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Actuators

Metal disk with piezoelectric disk attached, used in abuzzer

As very high electric fields correspond to only tiny changes in the width of the crystal, thiswidth can be changed with better-than-mprecision, making piezo crystals the most important

tool for positioning objects with extreme accuracy thus their use in actuators. Multilayer

ceramics, using layers thinner than 100 m, allow reaching high electric fields with voltage

lower than 150 V. These ceramics are used within two kinds of actuators: direct piezo actuators

andAmplified piezoelectric actuators.While direct actuator's stroke is generally lower than 100

m, amplified Piezo actuators can reach millimeter strokes.

Loudspeakers:Voltage is converted to mechanical movement of a piezoelectric polymerfilm.

Piezoelectric motors:Piezoelectric elements apply a directional force to anaxle,causingit to rotate. Due to the extremely small distances involved, the piezo motor is viewed as a

high-precision replacement for thestepper motor.

Piezoelectric elements can be used inlaser mirror alignment, where their ability to movea large mass (the mirror mount) over microscopic distances is exploited to electronically

align some laser mirrors. By precisely controlling the distance between mirrors, the laserelectronics can accurately maintain optical conditions inside the laser cavity to optimize

the beam output.

A related application is theacousto-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.
http://en.wikipedia.org/wiki/Buzzerhttp://en.wikipedia.org/wiki/Micrometrehttp://en.wikipedia.org/wiki/Actuatorshttp://en.wikipedia.org/wiki/Amplified_piezoelectric_actuatorhttp://en.wikipedia.org/wiki/Loudspeakershttp://en.wikipedia.org/wiki/Piezoelectric_motorhttp://en.wikipedia.org/wiki/Axlehttp://en.wikipedia.org/wiki/Stepper_motorhttp://en.wikipedia.org/wiki/Laserhttp://en.wikipedia.org/wiki/Acousto-optic_modulatorhttp://en.wikipedia.org/wiki/File:2007-07-24_Piezoelectric_buzzer.jpghttp://en.wikipedia.org/wiki/Acousto-optic_modulatorhttp://en.wikipedia.org/wiki/Laserhttp://en.wikipedia.org/wiki/Stepper_motorhttp://en.wikipedia.org/wiki/Axlehttp://en.wikipedia.org/wiki/Piezoelectric_motorhttp://en.wikipedia.org/wiki/Loudspeakershttp://en.wikipedia.org/wiki/Amplified_piezoelectric_actuatorhttp://en.wikipedia.org/wiki/Actuatorshttp://en.wikipedia.org/wiki/Micrometrehttp://en.wikipedia.org/wiki/Buzzer


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Atomic force microscopes and scanning tunneling microscopes employ conversepiezoelectricity to keep the sensing needle close to the specimen.

[33]

Inkjet printers: On many inkjet printers, piezoelectric crystals are used to drive theejection of ink from the inkjet print head towards the paper.

Diesel engines: High-performance common rail diesel engines use piezoelectric fuelinjectors,first developed byRobert Bosch GmbH,instead of the more commonsolenoid

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 CT and MRI scanners where the strong

radiation or magnetism precludes electric motors.[34]

Crystal earpieces are sometimes used in old or low power radios. High-intensity focused ultrasound for localized heating or creating a localizedCavitation

can be achieved, for example, in patient's body or in an industrial chemical process

Frequency standard

The piezoelectric properties of quartz are useful asstandard of frequency.

Quartz clocks employ a crystal oscillator made from a quartz crystal that uses acombination of both direct and converse piezoelectricity to generate a regularly timed

series of electrical pulses that is used to mark time. The quartz crystal (like any elastic

material) has a precisely defined natural frequency (caused by its shape and size) at

which it prefers to oscillate, and this is used to stabilize the frequency of a periodic

voltage applied to the crystal.

