Characterization of Silicon-Based Insulated Channels for Capillary Electrophoresis

A new fabrication method to produce miniaturized Transparent Insulating Channels (μTICs) is presented. The process involves Deep Reactive Ion Etching (DRIE), insulating film deposition, anodic bonding and back etching of the silicon. The μTIC process leaves optically transparent channels that can be cooled very easily due to the thin walls, thus in principle enabling higher electric field strengths. Because the fragile nature of thin walls limits the practical application of the μTICs, a polymer film is added to reinforce the microstructures. A μTIC design with an injection- and separation channel and containing a 100 μm long injection loop is realized and evaluated. EOF was confirmed by the use of fluorescently labeled, 3 μm diameter beads observed by a CCD camera coupled to a fluorescence microscope. Current/voltage curves were linear up to applied fields of 700 V/cm. For the first time, siliconbased microchannels have been realized that are suitable for CE. Thus, μTICs allow for high flexibility in the design of insulated channels with respect to dimensions and cross-sectional shapes for analytical techniques where insulating materials are required, such as CE.