Essay Example on the Applications of Piezoelectricity

Generally, mechanical energy can be converted into electrical energy through electromagnetism. However, there are other direct physical phenomenon that changes mechanical energy into electricity and one of them is piezoelectricity. "Piezoelectric effect is the capability of certain materials to generate an electric charge in response to applied mechanical stress and the reverse is true" (Cady, 2013). Pierre and Jacques Curie were the first people to prove piezoelectric effect in 1880. Piezo is obtained from 'Piezein' which is a Greek word with the meaning of squeezing or pressing. The existence of the piezoelectric effect is based on two domains; one of them is direct (Mechanical stress is converted to emf) and the other is Reverse (electrical energy is converted to mechanical compression). The paper, therefore, aims to exemplify the applications of piezoelectricity, its examples and some of the products that use piezoelectricity in generating electricity.

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Applications

Piezoelectric materials have intrinsic characteristics making it find its application in wide range of materials including sensors, crystal oscillator, actuators and ultrasonic application among many others. Sensors and actuators are significant in instrumentation and in automotive sectors. Almost all microprocessor-based systems use the crystal oscillator (Mason, 2015). Exclusion of production materials which are not significant, demand for piezoelectric before 2010 was very high. Today, there is faster growth rate hence finding applications in various fields.

Piezoelectric Motor

This is an electric motor type that is based on shape changes of the material of a piezoelectric especially when there is an application of electric field. These motors utilize the piezoelectric effect of converse by producing the acoustic material or ultrasonic vibrations so as to create a linear or rotary movement due to friction (Cady, 2013). Even though the basic mechanism is the same, distinct types of motors including high torque motor and stepper motor, have respective distinct design and operating principle. As shown below, the motors are small in sizes.

In high precision and linear movement, piezoelectric are used in camera lens movement, radar rotation, and control of a valve in very small scale. Though it is impossible to get large scale devices due to the necessity of a high-frequency supply of power, these motors have a high resolution and high accuracy and their design are scalable.

Sensors and Actuators

Materials of piezoelectric are useful in the direct conversion of pressure, temperature, acceleration, strain or force into emf of electricity. Therefore, by means of such materials, such parameters can be sensed or measured. The versatile tools of the sensors of piezoelectric are useful in the measurement of various processes including assurance of quality, process control and industrial growth research. It was in 1950 that piezoelectric effect became useful in piezo sensors such as pressure sensors, strain gauge, electric guitar etc. the mechanism through which environment is acted by a control system is known as an actuator. Energy is converted to motion when energy is derived from electric current, the pressure of the hydraulic fluid, or the pneumatic pressure. Here, the converse effect of the piezoelectric actuator is used. The material can adjust its shape when there is the application of voltage hence providing pressure in microscale at a very high precision compared to hydraulic and pneumatic pressure. The advanced technology of piezoelectric version of actuator gives an amplified actuator that finds use in operating small nozzles. Some of these include the x-ray shutter, movement of the camera lens, diesel engines which some don't require any lubricants. Although the only movement of microscale is possible and the actuator may need above 100 voltages, these actuators have a high accuracy compared to other sensors and most don't require a lubricant in the moving parts.

Power Source of High Voltage

When sufficient mechanical stress is applied, some substances of piezoelectric such as quartz are used in generating potential differences of thousand volts. The high voltage pulse is used in generating a spark, piezoelectric transformer, and harvesting of micro-scale energy (Wu & Narimani, 2017). Some example use is stove lighter of LPG and cigarette lighter, microscale of energy harvesting and piezoelectric transformer. Though voltage is produced in pulse form, this system of spark creation does not need any source power such as a battery. Also, a high voltage pulse can be produced with no any instrument of electricity.

Application Mechanism of Piezoelectricity

Piezoelectricity finds a wide range of application in various fields such as domestic, automobile biomedical etc. some of those machines of applications include:

LPG Stove Lighter Mechanism

In the past, one of the most progressing and form of prosperity to man was the use of stones in sparking and lighting a fire for cooking. Today, most of our kitchen uses the LPG stove and only a small force of thumb is required for lighting the stove (Wu & Narimani, 2017). There is even no use of matchbox as most are using the simple light. Even though the battery has some limitations of giving limited times of sparks, there are some electric lighters that are still using the battery power. As a result, all battery lighters have been replaced by piezoelectric lighters in today's era.

