- Tran-Son-Tay, R. and Beaty, B.B. and Acker, D.N. and Hochmuth, R.M., Magnetically driven, acoustically tracked, translating-ball rheometer for small, opaque samples,
Rev. Sci. Instrum. (USA), vol. 59 no. 8
pp. 1399 - 404 [1.1139676] .
(last updated on 2007/04/10)
A new rheometer has been designed to measure the rheological properties at low Reynolds number of microliter quantities of opaque suspensions. The rheometer uses a falling-ball technique to measure steady-state viscosity and a vertically oscillating, magnetically driven ball for viscoelastic measurements. The motion of the ball is tracked by ultrasound echo location in which sound waves are transmitted and received by an ultrasound transducer mounted at the base of the tube. Concentrated suspensions of red blood cells are used as opaque test samples. The results obtained are in good agreement with those reported in the literature. The data confirm the fact that a concentrated suspension of red blood cells behaves as a shear thinning material and that the energy stored by the suspension during an oscillatory cycle increases with frequency. Testing of the rheometer is also made by using a Newtonian silicone oil. Viscosity measurements obtained with both the falling- and oscillating-ball methods are consistent and are within 2% of the value of 47.3±0.5 cP given by the Cannon-Fenske viscometer. However, it is found that the oscillating-ball technique gives the largest standard deviation, 6%, as opposed to 2% for the falling-ball technique
flow measurement;rheology;silicones;ultrasonic applications;viscosity measurement;