Sensorless Blood Viscosity Measurement in a Magnetically-Levitated Centrifugal Blood Pump

Abstract

A sensorless noninvasive method for measuring blood viscosity has been developed for a magnetically-levitated centrifugal blood pump. The blood viscosity can be calculated from the measured phase difference between the input current to the magnetic bearing and the impeller displacement. The experimental results using porcine blood, which has a non-Newtonian property, showed the difference between the viscosity measured by a cylinder viscometer and one by the magnetic bearing was 0.3 mPa·s. In the range of 0.5 to 4.5 L/min, the variation of the measured viscosity was less than 0.2 mPa·s. The results indicate the proposed method can be applied to measure the blood viscosity for clinical use.