Microfluidic devices are usually made by replication with PDMS (polydimethylsiloxane) from masters produced using MEMS microfabrication technology. PDMS is the material of choice for pattern transfer due to its flexibility, chemical stability, and low surface energy.
Creating functional microfluidic devices that integrate manipulation components (i.e., micro-filters or mixers) using MEMS technology is a costly and time consuming operation. This limits the ability to test design variants through agile, rapid prototyping of the device. Direct PDMS fabrication is an attractive alternative which require a direct writing technology. This work demonstrates direct structuring of PDMS with picoseconds pulsed laser, used for rapid creation of a mould for replication of the devices themselves. The main hindrance found in PDMS direct writing is the generation of decomposed layers which limits the further processing and compromises surface quality. The first results demonstrated that a microfluidic device with integrated functional microfeatures can be effectively fabricated without the formation of decomposed PDMS by carefully optimising the laser parameters and machining strategy. Complete 3×3mm microfluidic devices (with the integration of multistage filter components) were thus fabricated in under 2 minutes with lateral resolution down to 10µm.
Hence, an optimized set of parameters allows fast rapid prototyping of microfluidic devices for development and proof of new concepts, using ultrafast lasers.