Filling phenomena in microfluidics and front microrheology of biological fluids

In this work we present a method, based on the functioning of microrheometry, which is capable to determine the viscosity of a fluid using the fluid-air interface dynamics driven by hydrostatic pressure, inside a rectangular microchannel. First, we worked at a constant velocity regime, where the viscosity of four Newtonian fluids were characterised: water, ethylene-glycol, 50% glycerol and blood plasma. Then, we applied this method to blood samples of 45% and 35% haematocrit, at the same velocity regime and we were capable to calculate the viscosity of these samples. Moreover the method was able to distinguish blood concentrations with different haematocrits.