Microfabricated porous glass channels for electrokinetic separation devices

Abstract

Electrically insulated porous SiO₂ channels for electrokinetic separation devices were fabricated based on a mask-less etching process for creation of high aspect ratio needles in silicon. The silicon needles are converted to SiO₂ by oxidation and integrated within the interior of a fluidic channel network. The channels are about 5 µm high with a pore size of 0.5 ± 0.2 µm. An electrophoretic separation of a mixture of fluorescein and 5-carboxyfluorescein using epi-fluorescence detection was performed to verify proper electrokinetic transport in the porous channels. The plate height was about 170 000 m⁻¹ for a field strength of 170 V cm⁻¹. In the near future, it is intended to extend the fabrication scheme to include an array of porous pillars for capillary electrochromatography experiments.