3D Carbon cages for dielectrophoretic-based bioparticle separation/concentration applications

Abstract

Dielectrophoresis (DEP) is an electrokinetic phenomenon defined as the force experienced by polarizable particles due to their interaction with a spatially-non-uniform electric field. The magnitude and direction of this movement depends upon the interaction between an induced electrical dipole and the electric field, as well as on the relation between the dielectric properties of the particles and the suspending medium in which the particles are immersed. Carbon electrode based DEP (CarbonDEP) is a novel approach to microparticle manipulation. 3D Carbon structures, used here as electrodes for DEP applications, are produced by a sequence of photolithographic patterning and pyrolysis of organic precursors. Carbon has a wider electrochemical stability window than most materials employed in metal-electrode based DEP. Carbon is also biocompatible, making it attractive for biotechnology applications. This work presents new developments in the area of fabrication of CarbonDEP-based microfluidic platforms. Polypyrrole (PPy) posts were fabricated over planar gold leads covered with PPy. The posts were then connected on the top by a layer of laterally grown PPy. PPy cages were tested with polystyrene particles with diameters of 1μm. It was found that PPy cages allow for a higher trapping efficiency compared to planar electrodes and also to flat electrodes with 3D posts. Subsequent pyrolysis step will convert PPy organic precursor into carbon, thus producing Carbon cages. Simulation work was carried out using COMSOL Multiphysics platform to analyze the electric field distribution within a microchannel where DEP particle separation is taking place. Applications of this work include, but are not limited to, environmental monitoring, food safety control, clinical analysis, and clean energy production.