Automatic Flow Analysis for Human Blood at Low Shear Rate Range

A compact-sized falling needle rheometer with quick operation and automatic flow analysis has been developed for viscometry of human blood. The volume of a sample of blood only needs to be 4 mL and the measuring time is within 3 min. Measured flow properties of blood are evaluated as a flow curve showing the relationship between the shear stress and shear rate. Observed flow curves of the human bloods show three typical fluid regions, these are, the Non-newtonian fluid region for a low shear rate range, the transition region and the Newtonian fluid region for a high shear rate range. In normal male blood, the whole blood viscosity was 9.43mPa·s in the shear rate of 25 s -1 , 5.90mPa·s in the shear rate of 250 s -1 , and 5.77mPa·s in the shear rate of 500 s -1 (310K). The anticoagulated blood viscosity was 8.48mPa·s in the shear rate of 25 s -1 , 5.37mPa·s in the shear rate of 250 s -1 , and 5.21mPa·s in the shear rate of 500 s -1 (310K). These anticoagulated blood values were within the range of blood viscosity reported by other investigators. These show the shear rate dependency. More studies will be necessary to further explore these findings.