Ultrasonic approach is the option to determine the moisture content of an object when microwave technology is not an alternative. The measurement principle is based on the fact that the propagating velocity of ultrasonic waves through a material depends on the density of the material. In this method, the sensor transmits the ultrasonic wave into the object, and the moisture content is obtained from the received signals.
The primary advantage of the ultrasonic approach is that it is non-destructive. It can provide accurate measurements for a wide range of materials.