Outside of gas lighter, there is a hammer and a spring connected to the bottom and a piezoceramic crystal attached on the other end of lighter. The hammer moves away from the crystal whenever the bottom is pressed and the spring gets charged. However, the spring can get discharged when the bottom is hard-pressed beyond the edge and hence release the hammer (Shrout & Zhang, 2016). Later, a high voltage of 800v is produced crossways to the crystal whenever the hammer hits the piezo-ceramic. This high voltage leads to the breakdown of air and production of spark which thereafter lights up the gas that comes from outside the tank. PTZ (Lead Zirconate Titanate) makes the ceramic that is of low cost but high sensitivity.

Producer of piezoelectric spark is small devices used in LPG and cigarette lighters. A single switch in cigarette lighters glows the fire by producing a spark and releasing gas. Spark can occur once but fire exists until the switch is hard-pressed.

The figure below shows the distinct cigarette parts and a producer of piezoelectric spark. It is very safe to use, it is reliable with long duration and does not require any battery.

Quartz Clock Mechanism

In this world, time is the only measurement that has power over everything. Even though we have marked and assumed the years, months and days, there is no start and end point of timescale. For us to be accurate in tracking time, we need a clock on our side. In civilization days, the man kept track of time through the use of many concepts including the sun clock and hourglass. This then moved to mechanical clock and pendulum clock which at the end gave lots of challenges (Beaver, Liang, Sun, Wu & Xie, 2017). Today, there is the use of quartz clock (silicon dioxide, SiO2) which is a material of piezoelectric and such clocks include the digital clocks, wrist watch, wall clock etc.

Inside part of a clock, there is a Quartz Crystal Oscillator similar to a simple circuit component and is bifurcated like a tuning fork. Current is provided by the battery to input microchip circuit that makes the quartz crystal to oscillate to 32768 times per second. The output microchip circuit turns the crystal oscillation into regular electric pulses of one per second by detecting it (Beaver, Liang, Sun, Wu & Xie, 2017). Electrical energy is converted into mechanical power when pulses of electricity drive the stepping motor of miniature electric. The stepping motor of electric turns the gear which as a result keeps time by sweeping hands around the face of the clock. For a digital clock, the output of the second microchip is offered to display of seven segment and counters are used for calculation of minutes and hours. Since the constant vibration frequency of quartz crystal is 32,768Hz and due to changes in temperature it may vary to 0.06HZ, it gives the reason as to why clock gains or lose small time. The crystal oscillator is not the only application in the clock, but almost in every digital system that needs a frequency standard to run. Such system uses the distinct size of the crystal oscillator with distinct frequency rating as shown below.

Piezoelectric Transformer

The transformer is a device of the static piece that steps up or down to keeps same voltage value or current hence maintaining the frequency constant by electromagnetism principle. In a common transformer, there are two windings known as primary and secondary and they are isolated electrically but linked magnetically through the core. An alternative to wire wound magnetic transformers is the piezoelectric transformers (Forrester, Davidson, Foster, Horsley & Stone, 2018). They behave in a distinct way since they are lighter and smaller and also they have great electric isolation and no stray flux of magnetic. As a result, they have found use in cold cathode fluorescent lamp (CCFL) and back lightning for most laptops. The piezoelectric transformer is of different modes as shown below.

The first figure illustrates a longitudinal mode where the direction of operating stress, T, is parallel to the direction of polarization. The second figure is the transverse mode where the operating stress direction is perpendicular to the direction of polarization. Piezoelectric transformers exchange electric potential with mechanical force, contrary to a magnetic transformer that is based on the transfer of electromagnetic energy.

Conclusion

Piezoelectricity is a revolutionary concept that is finding application in many fields of industries, automobiles etc. since the material needed to make piezoelectricity is simple and easy to produce; most industries should take a step towards using it as a way of development and digitalizing of all devices.

References

Beaver, W. D., Liang, H., Sun, X., Wu, G., & Xie, J. (2017). U.S. Patent Application No. 15/403,168.

Cady, W. G. (2013). Piezoelectricity: an introduction to the theory and applications of electromechanical phenomena in crystals.

Forrester, J., Davidson, J., Foster, M., Horsley, E., & Stone, D. (2018, April). Automated design tools for piezoelectric transformer-based power supplies. In 9th International Conference on Power Electronics, Machines and Drives. IET.

Mason, W. P. (2015). Piezoelectricity, its history, and applications. The Journal of the Acoustical Society of America, 70(6), 1561-1566.

Shrout, T. R., & Zhang, S. J. (2016). Lead-free piezoelectric ceramics: Alternatives for PZT?. Journal of Electroceramics, 19(1), 113-126.

Wu, B., & Narimani, M. (2017). High-power converters and AC drives (Vol. 59). John Wiley & Sons.