The same principle is critical in all radio transmitters and receivers, and in computerswhere it creates aclock pulse.Both of these usually use afrequency multiplier to reach

gigahertz ranges.
http://en.wikipedia.org/wiki/Atomic_force_microscopehttp://en.wikipedia.org/wiki/Scanning_tunneling_microscopehttp://en.wikipedia.org/wiki/Piezoelectricity#cite_note-33http://en.wikipedia.org/wiki/Piezoelectricity#cite_note-33http://en.wikipedia.org/wiki/Piezoelectricity#cite_note-33http://en.wikipedia.org/wiki/Inkjet_printerhttp://en.wikipedia.org/wiki/Diesel_enginehttp://en.wikipedia.org/wiki/Common_railhttp://en.wikipedia.org/wiki/Fuel_injectorhttp://en.wikipedia.org/wiki/Fuel_injectorhttp://en.wikipedia.org/wiki/Robert_Bosch_GmbHhttp://en.wikipedia.org/wiki/Solenoid_valvehttp://en.wikipedia.org/wiki/Solenoid_valvehttp://en.wikipedia.org/wiki/X-rayhttp://en.wikipedia.org/wiki/X-ray_computed_tomographyhttp://en.wikipedia.org/wiki/Magnetic_resonance_imaginghttp://en.wikipedia.org/wiki/Piezoelectricity#cite_note-piezact-34http://en.wikipedia.org/wiki/Piezoelectricity#cite_note-piezact-34http://en.wikipedia.org/wiki/Piezoelectricity#cite_note-piezact-34http://en.wikipedia.org/wiki/Crystal_earpiecehttp://en.wikipedia.org/wiki/High-intensity_focused_ultrasoundhttp://en.wikipedia.org/wiki/Cavitationhttp://en.wikipedia.org/wiki/Frequency_standardhttp://en.wikipedia.org/wiki/Quartz_clockhttp://en.wikipedia.org/wiki/Crystal_oscillatorhttp://en.wikipedia.org/wiki/Elasticity_%28physics%29http://en.wikipedia.org/wiki/Oscillatorhttp://en.wikipedia.org/wiki/Radiohttp://en.wikipedia.org/wiki/Transmitterhttp://en.wikipedia.org/wiki/Receiver_%28radio%29http://en.wikipedia.org/wiki/Computerhttp://en.wikipedia.org/wiki/Clock_pulsehttp://en.wikipedia.org/wiki/Frequency_multiplierhttp://en.wikipedia.org/wiki/Frequency_multiplierhttp://en.wikipedia.org/wiki/Clock_pulsehttp://en.wikipedia.org/wiki/Computerhttp://en.wikipedia.org/wiki/Receiver_%28radio%29http://en.wikipedia.org/wiki/Transmitterhttp://en.wikipedia.org/wiki/Radiohttp://en.wikipedia.org/wiki/Oscillatorhttp://en.wikipedia.org/wiki/Elasticity_%28physics%29http://en.wikipedia.org/wiki/Crystal_oscillatorhttp://en.wikipedia.org/wiki/Quartz_clockhttp://en.wikipedia.org/wiki/Frequency_standardhttp://en.wikipedia.org/wiki/Cavitationhttp://en.wikipedia.org/wiki/High-intensity_focused_ultrasoundhttp://en.wikipedia.org/wiki/Crystal_earpiecehttp://en.wikipedia.org/wiki/Piezoelectricity#cite_note-piezact-34http://en.wikipedia.org/wiki/Magnetic_resonance_imaginghttp://en.wikipedia.org/wiki/X-ray_computed_tomographyhttp://en.wikipedia.org/wiki/X-rayhttp://en.wikipedia.org/wiki/Solenoid_valvehttp://en.wikipedia.org/wiki/Solenoid_valvehttp://en.wikipedia.org/wiki/Robert_Bosch_GmbHhttp://en.wikipedia.org/wiki/Fuel_injectorhttp://en.wikipedia.org/wiki/Fuel_injectorhttp://en.wikipedia.org/wiki/Common_railhttp://en.wikipedia.org/wiki/Diesel_enginehttp://en.wikipedia.org/wiki/Inkjet_printerhttp://en.wikipedia.org/wiki/Piezoelectricity#cite_note-33http://en.wikipedia.org/wiki/Scanning_tunneling_microscopehttp://en.wikipedia.org/wiki/Atomic_force_microscope


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Piezoelectric motors

A slip-stick actuator.

