The effect of particle seeding on the rheological properties of blood Analog fluid used during laser Doppler velocimetry

BackgroundThe viscosity of blood analog fluid (BAF) influences the hemodynamics during testing of medical devices and implants in cardiovascular systems mimicking physiologic flow conditions. BAF, typically composed of water, glycerin, and Xanthan gum, is used to simulate blood's non-Newtonian shear-thinning behavior. Additionally, BAF may include microsphere particles for flow visualization in Laser Doppler Velocimetry (LDV) experiments, though their impact on viscosity remained an under-investigated area. Hypothesis: Addition of particles in the form of polymer microspheres in a BAF solution influences the rheological properties of the fluid.MethodsThree different test fluids comprising of 16 ml BAF solution with the varying concentrations of polymer microspheres were created: 1% (weight/volume; w/v) and 2% w/v represent test samples, whereas 0% w/v (no microsphere) represents a control sample. The viscosities of BAF for with and without polymer microspheres were measured using a concentric cylinder viscometer. Recorded viscosity data was then optimized by fitting the Carreau model.ResultsSeeding of polymer microspheres in BAF results in significant changes in shear-thinning properties, such as zero- and infinite-viscosity (μ0 and μ∞, respectively), in relation to viscosity of real blood or BAF without microspheres. It is evident that effect of microsphere seeding in BAF is relatively more pronounced on μ0 as compared to μ∞.ConclusionPolymer microspheres in BAF significantly alters its shear-thinning properties and must be considered for better hemodynamic evaluations in medical device testing.