Measurement method of particle concentration and acoustic properties in suspension using a focused ultrasonic impulse radiated from a plano-concave transducer

As a method to measure the concentration and property of a particle suspension, we proposed an ultrasonic measurement method using a plano-concave ultrasonic transducer. To carry out the experiment, we used a focused ultrasonic impulse with a broad frequency bandwidth radiated from the transducer, instead of utilizing continuous waves as in the conventional method. By analyzing the frequency components of the echo returned from the reflector put at the focal region of the transducer in suspension, we measured the concentration, etc., from variations of attenuation in the frequency spectrum. As specimens, we used some substances containing fine particles for which the acoustic properties or sizes are heterogeneous to each other. Specifically, the milk fat included in milk was examined in detail to characterize the best-tasting milk. In conclusion, we determined that the particle concentration and acoustic properties were easily and instantaneously measurable using the frequency spectrum obtained from pulse echoes passed through the specimen liquid, and the plano-concave transducer was advantageous in these measurements.