Sacrificial material assisted laser welding of polymeric microfluidic devices

A critical phase in fabricating microfluidic polymer chips is welding of a cover to a channel in order to produce tube type geometry. A possible method to weld such a cover is by through transmission laser welding of polymer components. The major issue in welding of microstructured parts is blockage of the flow path by molten polymer (flash) resulting from a typical welding process. In this study, a sacrificial material technique is developed, in which a water-soluble material is used as a mold material to prevent weld flash from being allowed to flow into the channels. In detail, a sacrificial mold remains in the embossed parts instead of being separated from the part (De-embossing) after molding. A cover or other embossed part is then welded to this part. In this study, through transmission laser welding was used to fabricate such parts. The sacrificial material was then removed by dissolution in an appropriate solvent. Different mold preparation methods are discussed and examples of welded structures are given here.