A micromachined polyimide aperture for stable bilayer lipid membrane (BLM)s

Abstract

Summary form only given. Silicon micromachining is used to fabricate reproducible miniature apertures over photosensitive polyimide (PPI) layers (septa), with highly controllable dimensions. PPI, having a high level of planarization, chemical inertness, a low dielectric constant, and good mechanical strength, is a very suitable material to be used as BLM septa. Apertures of approximately 5 mu m thickness and approximately 40 mu m diameter in PPI septa suspended over thick silicon rims were realized. The fabrication process includes double-side oxide growth on the wafer, spin-coating the PPI and its patterning, back surface anisotropic window etching, and a final cleaning step. Apertures with high circular symmetry were fabricated using this process. The BLM is formed by dropping a small amount of phospholipid-alkane solution over the PPI aperture. An initially few- mu m-thick membrane spontaneously thins down to an approximately 50 AA thick BLM. Specific capacitance measurements of these BLMs revealed stability of up to 50 h. >