C-MEMS based electrodes for the dielectric characterization of microparticles employing dielectrophoresis

Abstract

Dielectrophoresis (DEP), the force experienced by polarizable particles exposed to a nonuniform electrical field, is an electrokinetic technique that has gained importance in the last two decades within the microfluidic research community. DEP can be employed to perform manipulation, isolation, filtration, focusing, characterization, or concentration of microparticles. The efficiency of dielectrophoresis is directly related to the distribution of the electrical field that can be controlled by the geometric design of the electrodes. When information about the dielectric properties of particles is readily available, mathematical modeling can be used to find the desired frequency window before carrying out the experiment, saving time and resources. The dielectric characterization of microparticles employing dielectrophoresis was covered in several works; nonetheless there are some problems yet to be solved. In particular, the uncontrolled distribution of the field nonuniformity within the device was demonstrated to affect the dielectric properties estimation. The geometry of the electrodes defines the dielectrophoretic response of the microparticles under analysis. Carbon MEMS (C-MEMS) is a microfabrication process in which carbon microstructures are obtained through photolithography and pyrolysis of organic precursors. The C-MEMS process is especially useful in biotechnology applications because of the wide electrochemical stability and biocompatibility of carbon. Using C-MEMS process, three-dimensional (3D) electrodes can be fabricated, allowing for the development of new electrode geometries different from the widely used interdigitated fingers and polynomial electrodes. This work deals with the development of 3D electrode geometries employing the CMEMS microfabrication process and construction of microfluidic platforms for the dielectric characterization of microparticles employing DEP. COMSOL Multiphysics was employed to analyze the distribution of the electrical field created by the proposed electrode geometry.