Flow-assisted Single-beam Optothermal Manipulation of Microparticles

An optothermal tweezer was developed with a single-beam laser at 1550 nm for manipulation of colloidal microparticles. Strong absorption in water can thermally induce a localized flow, which exerts a Stokes' drag on the particles that complements the gradient force. Long-range capturing of 6 mu m polystyrene particles over similar to 176 mu m was observed with a tweezing power of similar to 7 mW. Transportation and levitation, targeted deposition and selective levitation of particles were explored to experimentally demonstrate the versatility of the optothermal tweezer as a multipurpose particle manipulation tool. (C) 2010 Optical Society of America