Plastic substrates are being investigated for use in microfluidic devices because of their low cost,
ease of fabrication, and wide range of materials properties.  It is well established that the surface
chemistry of a plastic substrate greatly influences the electroosmotic flow (EOF) behavior of
microfluidic channels made from that material.  Typical channel imprinting techniques do not offer
direct control of surface chemistry.  Laser ablation shows promise as a versatile method for directly
forming a variety of microchannel geometries in plastics.  In addition, we have demonstrated that
surface chemistry, and, therefore, EOF behavior can be controlled by changing the atmosphere under
which laser ablation of the plastic is performed.  The surfaces of several plastics ablated in a
variety of environments were studied with x-ray photoelectron spectroscopy (XPS) and attenuated total
reflection infrared spectroscopy (ATR-IR).  The results of this study will be presented and discussed.