In this paper, an analytical modeling of microchannel design and manufacturing with excimer laser micromachining is presented for medical devices development. Micro/Nano fabrication methods have made possible the creation of extremely tiny structures and systems which cannot be generated using traditional manufacturing processes. Current fabrication methods of microchannels generally require serial fabrication processes including a masking process. To overcome the drawbacks of current methods, we propose to use excimer laser micromachining to directly create microfluidic structures. Parametric study of laser machining was conducted before fabrication of microfluidic systems on polyethylene. An analytic modeling of the laser micromachining is presented to predict the machined microstructures and the surface finish. The liquid flow was visualized and studied using fluorescent dye and the velocity was measured to compare liquid behavior in each channel. The presented techniques can be used for the design and manufacturing of micro-scale medical devices development.