Measurement of ultra-low viscosity under steady shear flow by suspended EMS system with automatic rotation tracker

Abstract An accurate viscosity measurement system was developed by enhancing the viscometer driven by the suspended-type electromagnetic spinning method. In a previous study, a rotation probe for detecting viscous torque was suspended from a thin wire to maintain its position and orientation within the sample. The probe could rotate without experiencing any mechanical friction; however, its rotation was limited to an angular range where the restoring torque induced by wire distortion remained safely smaller than the viscous torque. To overcome this limitation, the supporting wire was rotated using an additional upper motor, enabling the continuous and steady rotation of the probe. The viscosities of pure water and aqueous solutions of sucrose at shear rates lower than 1 s −1 were successfully measured.