title: Thin PDMS films using long spin times or tert-butyl alcohol as a solvent.
abstract: Thin polydimethylsiloxane (PDMS) films are frequently used in "lab on a chip" devices as flexible membranes. The common solvent used to dilute the PDMS for thin films is hexane, but hexane can swell the underlying PDMS substrate. A better solvent would be one that dissolves uncured PDMS but doesn't swell the underlying substrate. Here, we present protocols and spin curves for two alternatives to hexane dilution: longer spin times and dilution in tert-butyl alcohol. The thickness of the PDMS membranes under different spin speeds, spin times, and PDMS concentrations was measured using an optical profilometer. The use of tert-butyl alcohol to spin thin PDMS films does not swell the underlying PDMS substrate, and we have used these films to construct multilayer PDMS devices.
authors.affiliation: Department of Electrical Engineering, University of Washington, Seattle, Washington, United States of America. jkoschwanez@cgr.harvard.edu
authors.forename: John H
authors.initials: JH
authors.lastname: Koschwanez
authors.forename: Robert H
authors.initials: RH
authors.lastname: Carlson
authors.forename: Deirdre R
authors.initials: DR
authors.lastname: Meldrum
mesh_terms: D004129:Dimethylpolysiloxanes; D006586:Hexanes; D008567:Membranes, Artificial; D008722:Methods; D012997:Solvents; D020002:tert-Butyl Alcohol
chemical_list: D004129:Dimethylpolysiloxanes; D006586:Hexanes; D008567:Membranes, Artificial; D012997:Solvents; C013830:baysilon; D020002:tert-Butyl Alcohol