Ultrasonic Transducers and Devices: Design, Fabrication and Applications

Dear Colleagues,

Ultrasonic transducers are frequently used to transform one type of energy into vibrational energy that is categorized by the medium used to generate the waves. These transducers can detect and produce ultrasound energy. A transceiver, receiver, and transmitter are the three main types of these ultrasonic transducers. Piezoelectric materials can generate electrical voltage when mechanical force is applied, which is called the direct effect. These materials also possess the ability to detect ultrasound waves and convert them into electrical energy called the indirect effect. Therefore, piezoelectric materials can be used as a transmitter, or receiver and can combine both effects and be collectively used as a transceiver. Besides piezoelectric transducers, other types of ultrasonic transducers are also used, i.e., electromagnetic acoustic transducers.

In most systems, a transducer produces sound waves within the ultrasonic range, over 18 kHz, by converting electrical energy into sound. After receiving the echo, the resulting sound waves are then converted back into electrical energy, which may be investigated and displayed. It can detect and track the position of different objects. The commonly used types of transducers for the generation and detection of ultrasound are piezoelectric and capacitive transducers. In a capacitive transducer, electrostatic fields are created between a conductive diaphragm and a backing plate. In piezoelectric transducers, the piezoelectric crystal changes its shape and size according to the applied voltage. The area and shape of the active transducer, its ultrasound wavelength, and its ultrasonic velocity in the propagating medium can all affect a transducer's beam pattern.

Rochelle salt, quartz, and several varieties of ceramic are all examples of piezoelectric crystals, which transform an applied oscillating electric field into a mechanical vibration. They are the most commonly used and adaptable type of ultrasonic transducer.

Prof. Dr. Aneela Zameer
Prof. Dr. Muhammad Asif Zahoor Raja
Dr. Ammara Mehmood
Guest Editors

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