Non Newtonian capillary flow in a closed microchannel: towards a disposable single chip blood viscometer

N. MORHELL; H. PASTORIZA

Twente

Conferencia; 1st International Conference on Micro and Nanofluidics. Fundamentals and applications; 2014

University of Twente

In this work we present the design of a microstructured viscometer for complex fluids, such as blood, featuring measurements with a single drop of fluid (~50 µL). Rheometry is based on the dynamics of capillary viscometer, where the velocity and position of a fluid drop entering a microchannel depends only on the channel dimensions, capillary pressure and fluid viscosity. The trasient analysis of the fluid entering a single closed ended channel allows to unbind capillary pressure from viscosity parameters, while channel geometry is independently measured by optical profilemetry and SEM imaging. To describe the rheometry of a non newtonian fluid, a power law constitutive equation is proposed. We discuss how is it possible to measure power law fluid as we derive an equation of the pipe flow in microchannels. The device was successfully tested with human whole blood and with a commercial wood varnish.