Real-Time Ultrasonic-Spectroscopy in Suspensions

A pulse transmission system is described which permits real-time measurements of rapid spectral variations of ultrasonic attenuation in suspensions within a frequency range from 4 to 50 MHz. Results of measurements on suspensions of polystyrene spheres in water are given. Attenuation measurements in human blood show the influence of the fibrinogen concentration and the stirring rate on the aggregation of erythrocytes. The attenuation mechanism (absorption, relaxation and scattering) is discussed in order to obtain a theoretical interpretation of the experimental results. Finally, applications of this method are given.