Fabrication of 3D microfluidic structure with direct selective laser baking of PDMS

Purpose The purpose of this paper is to present three-dimensional (3D) printing of structures with a new method called selective laser baking (SLB) of Poly Dimethyl Siloxane (PDMS). Design/methodology/approach A 3D model is designed on the computer. PDMS Base is mixed with its hardener and poured into a container. Before it is hardened which normally occures after several hours, a CO2 laser selectively exposes different areas on the surface of the PDMS mixture according to the pattern of a slice of a 3D model designed on the computer. Because of the thermal effect of the CO2 laser, once exposed, PDMS heats up and hardens, producing a cured layer of PDMS which is attached to a base. The base with the cured layer is lowered in the container for a short distance and a layer of new uncured PDMS is spread over the previous layer. The laser exposes new areas again and hardens them. This process is repeated until the whole structure is fabricated. Findings The parameters involved in the baking process are investigated and the relation between temperature, mixing portion and laser irradiance on the curing time and layer thickness are investigated. Originality/value This fabrication technique is a unique fabrication method that helps to 3D print with two base polymers which their polymerization can be boosted by heat. This 3D printing method has not been presented earlier.