A tunable microfluidic-based filter modulated by pneumatic pressure for separation of blood cells

Abstract

This article presents a new microfluidic-based filter for the separation of microbeads or blood cells with a high filtration rate. The device was composed of a circular micropump for automatic liquid transport, and a normally closed valve located at the filter zone for separation of beads or cells. The filtration mechanism was based on the tunable deformation of polydimethylsiloxane (PDMS) membranes that defined the gap between a floating block structure and the substrate which determined the maximum diameter of the beads/cells that can pass through the filter. Another unique feature of this filter is an unclogging mechanism using a suction force, resulting in a back flow to remove any trapped beads/cells in the filter zone when the PDMS membrane was restored to its initial state. The separation performance of the proposed device was first experimentally evaluated by using microbeads. The results showed that this device was capable of providing size-tunable filtration with a high recovery efficiency (95.25–96.21%) for microbeads with sizes smaller than the defined gap in the filter zone. Furthermore, the proposed device was also capable of performing separation of blood cells and blood plasma from human whole blood. Experimental results showed that an optimum filtration rate of 21.40 and 3.00 μl/min correspond to high recovery efficiencies of 86.69 and 80.66%, respectively, for red blood cells (RBCs) and blood plasma. The separation method developed in this work could be used for various point-of-care diagnostic applications involving separation of plasma and blood cells.