar-flow/species-transport simulations reveal that the ∼50 nm-thick precursor film sustains a surface flow driven by solutal Marangoni convection arising from spontaneous ethanol evaporati

SUBMITTER: Hakuta S 

PROVIDER: S-EPMC12676736 | biostudies-literature | 2025 Dec

REPOSITORIES: biostudies-literature