CNC Milling and CO2 Laser Engraving of Mixing Microchannels in Microfluidic Devices

Microfluidic devices play a crucial role in biomedical research, chemical analysis, and diagnostics, with fabrication optimization striking a balance between precision, efficiency, and cost-effectiveness. Currently, there is a need to determine the most suitable fabrication technique for accuracy, efficiency, and material compatibility. This study compared computer numerical control (CNC) milling machines and CO2 laser engraving machines by investigating their strengths and weaknesses as microfluidic device fabrication techniques. Microfluidic devices were designed with mixing microchannels of 1.0 mm width and depth using Autodesk Fusion. Autodesk Fusion was further utilized to configure the drilling and tracing processes of the milling operation, while RDWorks V8 was utilized for laser setup. Three materials with varying chemical resistances, optical properties, mechanical strengths, fabrication feasibility, and cost were selected. Polymethyl methacrylate (PMMA) is cost-effective and optically transparent, polycarbonate offers mechanical robustness and ease of processing, and borosilicate glass possesses outstanding chemical resistance, mechanical strengths, and optical properties. Testing was accomplished through microscopic imaging and colorimetric analysis through a manual pump with a constant downward mass of 461 g. Microchannel precision and fluid flow characteristics determined the effectiveness of each fabrication technique. Based on the food coloring-water mixture mixing capabilities of the manufactured chips, CNC milling presents a significant advantage over laser engraving in channel fabrication due to its ability to produce more consistent microchannels and smoother surfaces. In turn, this results in enhanced fluid flow and mixing efficiency. Polymethyl methacrylate (PMMA) displays the most ideal and cost-effective results through microscopic visualizations and color analysis, with a CNC-milled device being accomplished in 5 min with an overall setup time of approximately 20 min. Thus, making the combination an excellent choice for mass production. This study highlights the significance of utilizing the optimal fabrication technique for microfluidic devices to strike a balance between precision, efficiency, and cost-effectiveness and yield a device that is viable for a broad range of applications from biomedical to chemical fields.