Yield stress fluids are versatile materials that flow only when sufficient force is applied to them. They have significant applications in a wide variety of consumer goods (e.g., toothpaste, cosmetics, ketchup) and construction products (e.g., cement). A rheometer is used to measure the viscous flow properties of liquids, but current instrumentation poses several challenges to accurately analyzing yield stress fluids.

A rheometer with a fixed container is used to hold a yield stress fluid for assessment. Unfortunately, the rigid design of containers imparts non-homogeneous flow in the sample during the loading process. Furthermore, the multi-blade geometry of typical 4-arm vane structures causes an uneven stress field on a yield stress fluid. Non-homogeneous flow and uneven stress fields both lead to errors in viscosity measurements. This technology addresses these challenges by redesigning the sample container and vane rotor.