Interfacial Flows and Interfacial Shape Modulation Controlled by the Thermal Action of Light Energy

Abstract

The review covers the research on thermocapillary convection caused by the thermal action of laser radiation in single-layer and bilayer liquid systems of capillary thickness. The advantages of using optical radiation are the instantaneous delivery of thermal energy to a place on demand (a bulk phase, interfaces); low radiation power required; concentrating heat flux on a spot of a few micrometers; the production of arbitrary spatial distributions of radiation intensity; and, as a result, corresponding thermal fields at a liquid interface and their fast reconfiguration. Thermocapillary stresses at the liquid interfaces lead to the transfer of the liquid and a change in the shape of the interface, in accordance with the distribution of the light-induced thermal field. Studies concerned with the methods of non-destructive testing of liquid media and solids, which are based on a photothermocapillary signal emitted by a laser-induced concave deformation of a thin layer, are considered. Features of thermocapillary deformation of a liquid–air interface caused by local heating of thin and thick (exceeding the capillary length) layers are demonstrated. A part of the review addresses the results of the study of thermocapillary rupture of films in the heating zone and the application of this effect in semiconductor electronics and high-resolution lithography. The works on the light-induced thermocapillary effect in bilayer (multilayer) liquid systems are analyzed, including early works on image recording liquid layer systems, liquid IR transducers, and nonlinear optical media.

Controlling Spatial Morphology of Microparticle Deposits via Thermocapillary Flows: Effect of Boundary Geometry

“…As a result, the liquid layer near the heater thins until the onset of particle transport by the bottom current, which occurs when the temperature gradient satisfies the condition of eq . Experiments , have shown that, at a fixed temperature difference or heat source power, the depth of the thermocapillary cavity, Δ h , in the center increases with decreasing the initial thickness of layer. Thus, in a thin layer, the cavity depth will be significant.…”

Light Fueled High-Throughput Binary Droplet Splitting and Transport on High-Energy Substrate

“…The fluid then flew outward along the interface from the high-temperature region with respect to the laser-acted zone to the low-temperature region. An inward flow inside the droplet arose from the colder region due to mass conservation, forming a complete circulation loop. − Actually, this circular flow could be stable in the case of low laser power (38 mW), which was characterized by adding polystyrene (PS) tracer microspheres into the droplet to probe Marangoni convection. There was a stable Marangoni flow and no deformation of droplet interface (Movie S2).…”