3D-printing techniques for low-cost production of microfluidic devices: An experimental study on the design and development of 3D-printed chips for improving mixing process and DNA extraction within microfluidics

Micromixers are one of the most important components in microfluidic devices, which is often required for sample dilution, reagent homogenization, and chemical or biological reactions. Mixing in microfluidic devices, characterized by low Reynolds numbers, is related to the laminar regime of the flow, resulting in a slow process that demands long time and length of the channel for complete mixing. In the past two decades, the vast majority of microfluidic micromixers have been built in polydimethylsiloxane (PDMS) by soft-lithography. The need for accessible and inexpensive microfluidic devices requires new manufacturing methods and materials as a replacement for traditional soft-lithography and PDMS. Recently, with the advent of modern additive manufacturing (AM) techniques, 3D printing has attracted attention for its use in the fabrication of microfluidic devices. The purpose of this study is to introduce an alternative construction for microfluidic micromixers, where the effect of the extruded filaments in the Fused Filament Fabrication (FFF) technique is used to enhance mixing performance within microfluidic micromixers. A simple Y-shaped micromixer was designed and printed using FFF technique. Experimental and numerical studies were conducted to investigate the effect of the extruded filaments on the flow behavior. The experimental results showed that the presence of geometrical features on microchannels, due to the nature of the FFF process, can act as ridges and increase mixing performance similar to slanted groove mixers (SGM) and staggered herringbone mixer (SHM), with the difference that the patterned ridges in FFF method are an inherent property of the process. In comparison to passive and active micromixers, no complexity was added in the fabrication process, and the ridges are an inherent property of the FFF process. The unibody micromixers made through Polyjet, SLA, and FFF platforms are examined and compared in terms of performance and limitations of the different fabrication platforms. The results showed that FFF-printed micromixers have better performance in mixing two fluids at low flow rates. Nucleic acid extraction is one of the essential steps required in the workflow of genetic analyses. In this study, a microfluidic chip is designed and fabricated for lysis and DNA extraction using magnetic beads separation method. The chip design includes three main processes: Lysis, Binding, and Extraction processes.