Mechanical sound wave which has periodic vibrations and frequencies of more than 20 KHz, which in turn is more than upper human audible range frequency, is known as ultrasound (US) wave (Abu Zidan et al. 2011). It is produced through a transducer that utilizes piezoelectric component or an electromagnetic inductor which has the capability of converting electrical signal into mechanical vibrations and vice versa (Hangiandreou 2003).

The vibration of Fe3O4 nanoparticles in response to an alternating magnetic field can be sensitively detected using contact mode atomic force microscopy (AFM) combined with selective modulation of magnetic domains. While imaging patterned samples of magnetic nanoparticles with contact mode AFM, a magnetic field was applied to drive sample vibration. The field altered in polarity and strength according to parameters of an AC current applied to a solenoid located under the sample. The vibration of Fe3O4 nanoparticles was detected by a nonmagnetic AFM tip to map the changes in frequency and amplitude of the vibrating sample at the level of individual Fe3O4 nanoparticles and clusters.