Droplet trajectory control using repusive thermocapillary effects in a microchannel

Abstract

Droplet control using thermocapillary effects is paid attention for strong driving force compared to optical tweezer. Thermocapillary effects occur when the interfacial tension gradient is induced by the variation of temperature. Unlike previous studies, we investigated repulsive thermocapillary effects on a droplet trajectory by illuminating a continuous phase with a laser beam. As a result, we found that the trajectory shifting increases with increasing the laser power or the droplet diameter. We successfully routed droplets toward one of three outlets at higher than 95 % success rate on demand by using repulsive thermocapillary effects.