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Topic: Piezoelectric effect


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In the News (Mon 19 Aug 19)

  
  Piezoelectric motor structures - Patent 4019073
The structure of the piezoelectric motor is determined by the arrangement of the piezoelectric device in the rotor and stator, the type of oscillation being excited, the shape of the piezoelectric device, the arrangement of its electrodes, their shape and electrical connection, as well as by the polarization of the piezoelectric material.
The piezoelectric device 8 of the last-mentioned vibrator 7 is in the form of a two-layer plate having an electrode 21 intermediate of the layers 22 of this piezoelectric device 8.
This is ensured by the two piezoelectric devices 8 of the stoator 2 being connected in parallel and arranged so that the directions of their polarization are symmetrical with respect to the plane BB perpendicular to the shaft 15 of the rotor 3 and extending intermediate of the piezoelectric devices 8 of the stator 2.
www.freepatentsonline.com /4019073.html   (15557 words)

  
 Piezoelectric Effect, Piezo Actuators, Motion Control Systems
Piezoelectricity is the ability of certain crystals to generate a voltage in response to applied mechanical stress.
The piezoelectric effect is reversible in that piezoelectric crystals, when subjected to an externally applied voltage, can change shape, or distort, by a small amount.
This distortion, which is approximately 0.1% of the size of the original piezoelectric crystal, is measured in nanometers, but nevertheless is sufficient to allow for useful application in a range of areas, such as precision motion applications and ultra fine focusing of optical assemblies.
www.nanomotion.com /piezoelectric.asp   (186 words)

  
 piezoelectric effect - HighBeam Encyclopedia   (Site not responding. Last check: 2007-11-03)
piezoelectric effect, voltage produced between surfaces of a solid dielectric (nonconducting substance) when a mechanical stress is applied to it.
Piezoelectric materials are used in transducers, e.g., phonograph cartridges, microphones, and strain gauges, which produce an electrical output from a mechanical input, and in earphones and ultrasonic radiators, which produce a mechanical output from an electrical input.
Piezoelectric solids typically resonate within narrowly defined frequency ranges; when suitably mounted they can be used in electric circuits as components of highly selective filters or as frequency-control devices for very stable oscillators.
www.encyclopedia.com /doc/1E1-piezoele.html   (288 words)

  
 Guide to the Piezoelectric Effect
Although the magnitudes of piezoelectric voltages, movements, or forces are small, and often require amplification (a typical disc of piezoelectric ceramic will increase or decrease in thickness by only a small fraction of a millimetre, for example) piezoelectric materials have been adapted to an impressive range of applications.
The inverse piezoelectric effect is used in actuation applications, such as in motors and devices that precisely control positioning, and in generating sonic and ultrasonic signals.
A traditional piezoelectric ceramic is a mass of perovskite crystals, each consisting of a small, tetravalent metal ion, usually titanium or zirconium, in a lattice of larger, divalent metal ions, usually lead or barium, and O2- ions.
www.pc-user.co.uk /piezoelectric_effect.htm   (889 words)

  
 PIEZOCRYST: Advanced Sensorics GmbH - Piezoelectric Sensors
Piezoelectric sensors rely on the piezoelectric effect, which was discovered by the Curie brothers in the late 19th century.
Longitudinal effect: The amount of charges produced is strictly proportional to the applied force and is independent of size and shape of the piezoelectric element.
In both piezoelectric pressure sensors (a) and piezoelectric accelerometers (b), the crystal elements are used in transversal mode.
www.piezocryst.com /piezoelectric_sensors.php   (1322 words)

  
 Piezoelectricity   (Site not responding. Last check: 2007-11-03)
Piezoelectric ceramic materials have found use in producing motions on the order of nanometers in the control of scanning tunneling microscopes.
The effect known as piezoelectricity was discovered by brothers Pierre and Jacques Curie when they were 21 and 24 years old in 1880.
This effect, called magnetostriction, is responsible for the familiar hum of transformers and other AC devices containing iron cores.
hyperphysics.phy-astr.gsu.edu /hbase/solids/piezo.html   (374 words)

  
 Ultrasound in Piezoelectric Media
Using this effect, a high-frequency alternating electric current can be converted to an ultrasonic wave of the same frequency, while a mechanical vibration, such as sound, can be converted into a corresponding electrical signal.
A thourough study is performed on the influence of piezoelectricity on the different modes of wave propagation.
The influence is calculated of an initial pressure, in the piezoelectric case and in the non-piezoelectric case, for homogeneous plane waves and also for inhomogeneous plane waves.
www.me.gatech.edu /declercq/Piezoelectric-Media.htm   (1226 words)

