The quadrupole microelectrode design on a multilayer biochip for dielectrophoretic trapping of single cells

This paper introduces a new quadrupole microelectrode design for trapping mass loading of single cells using dielectrophoretic (DEP) force. The DEP force profiles generated by the pattern which represent trapping regions on the biochip platform, were studied using finite element software Comsol Multiphysics v3.5a. Arrays of the quadrupole microelectrode were patterned on a multilayer structure called sandwiched insulator with back contact (SIBC) biochip platform, fabricated using photolithography technique. This platform consists of a 10 nm Nickel-Chromium (NiCr) and 100 nm Gold (Au) top electrode, 5 pm thick SU-8 2005 insulation layer and a bottom layer of 10 nm NiCr and 100 nm Au called the back contact. Access to the back contact is achieved via a microcavity located at the center of the quadrupole microelectrode arrangement. Together, the DEP forces generated from the quadrupole rnicroelectrode and the microcavities are used to anchor single cells and maintain cell positions. The quadrupole design was tested with polystyrene latex microbeads, and Ishikawa cancer cells suspended in media and flowed through microfluidic channels made from PDMS. Single cell trapping becomes evident when both quadrupole microelectrode and back contact are biased using AC potentials of different phases. Experiment results show that the quadrupole microelectrode trapped 22 percent of Ishikawa cancer cells and 17 percent of the polystyrene microbeads. (c) 2012 Elsevier B.V. All rights reserved.