What Is the Piezoelectric Effect?

How does it work?

The piezoelectric effect is displayed when a piece of a solid is under a stress (pinched or pulled). When certain solids are pinched or pulled, a voltage is produced. The reverse could also be displayed: applying a voltage could cause a material to expand or contract. In the diagram, we see a piece of quartz. In its natural state, it is electrically neutral. When it is pulled in the direction shown, the molecule stretches and develops an uneven electric charge distribution. This leads to the top of it becoming more positively charged and the bottom more negatively charged. When compressed in the direction shown, the molecule has a positive charge on the bottom and a negative charge on the top.

Do not get this confused with triboluminescence: piezoluminescence occurs with the addition of stress on a solid, while triboluminescence occurs with the fracture of a solid.

What are they used for?

They are used in these applications, to name a few:

  • Transducers
  • Microphones
  • Speakers and amplifiers
  • Ultrasound (imaging, non-invasive surgery)
  • Headphones
  • Inkjet printers
  • Fire alarms
  • Microwave ovens
  • Humidifiers
  • Guitar pickups
  • Ignition (spark plugs, lighters, grills, blowtorches, etc.)
  • Micro-Electro-Mechanical Systems (MEMS)
  • Self-steering bullets
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