DIELECTROPHORETIC MANIPULATION OF SILICA NANOPARTICLES IN OPTOFLUIDICS

摘要

We present a dielectrophoretic (DEP) system in microfluidics capable of nanoparticle positioningfor the objective of achieving a dense nanoparticle core and primarily liquid cladding optofluidicsystem. Various DEP conditions were investigated using 450 nm and 230nm diameter silicondioxide (SiO2) nanoparticles at several alternating current (AC) voltage amplitudes, flow rates andfrequencies. Using an array of curved DEP microelectrodes and by utilizing DEP nanoparticlefocusing and repelling capabilities, we were able to form a particle dense stream in the center of themicrofluidic channel. A high refractive index core composed of DEP assembled nanoparticles witha lower index cladding composed of DI water and very low concentrations of particles was formed.By introducing visible light as the excitation source, it was observed that the nanoparticle aggregateeither guides or scatters light. The larger particles tend to scatter light while the smaller particlestend to guide light. The results illustrate a pioneering accomplishment of a configurablenanoparticle-core liquid cladding waveguide that is relevant for optofluidic, lab-on-a-chip andbiosensing applications.