A technique is presented for fabricating microchannels for flow investigation with fluorescent particles. The channels were fabricated using plasma etching of a thermoset polymer film, UV15 from Master Bond. The UV15 was spun on a silicon wafer to give a depth of 100μm. A 100nm thick patterned aluminium film was sputtered and patterned on the polymer surface for the etch pattern mask. Sputtering conditions were optimised to prevent damage to the polymer layer. Etch depths to 100μm were obtained. Curing conditions were optimised to prevent wrinkling of the Al/polymer surface during etching. There is a wide variation in the polymer etch rate which can be attributed to many factors. However, one of the most significant is the energy dose (mW/cm2) to cure the polymer. For etch depths greater than 20μm the channels varied from the rectangular cross section shape by undercutting on the walls and deeper etching at the bottom of the channel walls. Conditions for obtaining uniform microchannels for 100μm wide and 50μm deep channels, 5cm long are presented.