Optoelectric Trapping and Manipulation of Metal Nanoparticles

Noninvasive particle grippers are highly desired in nanomanufacturing and bio-microfluidics. Rapid Electrokinetic Patterning (REP) provides such functionality by combining AC electric field and laser induced heating on an electrode surface. In this technique, a colloidal solution containing nanoparticles is supplied between two planar transparent indium tin oxide (ITO) electrodes. Application of an AC electric field and the projection of a 1064 nm infrared beam on one of the electrode surfaces results in a toroidal electrothermal vortex which transports particles close to the electrode surface where the particles are reversibly trapped by electrode-particle interactions. We show that the metal nanoparticles such as gold and silver nanospheres (40-200 nm) and multi-wall carbon nanotubes can be trapped and manipulated using this method. We demonstrate application of REP induced aggregation in sensitive chemical detection with Surface Enhanced Raman Spectroscopy (SERS).