Abstract
A novel technique of non-instructive microflow control with laser-induced temperature change is described in this paper. In microscale, the scale effect in heat and mass transfer appears and phenomenon is governed by properties of fluids or devices. Generation of local distribution of property have a potential to control flow behavior in microfluids. Absorption of focused laser beam causes local temperature distribution and results in the properties change. We have developed an experimental system to induce local temperature rise in microchannel flow and to measure the velocity profile simultaneously. Velocity measurement is performed by micro-PIV (particle image velocimetry) technique. During the laser irradiation, flow velocity around the hot spot increases by approximately 15%. It is found that the principal factor of the velocity variation of microflow is the temperature dependence of liquid viscosity. Validity of the laser-induced viscosity distribution for liquid flow in microfluidic device is confirmed both experimentally and numerically.
