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Accueil > Publications > Archives 2004-2010 > 2008

Towards a continuous microfluidic rheometer

P. Guillot-, T. Moulin, M. Guirardel, A. Dodge, M. Joanicot, A. Colin, C.-H. Bruneau, and T. Colin — to appear in Micro & Nanofluidics

publié le

In a previous paper we presented a way to measure the rheological properties of complex
fluids on
a micro fluidic chip ref. The principle of our method is to use parallel
flows between two immiscible fluids as a pressure sensor. In fact, in a such flow, both fluids flow side by side and the size occupied by each fluid stream depends only on both
ow rates and on both viscosities. We use this property
to measure the viscosity of one fluid knowing the viscosity of the other one, both flow rates and the relative size of both streams in a cross section. We showed that using a less viscous fluid as a reference fluid allows to define a mean shear rate with a low standart deviation in the other
fluid. This method allows us to measure the
flow curve of a fluid with less than 250 µ-L of
fluid. In this paper we implement this principle in a fully automated set up which controls the flow rate,
analyzes the picture and calculates the mean shear rate and the viscosity of the studied
fluid. We
present results obtained for Newtonian
fluids and complex
fluids using this set up and we compare
our data with cone and plate rheometer measurements. By adding a mixing stage in the
network we show how this set up can be used to characterize in a continuous way the evolution
of the rheological properties as a function of the formulation composition. We illustrate this by
measuring the rheological curve of four formulations of polyethylene oxide solution with only 1.3
mL of concentrated polyethylene oxide solution. This method could be very useful in screening
processes where the viscosity range and the behavior of the
uid to an applied stress must be