Abstract
Thermophoresis is the motion of micro/nanoparticles induced by the temperature gradient of fluids. In the present paper, we successfully apply the thermophoretic phenomena to the filtration technique of microparticles in a microfluidic device. A local temperature increase in a microchannel is produced by irradiating the near-infrared laser and the radial temperature profile is measured by the laser-induced florescence. The laser is moderately focused at the inlet of contraction in the microchannel. Since the microparticles are repelled from the hot region, they hardly approach the inlet of contraction. As the result, only the solution passes through the contraction.
