Viscosity measurement at ultra-low shear rates using floating electromagnetically spinning system

The electromagnetically spinning viscometer system was improved to measure viscosity at ultra-low shear deformation rates. The system remotely applies driving torque for the rotational-type viscosity measurement through the electromagnetic interaction between the conductive probe rotor and the driving magnets. This allows reduction of the magnitude of the driving torque to approximately 10 −12 N m. The optical lever method is combined with the electromagnetically system to detect rotational angles with a 10 −6 rad resolution. In addition, a cylindrical rotor, sample cell, and positioning apparatus perfectly eliminated the harmful contribution of mechanical friction. Consequently, a viscosity measurement at the shear rates lower than 10 −8 s −1 was proven possible.