Smart+Materials+and+applications+1

**Piezoelectric materials**

Piezoelectric materials are one of the most important smart materials used these days. It has a lot of applications due its unique piezoelectric effect.

Piezoelectricity describes the relation between mechanical stresses and electric charges in solids. The piezoelectric effect states that when a mechanical stress is applied on a piezoelectric material, an electric voltage will be produced. This effect can be reversed, meaning that if the material is subjected on an electric voltage, the shape of the solid will change up to 4% of the solid’s volume.

[|Piezoelectric Effect]

History

The piezoelectric effect was discovered in 1880 by the Jacques and Pierre Curie brothers. They discovered the appearance of electrical charges on some crystals such as tourmaline, topaz, quartz, Rochelle salt and cane sugar when a mechanical stress is applied on them and this voltage was proportional to the stress.

But the Curie brothers did not predict that these ceramic would also exhibit the converse piezoelectric effect  which is a change in the solid’s volume when a voltage is applied. This property was mathematically deduced from fundamental thermodynamic principles by Lippmann in 1881.

[|Quartz] [|Topaz] [|Tourmaline] = = **Applications**

The Automotive Industry: Air bag sensors, air flow sensors, fuel atomizer, knock sensors.

Medical Industry: Disposable patient monitors, ultrasonic imaging

Computer industry: Disc Drives, inkjet printers

Military Industry: Guidance systems, hydrophones.

Consumer Industry: Cigarette Lighters, musical instruments

[|Cigarette lighters]

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