In this paper we present an approach towards a biosensor based on the gating action of ion channel proteins integrated on a silicon chip using planar microfabrication technology. The ion channels are inserted into lipid bilayer membranes which are supported across apertures in the wafer. The use of deep silicon reactive ion etching allows fast and exible fabrication of these apertures in the range of 150 μm diameter with the potential for future downscaling. A plasma-deposited surface modi cation layer was introduced to increase the hydrophobicity of the sample and allow reproducible bilayer formation with gigaohm seal resistances. Studies on patterned planar Ag/AgCl electrodes show a good longterm stability of the Nernst potential and an easy integration with the microfabricated aperture.