Plasma processing has been developed to produce selective chemistry in the inner surface of a microfluidic system. This dry process is an alternative solution to the Chemical Vapor Deposition (CVD) process that allows us to work at low temperatures thus avoiding the degradation of the substrate by heat. The present study focused on the surface modification of PDMS in order to make them more hydrophilic and capable to exhibit a high percentage of COOH functions which will provide a good asset for future cell attachment.