New method for rapid fabricating masters of PDMS-based microfluidic devices

A new method for rapid fabricating masters of PDMS (polydimethylsiloxane)-based microfluidic devices is presented and the corresponding process is studied. Liquid phase photoresist is adopted as the material of masters, which can be cured to form microstructures by UV exposure under liquid phase. Baking liquid phase photoresist is eliminated during fabricating process. Compared with the current methods that mostly use SU-8 photoresist as the masters material, the method presented can not only simplify the fabricating process but also shorten the fabricating time sharply and avoid distortion caused by the baked internal stress, which doesn't need expensive equipment and can reduce the material cost. The experimental results show that the masters microstructures have the characteristics of nearly vertical sidewalls and smooth surfaces, whose maximum aspect ratio can reach 5.7. The PDMS microstructures replicated demonstrate a desirable precision in shape and dimension.