MEMS Stabilized Lipid Membranes and Their Parylene Encapsulation

Planar lipid membranes composed of egg phosphatidylcholine and 1, 2-dioleoyl-sn-glycero-3-phosphocholine were suspended over arrays of 100, 75, and 30 mu m diameter holes in a 3.7-mm-thick polyimide or 2-mu m-thick Parylene film that was supported on a silicon frame. Membranes were allowed to thin in buffer and periodically examined in air with reflected light microscopy. Once the membranes approached the thickness of a bilayer, they were vapor coated with 80 nm of conformal Parylene. The Parylene coating essentially fixed the membranes indefinitely for further study via optical microscopy, scanning electron microscopy, energy dispersive x-ray spectroscopy, atomic force microscopy, white-light interferometry, and confocal microscopy. This paper demonstrated that lipid membranes suspended on microfabricated hole arrays lasted over six days in buffer and that thinning membranes go through a phase where the lipids form lamellar stacks of bilayers within the holes. A technique for encapsulating the suspended membranes in Parylene was demonstrated that enabled detailed measurements of membrane geometry and composition. [2016-0227]