Main article:Piezoelectric motor

Types of piezoelectric motor include:

Thetraveling-wave motor used forauto-focus inreflex cameras Inchworm motors for linear motion

Rectangular four-quadrant motors with high power density (2.5 W/cm

3

) and speedranging from 10 nm/s to 800 mm/s.

Stepping Piezo motor, usingstick-slip effect.

All these motors, except the stepping stick-slip motor work on the same principle. Driven by

dual orthogonal vibration modes with aphase difference of 90, the contact point between two

surfaces vibrates in anellipticalpath, producing africtional force between the surfaces. Usually,

one surface is fixed causing the other to move. In most piezoelectric motors the piezoelectric

crystal is excited by a sine wave signal at the resonant frequency of the motor. Using the

resonance effect, a much lower voltage can be used to produce high vibration amplitude.

Stick-slip motor works using the inertia of a mass and the friction of a clamp. Such motors

can be very small. Some are used for camera sensor displacement, thus allowing an anti-shake

function.
http://en.wikipedia.org/wiki/Piezoelectric_motorhttp://en.wikipedia.org/w/index.php?title=Traveling-wave_motor&action=edit&redlink=1http://en.wikipedia.org/wiki/Auto-focushttp://en.wikipedia.org/wiki/Single_lens_reflexhttp://en.wikipedia.org/wiki/Inchworm_motorhttp://en.wikipedia.org/wiki/Watthttp://en.wikipedia.org/wiki/Stick-sliphttp://en.wikipedia.org/wiki/Phase_%28waves%29http://en.wikipedia.org/wiki/Ellipsehttp://en.wikipedia.org/wiki/Frictionhttp://en.wikipedia.org/wiki/Sine_wavehttp://en.wikipedia.org/wiki/File:Slip-stick_actuator_operation.svghttp://en.wikipedia.org/wiki/Sine_wavehttp://en.wikipedia.org/wiki/Frictionhttp://en.wikipedia.org/wiki/Ellipsehttp://en.wikipedia.org/wiki/Phase_%28waves%29http://en.wikipedia.org/wiki/Stick-sliphttp://en.wikipedia.org/wiki/Watthttp://en.wikipedia.org/wiki/Inchworm_motorhttp://en.wikipedia.org/wiki/Single_lens_reflexhttp://en.wikipedia.org/wiki/Auto-focushttp://en.wikipedia.org/w/index.php?title=Traveling-wave_motor&action=edit&redlink=1http://en.wikipedia.org/wiki/Piezoelectric_motor


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Reduction of vibrations and noise

Different teams of researchers have been investigating ways to reduce vibrations in

materials by attaching Piezo elements to the material. When the material is bent by a vibration in

one direction, the vibration-reduction system responds to the bend and sends electric power to

the Piezo element to bend in the other direction. Future applications of this technology are

expected in cars and houses to reduce noise.

In a demonstration at the Material Vision Fair in Frankfurt in November 2005, a team

from TU Darmstadt inGermany showed several panels that were hit with a rubber mallet, and

the panel with the Piezo element immediately stopped swinging.

Piezoelectric ceramic fiber technology is being used as an electronic damping system on

someHEADtennis rackets.[35]

Infertility treatment

In people with previous total fertilization failure, piezoelectric activation of oocytes

together with intra cytoplasmic sperm injection (ICSI) seems to improve fertilization

outcomes.[36]

Surgery

A recent application of piezoelectric ultrasound sources is piezoelectric surgery, also

known as piezosurgery.[3]

Piezosurgery is a minimally invasive technique that aims to cut a

target tissue with little damage to neighboring tissues. For example, Hoigne et al .[37]

