Figure 4: Durability of the infrared absorption film as a plasma-shielding mask. (a) Initial phase-contrast images of a rectangular microhole created in a film (left) and a resulting cell colony formed within the “minus”-shaped microdomain (right). (b, c) The same mask as of that in (a) but after 11 (b) or 18 (c) times repeated use (left). Cells faithfully adhere to the specific area (right), thus showing the repeatable use of the identical mask. (d) Widths of cell colonies (Cells) and microholes (Film) after 1,11 and 18 times use, represented by mean ± SD (n=6). (e) Width ratio of cell colony to microhole, represented by mean ± SD (n=6). Scale bar, 200 μm.