It is also an electroacoustic transducer. It also converts electric power into mechanical energy. Like PET, it can perform the reverse transformation as well. However EMAT can do this without touching the metallic sample. Both PET and EMAT, cause elastic vibrations in a sample by means of a force of action upon its surface.
PET works like a small hammer but through an interim liquid layer rather than directly.
The water ensures mechanical coupling with the sample surface. EMAT actuates electromagnetic forces and therefore does not need any liquid. Lets us try to understand it. Let's first consider the basics of force interaction. The physical basics of non-contact force coupling between EMAT and the controlled object's surface.