Reported its

use in hand surgery for the cutting of bone, using frequencies in the range 2529 kHz, causing

micro vibrations of 60210 m. It has the ability to cut mineralized tissue without cutting

neurovascular tissue and other soft tissue, thereby maintaining a blood-free operating area, better

visibility and greater precision.[38]
http://en.wikipedia.org/wiki/Frankfurthttp://en.wikipedia.org/wiki/Darmstadt_University_of_Technologyhttp://en.wikipedia.org/wiki/Germanyhttp://en.wikipedia.org/wiki/Head_%28company%29http://en.wikipedia.org/wiki/Tennis_rackethttp://en.wikipedia.org/wiki/Piezoelectricity#cite_note-35http://en.wikipedia.org/wiki/Piezoelectricity#cite_note-35http://en.wikipedia.org/wiki/Piezoelectricity#cite_note-35http://en.wikipedia.org/wiki/Total_fertilization_failurehttp://en.wikipedia.org/wiki/Intracytoplasmic_sperm_injectionhttp://en.wikipedia.org/wiki/Piezoelectricity#cite_note-36http://en.wikipedia.org/wiki/Piezoelectricity#cite_note-36http://en.wikipedia.org/wiki/Piezoelectricity#cite_note-36http://en.wikipedia.org/wiki/Piezosurgeryhttp://en.wikipedia.org/wiki/Piezoelectricity#cite_note-Manbachi.2C_A._and_Cobbold_R.S.C._2011_187.E2.80.93196-3http://en.wikipedia.org/wiki/Piezoelectricity#cite_note-Manbachi.2C_A._and_Cobbold_R.S.C._2011_187.E2.80.93196-3http://en.wikipedia.org/wiki/Piezoelectricity#cite_note-Manbachi.2C_A._and_Cobbold_R.S.C._2011_187.E2.80.93196-3http://en.wikipedia.org/wiki/Piezoelectricity#cite_note-37http://en.wikipedia.org/wiki/Piezoelectricity#cite_note-37http://en.wikipedia.org/wiki/Piezoelectricity#cite_note-37http://en.wikipedia.org/wiki/Piezoelectricity#cite_note-38http://en.wikipedia.org/wiki/Piezoelectricity#cite_note-38http://en.wikipedia.org/wiki/Piezoelectricity#cite_note-38http://en.wikipedia.org/wiki/Piezoelectricity#cite_note-38http://en.wikipedia.org/wiki/Piezoelectricity#cite_note-37http://en.wikipedia.org/wiki/Piezoelectricity#cite_note-Manbachi.2C_A._and_Cobbold_R.S.C._2011_187.E2.80.93196-3http://en.wikipedia.org/wiki/Piezosurgeryhttp://en.wikipedia.org/wiki/Piezoelectricity#cite_note-36http://en.wikipedia.org/wiki/Intracytoplasmic_sperm_injectionhttp://en.wikipedia.org/wiki/Total_fertilization_failurehttp://en.wikipedia.org/wiki/Piezoelectricity#cite_note-35http://en.wikipedia.org/wiki/Tennis_rackethttp://en.wikipedia.org/wiki/Head_%28company%29http://en.wikipedia.org/wiki/Germanyhttp://en.wikipedia.org/wiki/Darmstadt_University_of_Technologyhttp://en.wikipedia.org/wiki/Frankfurt


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Potential applications

Photovoltaics:

The efficiency of a hybridphotovoltaic cell that contains piezoelectric materials can be

increased simply by placing it near a source of ambient noise or vibration. The effect was

demonstrated with organic cells using zinc oxide nanotubes. The electricity generated by the

piezoelectric effect itself is a negligible percentage of the overall output. Sound levels as low as

75 decibels improved efficiency by up to 50 percent. Efficiency peaked at 10 kHz, the resonant

frequency of the nanotubes. The electrical field set up by the vibrating nanotubes interacts with

electrons migrating from the organic polymer layer. This process decreases the likelihood of

recombination, in which electrons are energized but settle back into a hole instead of migrating

to the electron-accepting ZnO layer.[39][40]
http://en.wikipedia.org/wiki/Photovoltaic_cellhttp://en.wikipedia.org/wiki/Zinc_oxidehttp://en.wikipedia.org/wiki/Piezoelectricity#cite_note-39http://en.wikipedia.org/wiki/Piezoelectricity#cite_note-39http://en.wikipedia.org/wiki/Piezoelectricity#cite_note-39http://en.wikipedia.org/wiki/Piezoelectricity#cite_note-39http://en.wikipedia.org/wiki/Piezoelectricity#cite_note-39http://en.wikipedia.org/wiki/Zinc_oxidehttp://en.wikipedia.org/wiki/Photovoltaic_cell

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