Device, system and method for emission and reception of ultrasonic signals to and from a test material

Device for emission and reception of ultrasonic signal to and from a test material, the device comprising two or more wheel assemblies attachable to an axle, wherein each wheel assembly comprises:

• an orbital outer ring comprising an inward facing surface;
• a solid or viscoelastic partial or complete inner ring positioned within the orbital outer ring so as to create an interface between the inward facing surface of the orbital outer ring and an outward facing surface of the partial or complete inner ring, the partial or complete inner ring being connectable to the axle in a non-rotating manner and comprising an acoustic impedance in the same order as that of the orbital outer ring;
• one or more transducers fixedly arranged partially or completely embedded, or fixedly attached to the partial or complete inner ring;
• and
• a low friction dry material embedded in at least one of the orbital outer ring or the partial or complete inner ring to decrease movement friction between the outer orbital ring and the partial or complete inner wheel, the low friction dry material having an acoustic impedance in the same order as that of the orbital outer ring;
• wherein the one or more transducers may be oriented and maintained pointing towards the test material as the outer orbital ring rotates relative to the partial or complete inner wheel when moved along the test material.