  
 ME 117/220 Lecture #6
Piezoelectricity is the name of a phenomenon which sounds as if it might be similar to piezoresistivity, but there is really very little in common between these two.
Piezoelectricity refers to a phenomenon in which forces applied to a segment of material lead to the appearance of electrical charge on the surfaces of the segment.
Piezoelectric coefficients have been tabulated for several materials (primarily those materials with large coefficients), and a table of coefficients is in the textbook.
www.yale.edu /eas996/smart/lect_6.html   (1338 words)

  
 [No title]   (Site not responding. Last check: 2007-11-03)
This effect is proportional to the deformation, which depends on the state of tension found in the corresponding material.
A material like quartz is considered piezoelectric because it has the ability to develop a net dipole moment if it is mechanically deformed in certain directions with respect to the atomic arrangement, and it is mechanically deformable by an electric field with an appropriate direction with respect to the atoms in the solid.
The Piezoelectric effect is an effect in which energy is converted between mechanical and electrical forms.
www.resonancepub.com /piezoele.htm   (1706 words)

  
 Materials by Design: Piezoelectric Materials   (Site not responding. Last check: 2007-11-03)
These materials are piezoelectric, and this phenomenon is known as the piezoelectric effect.
This phenomenon is known as electrostriction, or the reverse piezoelectric effect.
Piezoelectric materials are used in acoustic transducers, which convert acoustic (sound) waves into electric fields, and electric fields into acoustic waves.
www.mse.cornell.edu /courses/engri111/piezo.htm   (241 words)

  
 Channel Industries - Piezoelectric Ceramic
The piezoelectric effect is exhibited in a certain group of crystalline solid materials whose unit cells do not possess a center of symrnetry.
The piezoelectric constants are generally written with two subscripts, The first subscript is the electrical direction, and the second is the mechanical direction.
Piezoelectric ceramic materials are compounded to have advantageous properties depending upon their end use.
www.channelindustries.com /page03.htm   (603 words)

  
 Re: Reader about pyroelectric and piezoelectric crystals
Piezoelectricity refers to property that the polarization (or electric field) can be changed by mechanical perturbation of the structure.
PIEZOELECTRIC EFFECT: The piezoelectric effect is a linear, reversible electromechanical interaction occurring in materials possessing the proper symmetry properties.
The total pyroelectric coefficient measured at constant stress is the sum of the pyroelectric coefficients at constant strain (primary pyroelectric effect) and the piezoelectric contribution from thermal expansion (secondary pyroelectric effect).
www.madsci.org /posts/archives/aug97/871490370.Ph.r.html   (584 words)

  
 EEProductCenter.com :: Piezoelectric Technology: A Primer
Piezoelectric ceramics are used in myriad applications ranging from generating exquisitely controlled forces at the microscopic level to developing tremendous forces at the macro level.
Piezoelectric ceramics, and in particular PZT ceramic, are used in inexpensive but rugged sensors as well as multi-layer transformers for generating high voltages without any EMI.
This constant is known as the piezoelectric constant and is equal to the open circuit field developed per unit of applied stress or as the strain developed per unit of applied charge density or electric displacement.
www.eeproductcenter.com /showArticle.jhtml?articleID=192200838   (2430 words)

  
 Piezoelectric Materials- Global Technology Developments (Technical Insights):
Indirect Piezoelectric Effect:The converse of the direct piezoelectric effect is known as the indirect or inverse piezoelectric effect.
While the piezoelectric effect has been known to science for over 125 years, there has been a tremendous amount of research and advancement related to this sector in the last few years.
Piezoelectric materials presently find application in devices ranging from hydrospace to aerospace and with the increasing awareness of their benefits in the development and exploitation of smart materials and structures; industry participants forecast strong growth for these materials.
www.mindbranch.com /products/R1-4816.html   (829 words)

  
 Piezoelectric Contributions to Pulsed Degenerate Four-Wave Mixing
This is important because the possibility of piezoelectric relaxation introduces additional dependencies of the DFWM signal from the angle between the interacting beams and from the pulse-length.
The errors are estimated on the basis of a ~10% uncertainty in the dielectric and electro-optic tensors [8].
Their effect can only be seen as a dependence of the DFWM signal from the pulse length, or from the angle between the beams.
www.lehigh.edu /~ivb2/acoustic.html   (2053 words)

  
 Simulation of MEMS Piezoelectric Micropump for Biomedical Applications
This work is focused on a micropump driven by the piezoelectric effect, which in turn invokes the dominant resonance behavior. Because the design of the device is the emphasis of this study, the model was originated in CAD and includes the fine-scale geometric details commonly encountered in a wide variety of micropumps.
The piezoelectric component used in the current work is configured such that it deforms in the planar direction upon the application of a voltage across its thickness.
Figure 2 shows an exploded view of this micropump, including the Lead Zirconate Titanate (PZT) piezoelectric component, the thin diaphragm onto which the PZT is bonded, the square pumping chamber, and the two orifices that serve as channels for the inlet and outlet valves.
www.algor.com /news_pub/tech_white_papers/mems_micropump/default.asp   (3326 words)

