Engineering the retention of coloured latex and red blood cells for paper agglutination diagnostics

The effective pore cut-off size of the designed diagnostic papers was found to be 20 μm. Size exclusion is not the dominant retention mechanism in paper filtration processes for the smaller colloids (0.5 μm) for Whatman and diagnostic papers. The retention efficiency of polystyrene beads measured on diagnostic papers increased linearly with particle size with saturation effect for the larger particles. Red blood cells (RBC) have a much lower retention efficiency than the equivalent 8 μm beads, highlighting the important effects of particle elasticity and shape.