Piezoelectricity is applied to a wide array of smart sensors and devices, and has become a driving force behind many sensors and devices used in the smart products industry — and as a basis for many gadgets we use on a daily basis, from ear buds to cell phones. So it’s useful to take a closer look at how the Piezoelectric Effect occurs and the technology behind it.

What is piezo?

Piezo is an electromechanical device that converts mechanical movements into electrical signals, which increase according to the strength of mechanical movements. The word piezoelectric is derived from the Greek ‘piezein’, which means to squeeze or press — ‘piezo’ is Greek for the word ‘push’.

The technology behind piezo

Piezo devices are created using non-conductive piezoelectric materials, crystals or ceramics. The most well-known piezoelectric material is quartz (SiO2), which is a naturally occurring  piezoelectric material. Piezoelectric materials can also be created artificially and are available in unlimited shapes and sizes. And when mechanical stress is applied to piezoelectric material it, generates a voltage that can be measured and processed, a phenomena called the Piezoelectric Effect.

One of the unique characteristics of the Piezoelectric Effect is that it is reversible, meaning that materials which exhibit the direct Piezoelectric Effect (the generation of electricity when stress is applied) also exhibit the converse Piezoelectric Effect. In this case the  voltage applied will change the shape of solid matter by a small amount (up to 4% change in volume).

Chart showing piezoelectric ceramic features . Image credit: nec-tokin

Piezoelectric applications for smart sensors

Many commonly used devices are based on the Piezoelectric Effect. Microphones and speakers are good examples, where  sound vibration is the mechanical stress that is  converted into, or converted from electrical signals, respectively.

Microphones: Some microphones (such as contact microphones for percussion instruments) use piezoelectric materials to convert sound vibrations into an electrical signal (the direct Piezoelectric Effect).

Speakers: Speakers operate by converting electrical signals in order to to vibrate the speaker membrane and create sound (using the reverse Piezoelectric Effect). Piezoelectric speakers are featured in virtually every application that needs to efficiently produce sound from a small electronic gadget. These types of speakers are usually inexpensive and require little power to produce relatively large sound volumes.

Piezoelectric speakers can often be found in devices such as the following:

  • Cell phones
  • Ear buds
  • Sound-producing toys
  • Musical greeting cards
  • Musical balloons

The Piezoelectric Effect is the technology that forms the basis of many electrical devices such as:

  • Motion detectors
  • Pressure sensors
  • Piezoelectric relays
  • Piezoelectric motors
  • Fast response solenoids
  • Ultrasonic sensors (as transducer)
  • Ultrasound imaging   

As the technology behind many smart sensors and devices that we use every day, it’s not surprising how the Piezoelectric Effect has come to influence our lives on a daily basis.

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Yarden Hod
Yarden has exceptional experience in all stages of the product development life cycle and has a strong interest in consumer behavior and cognitive skills development. In her free time, Yarden enjoys modern dance and mastering the latest addictive game!