Ultrasonic Piezo Transducers & Ultrasound Transmitters

Vibratory ultrasonic piezoelectric transducers have the capacity to operate at extremely high frequencies, allowing them to be used in a wide range of ultrasonic applications. Ultrasonic vibration in piezoelectric sensors and piezoelectric transducers are generated by converting an electrical charge (AC voltage) into a vibration movement at ultrasonic frequencies. The intense vibrational movement can be harnessed in piezoelectric ultrasound transmitters and ultrasound transducers to perform various tasks. The most common types of ultrasound transducers and ultrasound transmitters in piezo applications include motors, imaging, cleaning devices, and various sensors. Here, we will discuss ultrasonic piezoelectric transducers used in motor and cleaning tools.

Ultrasonic piezo
Ultrasonic piezoelectric transducers are commonly used for their powerful vibration effects.

Types of Motors and Basic Mechanics

We will discuss two types of motors: linear and rotary. Both types utilize a repetitive motion generating small movements. The simplicity and high frequency capability of ultrasonic transducers are often a perfect solution for these applications requiring minimal movement.

Piezoelectric crystals can be applied in two ways: they can either be used to generate the movement, or to generate friction. The latter type uses locking mechanisms, where the crystal can either be locked or free (to or from the surface being traversed). A crystal becomes locked by expanding and creating frictional force with the surface. Conversely, it becomes free by contracting and moving out of contact with the surface. This crystal generating movement utilizes the frictional force and expands to move across the surface.

Three Piece Motors

The most common type of motor (both linear and rotary) uses one rectangular piezoelectric crystal to generate movement and two piezoelectric crystals on either end to generate friction. When expanding, one crystal locks while the other frees up, causing the motor to generate motion away from the locked crystal. Once the center piece is fully expanded, the first locking crystal frees up while the other locks onto the surface. When the center piece contracts, a force is, again, exerted away from the first piece.

One variation of such a motor is where one piece is always free and the other is always locked. The center piece expands slowly so the free piece is pushed outwards. It then contracts rapidly, generating enough force for the locked piece to slip towards the free piece slightly.

Ultrasound Transmitters and Ultrasonic Imaging

Ultrasonic transducers consist of piezoelectric crystals that emit and receive high-frequency sound waves by converting electrical and mechanical energy. In diagnostic and imaging ultrasound systems, the ultrasound transmitter emits sound waves that are directed into the body and reflected back to the ultrasound transducer. The reflected sound waves are received by the ultrasonic transducer and translated into electrical signals used for image generation. The frequency of the sound waves delivered by the ultrasonic transmitter determines the image resolution and depth of field visualized. The speed and absorption of the transmitted signal in the tissue, and the reflection of the sound wave back to the piezo transducer from the tissue, constitutes the ultrasonic properties of a structure. The correspondence between the ultrasound transmitter and receiver creates the ultrasonic image. 

Cleaning Mechanics

One of the most common commercial applications for ultrasonic piezoelectric transducers can be found in ultrasonic cleaning machines. A piezo transducer operating at ultrasonic frequencies will oscillate very rapidly. When submerged in a fluid (normally water or a cleaning solvent), the ultrasonic transducer creates bubbles from the vibrations, exerting high amounts of force on molecules on the surface of the object being cleaned. The mechanical vibrations caused by ultrasonic piezo are powerful enough to remove debris and dirt. This cleaning process generally lasts for less than twenty minutes, demonstrating the power of ultrasonic transducers. 

This method for cleaning is extremely volatile and effective, and is widely used by jewelers, fishermen, dentists, and electricians in medical, commercial, and industrial applications. Due to the extra force provided by the ultrasonic transducer vibrations, potent chemicals or cleaning agents are either minimized or no longer required. In terms of effectiveness, safety, and size, ultrasonic transducers are the ideal tool for many applications. 

Benefits of Piezo Ultrasonic Transducers

Ultrasound transmitters and ultrasound transducers generate a lot of power and movement in a compact piezo element. For motor applications, piezoelectric ceramic products shine in their precision. Since the individual movements are so small, it is easy for the motors to be controlled to the micrometer level. By utilizing ultrasound transducers and ultrasound transmitters, these motors can be designed to be relatively efficient and simple, with few rotating parts and minimized maintenance over a wide range of operating conditions.

In ultrasonic cleaning applications, ultrasonic piezoelectric transducers are the most common vibratory apparatus in use today, with new products based on this technology being designed throughout many industries.

Piezo Direct offers a wide range of ultrasonic piezo products, including fully customizable piezo actuatorspiezoelectric sensorspiezo transducers, and ultrasonic nebulizers available in a variety of shapes. For more information about Piezo Direct’s fully custom capabilities and ultrasonic piezos, please contact Piezo Direct at 650-375-7003 or info@piezodirect.com to learn more about custom piezo elements.