Fabrication of microfluidic devices: improvement of surface quality of CO2 laser machined poly( methylmethacrylate) polymer

Laser engraving has considerable potential for the rapid and cost effective manufacturing of polymeric microfluidic devices. However, fabricated devices are hindered by relatively large surface roughness in the engraved areas, which can perturb smooth fluidic flow and can damage sensitive biological components. This effect is exacerbated when engraving at depths beyond the laser focal range, limiting the production of large aspect ratio devices such as microbioreactors. This work aims to overcome such manufacturing limitations and to realise more reproducible and defect free microfluidic channels and structures. We present a strategy of multiple engraving passes alongside solvent polymer reflow for shallow depth (< 500 mu m) and a layer cutting with laminate bonding for larger depth (> 500 mu m) features. To examine the proposed methodologies, capillary action and bioreactor microfluidic devices were fabricated and evaluated. Results indicate that the multiple engraving technique could reproduce engraved microfluidic channels to depths between 50-470 mu m, both rapidly (6-8 min) and with low average surface roughness (1.5-2.5 mu m). The layer cutting approach was effective at manufacturing microfluidic devices with depths < 500 mu m, rapidly (< 1 min) and with low surface roughness. Ultimately, the proposed methodology is highly beneficial for the rapid development of polymer-based microfluidic devices.