A passive two-way microfluidic device for low volume blood-plasma separation

Blood-plasma separation is one of the main concerns for Point-of-Care devices seeking to retain cells of interest or analyze plasma biomarkers. The present work describes a novel passive device based on size-exclusion method. Starting from a particulate-trap-like filter, numerical simulations in ANSYS Fluent were performed in order to optimize the geometry for blood-plasma separation. The final layout was then embedded inside a microfluidic channel and the related master produced with standard cleanroom processes. A 1 mm thick Cyclic Olefin Copolymer wafer was chosen for hot embossing replication, since Cyclic Olefin Copolymer is a transparent, solvent-resistant and medical-grade material. Moreover, the adopted process is easily scalable to industrial levels. The filtering efficiency was finally assessed with a 4 mu m fluorescent beads dispersion, mimicking the erythrocytes average diameter of 8 mu m. No fluorescent particles were observed downstream of the filter after filtration, thus all the beads were retained by the optimized filtering structure.