Condensation of fluorescent nanoparticles using a DEP chip with a dot-electrode array

This paper develops a microfluidic chip for programmable condensation of fluorescent-labeled nanoparticles based on dielectrophoretic (DEP) force in order to enhance the strength of fluorescence density in a dot-electrode array. The structure of the DEP chip consists of a top electrode made of indium tin oxide (ITO) glass, a flow chamber formed by optically clear adhesive (OCA) tape, and a bottom 3 x 3 dot-electrode array. The vertically non-uniform electric field can trap nanoparticles on the bottom dot electrode using positive DEP force, and each dot electrode can be individually controlled by a computer-based program for programming manipulations. According to the experimental results, the fluorescence intensity was enhanced about three times when DEP force was applied to condense fluorescent-labeled nanoparticles on the dot-electrode surface. In addition, fluorescence intensity depends on the applied voltage as well as the applied time; an optimal operation parameter of condensation of fluorescent-labeled aluminium oxide (Al2O3) nanoparticles has been proposed based on parametric studies and experimental observations. Consequently, the present study demonstrates that the condensation of nanoparticles on a dot-electrode array using vertical DEP force instead of planar case and programmable manipulation, provides great potential in the application of multi-antibody arrays in a single chip for immunoassays. (c) 2012 Elsevier B.V. All rights reserved.