Fabrication of microfluidic networks with integrated electrodes

In this paper a method is presented for the fabrication of micro-channel networks in glass with integrated and insulated gate electrodes to control the zeta-potential at the insulator surface and therewith the electro-osmotic flow (EOF). The fabrication of the electrodes is a sequence of photolithography, etching and thin film deposition steps on a glass substrate, followed by chemical mechanical polishing (CMP) and subsequently direct thermal bonding to a second glass plate to form closed micro-channels. Plasma enhanced chemical vapor deposition (PECVD) $SiO_2$ layers as insulating material between the electrodes and micro-channels and different electrode materials are examined with respect to a high bonding temperature to obtain an optimal insulating result. A CMP process for the reduction of the $SiO_2$ topography and roughness is studied and optimized in order to obtain a surface that is smooth enough to be directly bondable to a second glass plate.