Flow channel geometry can be varied to produce different types of continuous deformation. VROC® microfluidic flow channels are available with either a uniform cross-section for steady shear viscosity measurement or a centrally located hyperbolic contraction-expansion for extensional viscosity estimation. Changing the geometry of the microfluidic flow channel can introduce an extensional component to the deformation. Simple and complex fluids are both known to respond differently to steady shear versus extensional.
In this application note, we measure xanthan gum solutions at several concentrations in both types of channels to illustrate the change in material response with deformation.