Focus on everyday piezo

After a slow start piezoelectricity today is used in everyday technology, from ultrasound scanners to electric guitars.

After spending the first few decades after its discovery as a lab curiosity, the piezoelectric effect (and reverse piezoelectric effect) has become a common part of many of the gadgets we routinely use.

Introduction

Piezoelectrics are useful for electronic components as they provide an accurate frequency due to several serendipitous properties. Quartz (silicon dioxide), the first commercially exploited piezoelectric material, is unaffected by most solvents and remains crystalline at very high temperatures.

One of piezo’s best known applications is as an ignition source, such as those used in gas hobs and cigarette lighters. Pushing a button releases a spring loaded hammer onto a piezo ceramic. This generates a small electric current, which flows across a spark gap and ignites the gas.



Printing

The reverse piezoelectric effect is utilised in printing equipment, both in the home and on industrial production lines.

Most inkjet printers use piezoelectric material in an ink-filled chamber behind each nozzle. When a charge is applied the material flexes, forcing a drop of ink onto the paper.

Acoustic uses

The reverse piezoelectric effect is also used in simple speakers, for example in watch beepers, portable stereo systems, and in mobile phones and computers.

When a voltage is applied across the surface of a piezoelectric crystal, it responds by flexing. A surrounding mechanical diaphragm converts the electrical energy into acoustic energy. These speakers are cheap and resistant to overload, so are common in applications where low price and reliability are important.

Piezoelectric components can detect sound as well as producing it. Piezoelectric pickups on guitars detect small changes in pressure as the strings vibrate. This produces alternating current, which is fed to an amplifier.

Ultrasound uses

The best known use of the piezoelectric effect is in ultrasonic transducers, used for medical ultrasound imaging.

When an alternating electric current is applied to piezo crystals, they change shape rapidly. The rapid shape changes produce high frequency sound waves.

Ultrasound has a wide range of medical and industrial applications, but also many commercial applications. Examples include TV remote controls and echolocation devices used to help drivers park their car.

Future applications

New applications and potential uses of piezoelectric components are being identified in a number of different fields.

Piezoelectric components’ durability and low cost mean that as research and development continues, the range of commercial applications will also continue to grow rapidly.

The market for piezoelectric components is expected to see double digit growth in the next five years. New devices such as piezoelectric generators will see the highest growth, estimated at 51.5% annually.

Piezoceramic filters are used in:
Radios and televisions
Watch bleepers
Battery operated smoke detector alarms

Ultrasonic transducers are integral to:
Sonar
Biomedical imaging and therapy
TV remote controls
Echo-location (ie the distance determining bleep that helps motorists park)