Electromagnetically Spinning Sphere Viscometer

Abstract

We have developed a simple system for viscosity measurement in the range of 10-3 to 101 Pa·s. An aluminum sphere revolves in a sample cell under a rotating external magnetic field, and the rotational speed of the sphere gives the sample viscosity. Low viscosities can be measured by using a micro-probe sphere, since the viscous torque applied to the sphere overcomes the frictional force at a sufficiently small sphere radius. The system is free from contamination and can be easily applied to medical and biological studies.

Increased Blood Viscosity in Ischemic Stroke Patients with Small Artery Occlusion Measured by an Electromagnetic Spinning Sphere Viscometer

“…A newly developed electromagnetic spinning sphere (EMS) viscometer has the ability to measure a small amount of samples quickly and sequentially in a non-contact disposable manner and skips the time-consuming washing process after each sample measurement. [20][21] We previously introduced the measurement of blood viscosity with the EMS viscometer and reported our findings on control volunteers. 22 In the present study, we measured blood viscosity in acute ischemic stroke patients and discussed the importance of blood viscosity measurements in terms of differential diagnoses and the treatment of ischemic stroke.…”

Thermally reversible cross-links in a healable polymer: Estimating the quantity, rate of formation, and effect on viscosity

“…The relationship between torque and angular speed is related to the viscosity of the fluid. Rotational viscometers include the cup and bob, cone and plate, and electromagnetically spinning sphere types [25]. Plaisted [15] used a cone and plate viscometer to estimate the initial viscosity of 2MEP4FS prepolymer as 0.112 Pa·s (112 cP) at 90 °C.…”

“…The electromagnetically spinning sphere approach is possible but limited to 10 Pa·s [25], which is too low for the present materials at room temperature. Effectively transferring this small quantity of prepolymer to a cone and plate-type viscometer would be challenging.…”

Torsional oscillations of a sphere in a Stokes flow

“…This enables the measurement of the rheological properties of micro-to pico-litre volumes of viscous fluids [23] and in vivo testing [32]. Furthermore, non-mechanical control is essential in such viscometers, as the friction between the rotational axis of the sphere and the mechanical support often restricts the lower limit of viscosity measurement [22].…”