Thickness measurements of lacey carbon films

Lacey carbon filmed grids interact differently with liquid samples during plunging and subsequent studies in cryo-TEM depending on type and manufacture. One important parameter is the thickness of the film, which is investigated here by ultrathin sectioning. The film thickness of the carbon-Formvar type is found to be 100-200 nm, with the variation of the thickness occurring in the polymer layer. The pure carbon type is found to be 20-30 nm thick. Knowing the thickness makes it easier to choose the optimal type for each cryo-TEM sample.