關鍵字：明膠，鹽析，碎形微圖案，重鉻酸鉀，聚二甲基矽氧烷。 Bio-compatibility is the one of the most primary concerns in biomedical fields. Gelatin is extracted from skins and bones of animals, satisfies the requirement of compatibility and is a good material to bio application. The prior art of gelatin machining uses photo-lithography to transfer micro patterns of the photomask to gelatin surfaces through ultra-violet light exposing and cross linking. The appropriate pattern design and the confirmation of toxic residuals are the two main technical issues. In this study, we proposed developing a novel gelatin micromachining technique which focuses on solving the first issue for gelatin micro patterns applied to stem cell culture with fractal dendrite configuration. Such a chaotic tree-like fractal patterns have been verified through precipitating among the gelatin film matrix which is spun coating on a glass substrate at the room temperature. The weight percentage of the gelatin matrix is over-saturated. As the temperature decrease, the gelatine will crystallize and to form a natural fractal pattern. The minimum line width of the fractal patterns ranges from 10 to 100 micro-meter, and the height from 5 to 10 micron-meter. To solve the problem of toxic residuals, inorganic salt is used herein to replace the potassium dichromate and to create natural fractal micro patterns in gelatin. The feature size of the fractal pattern is then matching the scales of living cells or the herringbone ribs of the conventional chaotic micromixers, therefore we have the chance to fabricate a new cell culture substrate with bio-compatible manner or a new chaotic mixers embedded with the fractal patterns inside.
