The piezoelectric sensor is used to sense bending, touch, vibration, and shock. Its fundamental principle is that whenever a structure moves, it experiences acceleration. A piezoelectric shock sensor can generate a charge when physically accelerated. This combination of qualities is then applied to customize response or reduce noise and vibration.
Why is this important? Vibration and stress can reduce the life of any electrical or electromechanical system. Sensitive leads and bond wires can be stressed, particularly when exposed to continuous vibration. Solder connections might break away, and PCB traces can slightly cut from impact and impulse shock, resulting in the most difficult sort of system failure to debug: an intermittent failure.
What is Piezoelectric Sensor?
A sensor that operates on the basis of piezoelectricity is referred to as a piezoelectric sensor. Piezoelectricity is a phenomenon that produces electricity when force is applied on a material. A piezoelectric sensor is a device that uses the piezoelectric effect to convert changes in acceleration, strain, pressure, and force into electrical charge. The piezoelectricity generated is proportional to the stress applied to the substrates of the strong piezoelectric crystal.
How it works?
Pierre and Jacques Curie discovered the piezoelectric phenomenon in the late 19th century. They found that crystals like tourmaline and quartz could convert mechanical energy into electric energy. The voltage caused by pressure is proportional to the applied pressure, thus piezoelectric devices can detect single-pressure events as well as repeating events.
despite everything, the capacity of certain crystals to exhibit electrical charges under mechanical loading was of no practical use until very-high-input impedance amplifiers enabling engineers to magnify the signals produced by these crystals.
Piezoelectric sensors can be made from many materials, including tourmaline, gallium phosphate, salts, and quartz. Quartz is used in the majority of electronic applications because its growing technique has advanced significantly due to the invention of the reverse application of the piezoelectric effect, the quartz oscillator.
Sensors using the piezoelectric effect can operate on transverse, longitudinal, or shear stresses and are insensitive to electric fields and electromagnetic radiation. The response is also fairly linear across a large temperature range, making it an excellent sensor for challenging environments. For example, Gallium phosphate and tourmaline sensors can work at temperatures up to 1,000°C.
The physical architecture of the piezoelectric sensor is dependent on the type of sensor you want to develop.
Piezoelectric Effect
Piezo is a Greek word that means "press" or "squeeze". Piezoelectricity (also known as the piezoelectric effect) is the presence of an electrical potential across the sides of a crystal when subjected to mechanical stress through squeezing. In the working system, the crystal functions as a little battery, with a positive charge on one face and a negative charge on the other. To complete the circuit, two faces are joined together by wire, and current flows through it.
Mechanical stress analyzer: During building construction, stress analyzers are used for columns to monitor the voltage produced by stress and determine the resulting stress.
Gas lighters and cigarette lighters both use the piezoelectric effect. They produce an electric pulse as a result of the force generated by the trigger's quick interaction with the material inside.
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| Photo Credit-electricaltechnology.org |
Inverse Piezoelectric Effect
When an electric field is applied to crystal terminals, crystals experience mechanical stress, resulting in shape change. This is known as the inverse piezoelectric effect.
In our daily lives, wristwatches employ a quartz resonator to function as an oscillator. The element utilized is silicon dioxide. When an electric signal is supplied to the crystal, it vibrates, which aids in the periodic regulation of the watch's gears.
Buzzers are utilized in a variety of applications, including motor vehicles reverse signaling and computers. A specified amount of voltage with magnitude and frequency is supplied to the crystal, causing it to vibrate. The vibration is transformed to sound.
Working of Piezoelectric Sensor
When pressure or acceleration is applied to the PZT material, equal amounts of electrical charge are created across the crystal faces. The electrical charge will be proportionate to the applied pressure. The piezoelectric sensor cannot be used to measure static pressure. At constant pressure, the output signal will be zero. The operation of a piezoelectric sensor can be stated as:
- Charges in a piezoelectric crystal are exactly balanced in both symmetric and asymmetric arrangements.
- The effect of the charges cancels out, therefore there will be no net charge on the crystal faces.
- When a crystal gets squeezed, its charge becomes imbalanced. As a result, the effect of the charge is not canceled out, causing net positive and negative charges to appear on the opposing faces of the crystal.
- As a result, squeezing the crystal generates a voltage across the opposing face, which is known as piezoelectricity.
Application of Piezoelectric Sensor (use of piezoelectric sensor)
1. Piezoresistive Pressure Sensor
They are used to assess dynamic pressure. Turbulence, engine combustion, and other factors all contribute to dynamic pressure readings. Piezoresistive pressure sensors can be used to measure pressure changes in liquids and gases during cylinder pressure measurements or hydraulic processes. When a force is applied to the piezoelectric diaphragm, it produces an electric charge across the crystal faces. The output is measured as a voltage that is proportionate to the applied pressure.
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| Piezoelectric Pressure Sensor |
2. Ultrasound Transducer using Piezoelectric Crystals
In the ultrasound imaging system, ultrasound sensors produce ultrasonic waves. This involves attaching piezoelectric crystals to the front of the transducer, which aids in the generation of ultrasound waves. Since the transducer is held in one hand, its position is kept changing so that the ultrasonic wave flows through the body components to be examined and viewed. Sound waves travel through body tissue. The waves are reflected back to generate the image of the tissue.
Electrodes serve as a connection point between crystals and machines. When an electric signal is delivered to a crystal, the vibration produces an ultrasonic wave with frequencies ranging from 1.5 to 8 MHz.
3. Industrial applications
In industrial applications, piezoelectric sensors are employed in engine knock sensors, pressure sensors, and sonar equipment.
4. Actuator
Piezoelectric actuators are used for diesel fuel injectors, optical adjustments, ultrasonic cleaning, and welding.
5. Electrical appliance
Sensors are employed in a variety of electrical equipment, including dot matrix printers, inkjet printers, Piezo speakers, buzzers, and humidifiers.
6. Musical instrument
This sensor can also be found in musical instruments like Instrument pickups and microphone
