A simple technique is described for the formation of microfluidic channels and reservoirs in polymer substrates. The technique is based upon excimer laser mask projection and includes a simple, low cost lift-off procedure, using readily available adhesively backed tapes, for the production of a metallisation layer. An additional advantage of the lift-off technique described is the removal of the debris layer usually associated with excimer laser ablation. The cross sectional profile and texture of the channels have also been controlled.
For the electrokinetic flow device presented here, up to six reservoir structures, including electrode pads, were ablated into polycarbonate, through a sacrificial layer. The entire substrate was then coated with Cu or Au by sputter deposition. Channels, 135μm wide and 135μm deep were engraved into the samples, joining the reservoirs with a selection of "T", "Y" and "X" junctions. The sacrificial layer was then peeled off of the substrate removing both the unwanted metallisation and debris deposited during the ablation process. The channels of the devices were then sealed using a dry film photoresist material which was applied by a simple lamination process. Water was flowed through devices fabricated in this manner by pumping with a syringe and no leakage was observed.