On the behavior of non-Newtonian fluids in microsystems for biotechnology
J. Berthier, S. Le Vot, P. Tiquet, F. Rivera, P. Caillat
Cea-Leti Minatec, FR
Keywords: non-Newtonian fluids, shear thinning, constriction, microfluidic networks, flow focusing devices
Abstract:In Biotechnology, it is generally the use to calculate and design prototypes of microsystems by considering aqueous or organic liquids that have a spatially uniform viscosity. However, many liquids used in biological applications are at least slightly or moderately viscoelastic; their viscosity decreases with the shear rate exerted by the flow field. This is the case of blood, sweat and tears, and polymeric liquids—like alginate or polysaccharide solutions. At first sight, it is tempting to neglect the viscoelastic effect assuming it is of second order; however, we show here that this is not always the case as soon as the solutions are semi-dilute. In this work, we analyze briefly the rheology of polymeric solutions and we show the implications of their viscoelastic behavior on the flow field in capillary ducts, constrictions, microfluidic networks, recirculation regions and flow focusing devices.