Photomodification of polymer microchannels induced by static and dynamic excimer ablation: Effect on the electroosmotic flow

This paper presents a study of polymer surfaces modified by laser ablation using poly(ethylene terephthalate) (PET) as a model system. The surface pro perties induced by static and dynamic ablation with the 193-nm pulsed radia tion of an ArF excimer laser (4 x 10(7) W/cm(2)) in air have been successfu lly used to control the electroosmotic flow (EOF) in photoablated PET micro channels. Through the creation of well-defined static ablation patterns ont o the walls of a trapezoidal channel, it was found that the resulting reduc tion in the EOF could be controlled. For example, a reduction of 25% in the EOF was observed in 42-mum-deep microchannels when using a static ablation pattern treating 50% of the total wall surface area. A numerical study des cribing the fluidic behavior induced by a static pattern is also presented. Moreover, X-ray photoelectron spectroscopy has been used to point out surf ace changes between static and dynamic ablation, thereby demonstrating an a bility to create new functionalities in microchannels by laser treatment.