Applications of piezo-electricity

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1. APPLICATIONS OF PIEZOELECTRICITY By- Sakti Prasanna Muduli 1

2. OVERVIEW Introduction Cause of piezoelectricity Discovery Materials exhibiting this property Field of applications Mechanism of some applications Conclusion 2

3. What the piezoelectricity is Piezoelectric Effect is the ability of certain materials to generate an electric charge in response to applied mechanical stress . 3

4. Reverse piezoelectric effect: when voltage is applied on two opposite surfaces of a piezoelectric material that shows expansion or contraction. Piezoelectricity is derived from the Greek word “ piezo ” or “ piezein ” which means to squeeze or press. 4

5. CAUSE OF PIEZOELECTRICITY Piezoelectric effect is formed in crystal having no centre of symmetry. 5

6. DISCOVERY Piezoelectric effect was first proven in 1880 by the French Physicist brothers Pierre and Jacques Curie Pierre Curie Jacques Curie 6

7. MATERIALS EXHIBITING THE PROPERTY: NATURAL OCCURING MATERIALS: Quartz(SiO 2 ) Sucrose (table sugar) Rochelle salt Topaz(Al 2 SiO 4 (F,OH) 2 ) Dry bone Dentine SYNTHETIC MATERIALS: Barium titanate (BaTiO 3 ) Lead zirconate titanate Potassium niobate (KNbO 3 ) Bismuth ferrite (BiFeO 3 ) Sodium niobate (NaNbO 3 ) 7

8. APPLICATION FIELDS A. As high voltage power source: LPG stove Lighter and Cigarette lighter Energy harvesting in micro scale (New concept) Piezoelectric transformer (New concept) B. Sensors and Actuators: High precision piezoelectric microphones Electric guitar pickup Piezoelectric micro balance (very sensitive chemical and biological sensors) Strain gauge Electronic drum pad Pressure sensors Accelerometer (New concept) Loud speaker and buzzer(Actuator) 8

9. C. As frequency standard: General quartz clock Crystal oscillator D. Sonic and Ultra sonic applications Underwater submarine detection Ultrasound in medical technology Metal fault detection 9

10. E. Piezoelectric motor: A piezoelectric motor or piezo motor is a type of electric motor based upon the change in shape of a piezoelectric material when an electric field is applied. Piezoelectric motors make use of the converse piezoelectric effect whereby the material produces acoustic or ultrasonic vibrations in order to produce a linear or rotary motion due to friction. 10

11. Mechanism of piezo -motor: 11

12. Uses of piezoelectric motor: Movement of camera lens Rotation of radar Very small scale valve control Laser movement in case of biomedical modern operations Advantages : No stray field effect High resolution and high accuracy Rapid response Wide range of angular steps and angular velocities Disadvantages: Necessity for a high frequency power supply Large scale devices are impossible 12

13. Mechanism of Lpg stove lighter When a piezoelectric material is hammered a high voltage is generated and causes spark. Which is the basis of piezoelectric LPG lighter. 13

14. Piezoelectric Igniter 14 Lead zirconate titanate (PZT)

15. Cigarette Lighters: 15

16. Mechanism of Quartz clock 16

17. Clock uses piezoelectric quartz crystal Oscillator as frequency standard for tracking the time. Battery provides current to input microchip circuit Input microchip circuit makes quartz crystal (precisely cut and shaped like a tuning fork) oscillate (vibrate) 32768 times per second . Output microchip circuit detects the crystal's oscillations and turns them into regular electric pulses, one per second . Electric pulses drive miniature electric stepping motor . This converts electrical energy into mechanical power. Electric stepping motor turns gears. Gears sweep hands around the clock-face to keep time 17

18. Crystal Oscillators: 18 Crystal oscillators are not only used in clock but in all microprocessor based digital systems

19. Piezoelectric transformer 19

20. An ac voltage is applied to the V IN electrodes, causing mechanical expansion and compression in the thickness direction . This displacement on the primary is transferred as a force in the longitudinal or length direction . Mechanical resonance occurs Due to transverse and longitudinal vibration. Voltage gain is a function of the PZT is given by 20 Where g(w) is piezoelectric material co-efficient

21. Mechanism of Piezoelectric accelerometer 21

22. Energy harvesting using piezoelectricity Vibrations can be used to generate electricity in micro scale using piezoelectric materials. Sources of vibration : Walk sides Railway tracks Shoes or boots Mobile keypad and keyboard Floor mat, tiles and carpets 22

23. 23 This is the circuit for utilisation of generated energy. The generated ac voltage is rectified and stored in a capacitor for use. Also trickle charge can be provided to a battery to recharge it.

24. Conclusion Revolutionary concept in the field of sensors and transducers. There are also some future aspects those need to be developed such as piezoelectric accelerometer, motor, underwater acoustic transducers, piezoelectric transformers ect . Energy harvesting through piezoelectricity is both economical and eco-friendly . 24

25. references BOOKS J.P. Bentley, Principles of Measurement Systems- Pearson Education William D. Callister , David G. Rethwisch , Material Science and Engineering an introduction, Wiley Publication How it works, The clock, A CBT Publication K. Krishna Murty , How things work ?, Pustak Mahal WEB https://en.wikipedia.org/wiki/Piezoelectricity http://www.explainthatstuff.com/quartzclockwatch.html http://www.mmech.com/transformers https://en.wikipedia.org/wiki/Piezoelectric_accelerometer http://www.explainthatstuff.com/accelerometers.html https:// en.wikipedia.org/wiki/Piezoelectric_motor 25

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