All ultrasound devices in the market today use transducers which converts one form of energy to another. Ultrasound transducers specifically create sound waves in the ultrasonic region (sound waves with a frequency higher than 20 kHz) that bounce off the body and soft tissue and produce echoes. These echoes are then received by the transducers as well and go through signal processing which then creates the images that medical professionals look at. These ultrasound devices are highly complicated and require a collaboration between many branches of engineering including mechanical, electrical, acoustics, materials and biomedical.
Current ultrasound technology uses the piezoelectric effect to create transducers. Piezoelectric materials are able to generate electrical signals when a mechanical stress is applied and vice versa. This makes them ideal for ultrasound use as sound waves are mechanical waves, but they need to be converted to electrical signals for imaging use.
Exo, where I worked, takes a different approach to these transducers by using PMUT technology. PMUT stands for piezoelectric micromachined ultrasonic transducers. Piezoelectric materials are still used to generate ultrasound waves to create an image, but on the micro scale instead of the bulk materials used by other companies!
Written by: Athulya Nambiar