Editing Piezoelectricity (section)

===Actuators===

[[File:2007-07-24 Piezoelectric buzzer.jpg|thumb|Metal disk with piezoelectric disk attached, used in a [[buzzer]]]]

As very high electric fields correspond to only tiny changes in the width of the crystal, this width can be changed with better-than-[[micrometre|μm]] precision, making piezo crystals the most important tool for positioning objects with extreme accuracy—thus their use in [[actuators]].<ref name=shabestari>{{cite journal
|last1=Shabestari |first1=N. P.
|title=Fabrication of a simple and easy-to-make piezoelectric actuator and its use as phase shifter in digital speckle pattern interferometry
|journal=Journal of Optics
|date=2019 |volume=48 |issue=2 |pages=272–282
|doi=10.1007/s12596-019-00522-4|bibcode=2019JOpt...48..272P
}}</ref>
Multilayer ceramics, using layers thinner than {{nowrap|100 μm}}, allow reaching high electric fields with voltage lower than {{nowrap|150 V}}. These ceramics are used within two kinds of actuators: direct piezo actuators and [[amplified piezoelectric actuator]]s. While direct actuator's stroke is generally lower than {{nowrap|100 μm}}, amplified piezo actuators can reach millimeter strokes.
* [[Piezoelectric loudspeaker|Loudspeakers]]: Voltage is converted to mechanical movement of a metallic diaphragm.
* [[Ultrasonic cleaning]] usually uses piezoelectric elements to produce intense sound waves in liquid.
* [[Piezoelectric motor]]s: Piezoelectric elements apply a directional force to an [[axle]], causing it to rotate. Due to the extremely small distances involved, the piezo motor is viewed as a high-precision replacement for the [[stepper motor]].
* Piezoelectric elements can be used in [[laser]] mirror alignment, where their ability to move a large mass (the mirror mount) over microscopic distances is exploited to electronically align some laser mirrors. By precisely controlling the distance between mirrors, the laser electronics can accurately maintain optical conditions inside the laser cavity to optimize the beam output.
* A related application is the [[acousto-optic modulator]], a device that scatters light off soundwaves in a crystal, generated by piezoelectric elements. This is useful for fine-tuning a laser's frequency.
* [[Atomic force microscope]]s and [[scanning tunneling microscope]]s employ converse piezoelectricity to keep the sensing needle close to the specimen.<ref>{{cite book|chapter=The scanning mechanism for ROSETTA/MIDAS from an engineering model to the flight model |last1=Le Letty |first1=R. |last2=Barillot |first2=F. |last3=Lhermet |first3=N. |last4=Claeyssen |first4=F. |last5=Yorck |first5=M. |last6=Gavira Izquierdo |first6=J. |last7=Arends |first7=H. |bibcode=2001ESASP.480...75L |pages=75–81 |isbn=978-92-9092-761-7 |year=2001 |title=Proceedings of the 9th European Space Mechanisms and Tribology Symposium, 19–21 September 2001, Liège, Belgium |editor-first=R. A. |editor-last=Harris |series=ESA SP-480 |volume=480}}</ref>
* [[Inkjet printer]]s: On many inkjet printers, piezoelectric crystals are used to drive the ejection of ink from the inkjet print head towards the paper.
* [[Diesel engine]]s: High-performance [[common rail]] diesel engines use piezoelectric [[fuel injector]]s, first developed by [[Robert Bosch GmbH]], instead of the more common [[solenoid valve]] devices.
* Active vibration control using amplified actuators.
* [[X-ray]] shutters.
* XY stages for micro scanning used in infrared cameras.
* Moving the patient precisely inside active [[X-ray computed tomography|CT]] and [[Magnetic resonance imaging|MRI]] scanners where the strong radiation or magnetism precludes electric motors.<ref name="piezact">{{cite web |last=Simonsen |first=Torben R. |url=http://elektronikbranchen.dk/nyhed/dansk-elektronikvirksomhed-goer-klar-til-rumeventyr-efter-koeb-af-piezoteknologi |title=Piezo in space |website=Electronics Business |language=da |date=27 September 2010 |access-date=28 September 2010 |url-status=dead |archive-url=https://web.archive.org/web/20100929113331/http://elektronikbranchen.dk/nyhed/dansk-elektronikvirksomhed-goer-klar-til-rumeventyr-efter-koeb-af-piezoteknologi |archive-date=29 September 2010 }}</ref>
* [[Crystal earpiece]]s are sometimes used in old or low power radios.
* [[High-intensity focused ultrasound]] for localized heating or creating a localized [[cavitation]] can be achieved, for example, in patient's body or in an industrial chemical process.
* [[Refreshable braille display]]. A small crystal is expanded by applying a current that moves a lever to raise individual braille cells.
* Piezoelectric actuator. A single crystal or a number of crystals are expanded by applying a voltage for moving and controlling a mechanism or system.<ref name=shabestari/>
* Piezoelectric actuators are used for fine servo positioning in hard disc drives.<ref>{{cite web|url=https://documents.westerndigital.com/content/dam/doc-library/en_us/assets/public/western-digital/collateral/tech-brief/tech-brief-western-digital-micro-actuator.pdf|title=Second-generation Micro Actuator for Better Head-positioning Accuracy|website=Documents.westerndigital.com|access-date=March 10, 2022}}</ref><ref>{{cite web |url=https://www.seagate.com/files/staticfiles/docs/pdf/whitepaper/seagate-acutrac-TP624.1-1110US.pdf|title=Exceeding Capacity, Speed and Performance Expectations|website=Seagate.com|access-date=March 10, 2022}}</ref>