Electric field driven extensional rheometry of synovial fluid

The response to extensional deformation of aqueous polymeric solutions depends strongly on the molecular weight and concentration of the solute. The molecular weight of hyaluronic acid in the synovial fluid is a critical parameter for its physiological condition. We propose a novel method for the characterization of these kinds of fluids using a fluidic two-phase system where a dispensed droplet is elongated by electrostatic forces from a voltage source of up to two kilovolts. This way a filament is formed comparable to laboratory capillary breakup extensional rheometers. High-speed imaging is used to investigate the rapid deformation process. Using a mathematical model for the dynamics of the filament evolution, the fluid parameters like the shear viscosity and elastic modulus are derived. The deformation rate can be controlled over a wide range by the magnitude and slope of the applied voltage.