CFM holey films

Abstract

Chloroform-formvar-mica (CFM) can be used to make holey films in the simplest and most reliable procedure described to date. A wide variety of approaches have been devised to produce thin membranes with holes in them. Hayat (1978) provides an excellent historical overview of these perforated film techniques. They range from complex and cumbersome to relatively simple, but even these simpler techniques require either special solutions or incorporate time-dependent steps which may yield variable results. The CFM technique suffers from neither of these drawbacks; the steps are outlined below.Procedure:l. Dip a freshly cleaved mica strip into a 0.25% solution of formvar in chloroform and withdraw it at a slow, even rate. 2. Wick off excess solution, allow to dry for about one minute, and trim the formvar coated lower edges of the strip with scissors. 3. Score the formvar membrane with a razor blade just below the “high water mark” and float it onto distilled water.