Assembly of acircular SnO₂ rod using optical tweezers and laser curing of metal nanoparticles

Acicular tin dioxide (SnO₂) rods (1-2 mm in diameter, 5-20 mm long) were assembled and fused on the patterned gold electrode by an optical tweezer. In addition, the electrical contact between the assembled SnO ₂ rod and the gold electrode was improved by laser curing of gold nanoparticles and the subsequent sintering in the oven. Here, the nanoparticles covered the entire area of the assembled SnO₂ rod by evaporating a droplet of nanoparticle solution dripped on the assembled SnO₂ rod. Subsequently, nanoparticles near the contact area between the rod and electrode were locally cured by direct heating with a focused infrared laser beam, which induced desorption of the surface monolayer. Therefore, the cured gold nanoparticles could be sintered after the non-laser irradiated nanoparticles were cleaned by the initial solvent application. Without sintering of the nanoparticles, the resistance of the assembled SnO₂ rod was measured over several Mσ. After the nanoparticle sintering it could be reduced to a few hundred kσ, which was in agreement with the resistance of the assembled SnO₂ rod.