An accurate characterization of pressure driven flow in micro and mini-channels is essential for the design and development of passive-control based microfluidic systems. Polymeric cartridges are especially attractive for this purpose, due to their ease of fabrication and lower cost. The aim of this paper is to experimentally characterize liquid-plug flows in polymeric mini-channels at low velocities (< 2 mm/s) for potential applications in the development of Point-of-Care applications. This paper presents the characterization of the laminar flow behavior of liquid plugs in straight rectangular mini-channels fabricated from four different materials with inner hydraulic diameters ranging from 200 to 350 μm. The mini-channels were fabricated from Poly-Methylmethacrylate (PMMA), Polycarbonate (PC), and Methyl Methacrylate Acrylonitrile-Butadiene Styrene (MABS) using mechanical milling and from Polystyrene (PS) using injection molding All the tests in this study were performed with deionized water (DI) and an external pressure source (syringe pump) was used for actuation. The dynamic contact angles (DCA) of the front and rear menisci of liquid plugs were recorded in real time along with the experimental pressure-drop across the liquid plug(s) (ΔPexp) and the mean flow velocity of the liquid plug (V). The results are compared with a theoretical model which takes into account the surface-tension (capillary) forces and the hydrodynamic (viscous) forces acting on the liquid plug(s). The maximum error-margin between the experimentally measured values of the pressure-drop across the liquid plug (ΔPexp) and the theoretical values (ΔPth), is 13% among all the experiments in this study.

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