Abstract: The invention concerns a measuring apparatus for checking and determining the flow shear stress of certain suspensions, principally blood, by a static or dynamic method and to thereby plot the viscosity of the suspension. The apparatus employs an internal measuring chamber comprised of a passage arrangement to simulate the natural microcirculation area wherein a network of capillary passages diverge from a main passage, with at least two of the capillary passages of different lengths, with a length ratio that can range from 3:1 to 15:1, with those capillaries connected to a source of variable pressure and extending past a detector unit.