  
 Bone electricity
Studies of the dielectric and piezoelectric properties of fully hydrated bone raise some doubt as to whether wet bone is piezoelectric at all at physiological frequencies (5.2).
Mechanical relaxation also occurs in piezoelectric materials and is important in applications: large damping is considered desirable in materials used to generate short acoustic pulses for flaw detection [8.10.6]; small damping (high mechanical Q) is desirable in stable resonators and high power transducers.
The role of gradient effects in the piezoelectricity of bone, IEEE Trans.
silver.neep.wisc.edu /~lakes/BoneElectr.html   (1706 words)

  
 Piezoelectric materials   (Site not responding. Last check: 2007-11-03)
The piezoelectric effect describes the relation between a mechanical stress and an electrical voltage in solids.
In physics, the piezoelectric effect can be described as the the link between electrostatics and mechanics.
The piezoelectric effect was discovered in 1880 by the Jacques and Pierre Curie brothers.
www.piezomaterials.com   (185 words)

  
 An Introduction to Transducer Crystals   (Site not responding. Last check: 2007-11-03)
Conversely, when a piezoelectric crystal is placed in an electric field, or when charges are applied by external means to its faces, the crystal exhibits strain, i.e.
Piezoelectric ceramics are more versatile in that their physical, chemical, and piezoelectric characteristics can be tailored to specific applications.
In both the direct and converse piezoelectric effects, the strain and stress are related to the electrical parameters by the piezoelectric constants, d
www.bostonpiezooptics.com /?D=6   (1469 words)

  
 Piezoelectric Effect
A piezoelectric crystal is connected to a light bulb.
Piezoelectric crystals are used in the strikers of lighters to generate a spark.
This was done to present the sound and the flash of the piezoelectric device.
jchemed.chem.wisc.edu /JCESoft/CCA/CCA2/MAIN/PIEZO/CD2R1.HTM   (296 words)

  
 The Piezoelectric Effect - R/C Crystals
What’s more, the piezoelectric effect works both ways: stress a piece of quartz and you get an electrical output from it that is proportional to the stress it undergoes.
That is to say, when the quartz has an electric field applied to it, the crystal becomes deformed or strained by an amount proportional to the applied field; the sense of the strain depends on the direction of the field.
Your old record player had a cartridge that used the piezoelectric effect, the ultrasonic transducers in your ancient car alarm used it, that hospital ultrasound scanner uses it, some gas and cigarette lighters use it.
www.favonius.com /soaring/crystals/crystals.htm   (1180 words)

  
 Piezoelectric Principle
One side of the piezoelectric material is connected to a rigid post at the sensor base.
By the piezoelectric effect a charge output proportional to the applied force is generated.
The piezoelectric element is connected to the sensor socket via a pair of electrodes.
www.mmf.de /piezoelectric_principle.htm   (514 words)

  
 Smart Materials
Piezoelectric materials have two unique properties which are interrelated.
Piezoelectric materials are most widely used as sensors in different environments.
An example of a piezoelectric material in everyday life is the airbag sensor in your car.
www.cs.ualberta.ca /~database/MEMS/sma_mems/smrt.html   (563 words)

  
 piezoelectric effect
In the 1950's, electrometer tubes of sufficient quality became available and the piezoelectric effect was commercialized.
Piezoelectric measuring devices are widely used today in the laboratory, on the production floor and as original equipment.
Quartz piezoelectric transducers consist essentially of thin slabs or plates cut in a precise orientation to the crystal axes depending on the application.
members.tripod.com /~albert51/maz.html   (663 words)

  
 [No title]   (Site not responding. Last check: 2007-11-03)
The piezoelectric effect is a phenomena resulting from a coupling between the electric and mechanical properties of a material.
Commercial applications of piezoelectric devices abound, for instance in speakers, spark generators inside electronic igniters, strain sensors pressure gages and as presice time-keepers in electronic clocks.
Because the force and displacement created by a pure piezoelectric material is relatively small, methods have been developed to allow amplification of the piezoelectric effect.
sxm4.uni-muenster.de /stm-en/Piezo.html   (500 words)

  
 Sensors
This chapter discusses the results of investigations into the piezoelectric sensors' response, their applicability to ambulation monitoring, implementation of the pressure transducers and results from other sensors which were briefly tested but not used.
Another method of using the piezoelectrics trialled was to place them under the in-sole in the shoe to measure pressure as weight is applied and removed from each foot (see Figure 6.3).
After much work with the piezoelectrics and attempts to extract concrete ambulation information from the signals, it was concluded that the piezoelectric sensors alone could not provide enough quantitative (and to an extent, even qualitative) information for the project's purposes.
www.csse.monash.edu.au /hons/projects/2000/Daniel.Willis/node8.html   (2347 words)

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