Manipulation of mica flakes using photothermally generated microbubbles

Abstract

We experimentally investigated the manipulation of mica flakes using photothermally induced microbubbles. Iron silicide was sputtered on mica flakes to absorb the laser light and convert it to heat. By focusing a laser on to the flake immersed in degassed water, a water vapor microbubble was generated on the flake. The bubble involved strong Marangoni flow due to the steep temperature gradient on it. Laser irradiation at multiple spots allowed us to control the direction of the temperature gradient and subsequent Marangoni flow. By generating the flow parallel to the flake surface, the flake was driven on the glass substrate. This method is expected as a novel method to manipulate large and heavy particles in microfluidic channels.