A novel type of spiral micromixer with expansion and contraction parts is presented in order to enhance the mixing quality in the low Reynolds number regimes for point-of-care tests (POCT). Three classes of micromixers with different numbers of loops and modified geometries were studied. Numerical simulation was performed to study the flow behavior and mixing performance solving the steady-state Navier–Stokes and the convection-diffusion equations in the Reynolds range of 0.1–10.0. Comparisons between the mixers with and without expansion parts were made to illustrate the effect of disturbing the streamlines on the mixing performance. Image analysis of the mixing results from fabricated micromixers was used to verify the results of the simulations. Since the proposed mixer provides up to 92% of homogeneity at Re 1.0, generating 442 Pa of pressure drop, this mixer makes a suitable candidate for research in the POCT field.

A passive portable microfluidic blood–plasma separator for simultaneous determination of direct and indirect ABO/Rh blood typing.

Blood plasma separation from undiluted blood is an essential step in many diagnostic procedures. This study focuses on the numerical optimization of the microfluidic blood plasma separator (BPS) and experimental validation of the results to achieve portable blood plasma separation with high purity and reasonable yield. The proposed design has two parts: a microchannel for blood processing and a tank, below the aforementioned main channel, for plasma collection. The study uses 3D computational fluid dynamic analysis to investigate the optimal ratio of heights between the top microchannel and the tank and their geometry at various flow rates. Thereafter, the results are compared with the experimental findings of the fabricated devices. These results are put in contrast with some recent reported works to verify the proposed device's contribution to the improvement of quality and quantity of the extracted plasma. The optimized design is capable to achieve a 19% yield with a purity of 77.1% and depending on the requirement of the point-of-care (POC) application. These amounts could be tuned for instance to 100% pure plasma, but the yield would decrease to 9%. In this study the candidate application is hemostasis, therefore, the BPS is integrated to a biomimetic surface for hemostasis evaluation near the patients.Received: ((will be filled in by the editorial staff)) Revised: ((will be filled in by the editorial staff))

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