My research:
My first two projects were closely related to the ultrasonics.
The nominal human hearing range is 20 Hz to 20 kHz. Ultrasound is thereby defined as sound waves that have frequency beyond 20 kHz, a sound human cannot hear. Ultrasound is the result of mechanical vibrations and requires a medium to propagate. There have been many applications developed in science, industry or medicine utilizing ultrasound.
To generate the ultrasound, two different effects can be used: magnetostriction and piezoelectricity. The argument on the better technology for non-destructive testors to generate the ultrasound between these two has been resolved with the development of the piezoelectric material. With the improvement of the quality of piezoelectric composites over the years, the inherent advantages such as short response time (capable of producing higher frequency signals), lower loss in the system, and ease of customization make the piezoelectric effect preferable in most cases.
