High frequency ultrasonic wave can be used to size particles in liquid and measure their concentration at the same time. The presence of particles in the liquid causes scattering of the ultrasonic wave, this affects the attenuation and velocity of the ultrasonic wave. More particles have more of an effect, so that ultrasounds can be used to assess the particle concentration.
The technique relies on high precision measurement of the speed of sound and attenuation of ultrasounds. It does not require direct contact with the suspension, enabling its use in laboratory as well as in in-line production settings. The measurement is fast, does not require any dilution and delivers results in seconds. This makes it applicable to monitor a wide range of processes, such as grinding, particle growth or settling.
With Ultrasonic Nano Particle Sizing (UNPS), TNO (TNO (the Netherlands Organisation for Applied Technical Research https://www.tno.nl/en/) ) is pushing the boundaries of the method. The use of higher frequencies enables the investigation of nano-particles. The measurement setup is adapted to the requirements of in-line applications. Improved signal processing is designed to take the particle material properties out of the equation.
This enables to measure the particle size distribution, in a fast and reliable way.