Thermocapillary-driven fluid flow within microchannels

TL;DR

This paper presents a novel microfluidic design that uses thermocapillary effects induced by temperature gradients to control fluid flow, demonstrating linear velocity control and potential solar-powered applications.

Contribution

It introduces a biocompatible thermocapillary microchannel design powered by solar irradiation, with experimental and modeling validation of flow control via temperature gradients.

Findings

Fluid velocities of millimeters per second achieved.

Flow velocity is linearly proportional to temperature gradient.

Design enables full control of microchannel fluid flow.

Abstract

Surface tension gradients induce Marangoni flow, which may be exploited for fluid transport. At the micrometer scale, these surface-driven flows can be more significant than those driven by pressure. By introducing fluid-fluid interfaces on the walls of microfluidic channels, we use surface tension gradients to drive bulk fluid flows. The gradients are specifically induced through thermal energy, exploiting the temperature dependence of a fluid-fluid interface to generate thermocapillary flow. In this report, we provide the design concept for a biocompatible, thermocapillary microchannel capable of being powered by solar irradiation. Using temperature gradients on the order of degrees Celsius per centimeter, we achieve fluid velocities on the order of millimeters per second. Following experimental observations, fluid dynamic models, and numerical simulation, we find that the fluid velocity is linearly proportional to the provided temperature gradient, enabling full control of the fluid flow within the microchannels.