Introduction to Ultrasonic Transducer: Working Principle, Types and Applications

25 February 2021

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One type of sound-related transducer is the ultrasonic transducer. The electrical signals are transmitted to the target by these transducers and after the signal reaches the object, it returns to the transducer. This transducer tests the distance of the object in this method, not the amplitude of the signal. For the calculation of a few parameters, these transducers use ultrasonic waves.

Catalog

Frequency is characterized as the number of signals or waves that may occur at a fixed time. Hertz units for the frequency are (Hz). Based upon the frequency values, these frequencies are broken into many ranges. There is Very Low Frequency (VLF), Low Frequency (LF), Medium Frequency (MF), High Frequency (HF), Very High Frequency (VHF), Ultra High Frequency (UHF), Super High Frequency (SHF), and Highly High Frequency (SHF) (EHF). Depending on the type of frequency, the frequency range can vary. The VLF frequency spectrum varies between 3 and 30 kHz. The LF frequency spectrum varies between 30 kHz and 300 kHz. The MF frequency spectrum varies between 300 and 3000 kHz.

One type of sound-related transducer is the ultrasonic transducer. The electrical signals are transmitted to the target by these transducers and after the signal reaches the object, it returns to the transducer. This transducer tests the distance of the object in this method, not the amplitude of the signal. For the calculation of a few parameters, these transducers use ultrasonic waves. In different regions, it has a wide variety of uses. The ultrasonic wave frequency spectrum is over 20 kHz. These are primarily used in applications that measure distance. The ultrasonic transducer is indicated in the following illustration.

The HF frequency spectrum varies between 3 MHz and 30 MHz. The UHF frequency spectrum varies between 300 MHz and 3000 MHz. The SHF frequency spectrum varies from 3 GHz up to 30 GHz. The EHF frequency spectrum varies between 30 GHz and 300 GHz. A description of the ultrasonic transducer and its function is discussed in this article.

I. Ultrasonic Transducer Working Principle

This vibrates throughout the particular frequency spectrum when an electrical signal is added to this transducer and produces a sound wave. These sound waves fly and these sound waves will reflect the transducer's echo knowledge if some barrier appears. And this echo transforms into an electric pulse at the end of the transducer. The time interval between transmitting the sound wave to the receiving echo signal is determined by the transducer here. At 40 kHz, the ultrasonic transducer gives an ultrasonic pulse that passes through the air. Such transducers are safer than infrared transducers because dust, black materials, etc. are not influenced by these ultrasonic transducers/transducers. In suppressing noise distortion, ultrasonic transducers exhibit excellence.

Ultrasonic transducers are primarily used to use ultrasonic waves to assess the size. The following formula will calculate the distance:

D = ½ * T * C

Here, the distance is indicated by D

The time gap between transmitting and receiving ultrasonic waves is shown by T

C is a sonic velocity indication.

II. 

Ultrasonic Transducer Features

1.  Performance

The core of the ultrasound probe is a piezoelectric chip in its plastic or metal jacket. There are many kinds of materials that make up the wafer. The size of the wafer, such as diameter and thickness, are also different, so the performance of each probe is different, we must know its performance before use. The main performance indicators of ultrasonic transducers include:

2.  Working Frequency

The working frequency is the resonance frequency of the piezoelectric wafer. When the frequency of the AC voltage applied to its two ends is equal to the resonance frequency of the chip, the output energy is the highest and the sensitivity is the highest.

3.  Operating Temperature

Because the Curie point of piezoelectric materials is generally relatively high, especially the ultrasonic probe used for diagnosis uses low power, the operating temperature is relatively low, and it can work for a long time without failure. The temperature of medical ultrasound probes is relatively high and requires separate refrigeration equipment.

4.  Sensitivity

Mainly depends on the manufacturing wafer itself. The electromechanical coupling coefficient is large and the sensitivity is high; on the contrary, the sensitivity is low.

5.  System Components

It is composed of sending transducer (or wave transmitter), receiving transducer (or wave receiver), control part, and power supply part. The transmitter transducer is composed of a transmitter and a ceramic vibrator transducer with a diameter of about 15mm. The function of the transducer is to convert the electric vibration energy of the ceramic vibrator into super energy and radiate into the air; while the receiving transducer is transduced by the ceramic vibrator The transducer is composed of an amplifier and an amplifier circuit. The transducer receives the wave to produce mechanical vibration and converts it into electrical energy, which is used as the output of the transducer receiver to detect the transmitted super. In actual use, the ceramic vibrator of the transmitter is also used. It can be used as the ceramic vibrator of the receiver transducer company. The control part mainly controls the pulse chain frequency, duty cycle, sparse modulation, and counting and detection distance sent by the transmitter. The ultrasonic transducer power supply (or signal source) can be DC12V ± 10% or 24V ± 10%.

6.  Operating Mode

Ultrasonic transducers use the acoustic medium to perform non-contact and wear-free detection of the detected object. Ultrasonic transducers can detect transparent or colored objects, metal or non-metal objects, solid, liquid, and powdery substances. Its detection performance is hardly affected by any environmental conditions, including smoke and dust environments and rainy days.

7.  Advantages & Disadvantages

There are benefits and a few pitfalls to every system. The perks of the ultrasonic transducer will be discussed here.

• In any form of material, these ultrasonic transducers can be tested. All sorts of textures they can detect.

• The temperature, water, dust, or any of the ultrasonic transducers are not affected.

• Ultrasonic transducers can operate in a good way in every form of environment.

• It may also measure elevated sensing distances.

The following are the drawbacks of these transducers:

• Ultrasonic transducers are susceptible to the change in temperature. The ultrasonic reaction will alter this temperature variance.

• During the reading of reflections from small objects, thin and soft objects, it can face issues.

III. 

Ultrasonic Transducer Types

Based on factors like piezoelectric crystal arrangement, footprint, and frequency, there are different types of ultrasonic transducers available. They are:

Linear ultrasonic transducers - The structure of piezoelectric crystals is linear in this type of transducers.

Normal Ultrasonic - Transducers-Convex transducers are also known as this form. The piezoelectric crystal of this type is in a curvy shape. These are superior to in-depth tests.

Phased Array Ultrasonic Transducers - There is a limited footprint and low frequency of phased array transducers. (2 MHz-7 MHz)

The ultrasonic transducers again have distinct forms for non-destructive studies. Contact transducers, transducers of angle beams, transducers of delay lines, transducers of immersion, and transducers of dual components.

IV. 

Ultrasonic Transducer Applications

The Ultrasonic Transducers implementations are

In diverse fields, such as automotive, medical, etc, these transducers have many applications. Owing to ultrasonic waves, they have more uses. This helps to locate the targets, to determine the distance of the objects to the target, to find the object's location, to quantify the level, and to support the ultrasonic transducers.

In the medical area, the ultrasonic transducer is used for diagnostic tests, surgical instruments for cancer care, internal organ testing, heart checkups, ultrasonic transducers for eyes and uterus checkups.

Ultrasonic transducers have few major uses in the industrial sector. Via these transducers, in manufacturing line management, liquid level monitoring, wire break detection, people detection for counting, car detection, and many more, they can determine the distance of such objects to prevent a collision.