Experimental and numerical analysis of microfluids Y-micromixer fabrication using CO2 laser

Abstract

Microfluidic devices (MFD) have several applications in the chemical and biomedical analysis field such as mixing two different drugs prescribed to inpatients. Micromixer can be fabricated using laser beam to ablate microchannel on the surface of polymeric substrate. In this work, CO2 laser was used to manufacture MFD on polymethyl methacrylate substrate with straight and zigzag profiles by investigating the effect of processing parameters (scanning speed, laser power and depth of focus) on the ablated microchannel width, depth, aspect ratio (AR) and wettability. The focus is to produce channel with depths from around 50 µm to 1600 µm using one system, hence producing large microchannels which were not studied in most of the report work. Then a CFD model was developed to characterize the effect of channel geometry and liquid diffusivity and speed on the fluids mixing efficiency. The results showed that the crater width, depth, AR, surface hydrophilicity and surface temperature increased with increasing line energy, and the effect of the process dynamics at constant fluences was also investigated. Various channel profiles such as V-shaped and U-shaped cross sections were produced by shifting the focal position of the beam. This is important in the design phase of the channels, since our single pass method of machining offers a full range of AR from around 0.3 up to 2.25, and a channel depth of 47–1600 µm. The results also showed that the mixing efficiency significantly relies on the channel geometry and fluid flow characteristics, with a maximum mixing efficiency of 99.9% was recorded using a squared shaped MFD.