IDK

• Piezoelectricity


  The electric charge that accumulates in certain solid materials in response to applied mechanical stress
• Piezoelectric effect

  • Linear electromechanical interaction between the mechanical and electrical states in crystalline materials with no inversion symmetry
  • Reversible process: materials exhibiting the piezoelectric effect also exhibit the reverse piezoelectric effect
• Piezoelectric materials

  • Crystals
  • Certain ceramics
  • Biological matter such as bone, DNA, and various proteins
• Reverse piezoelectric effect

  Internal generation of a mechanical strain resulting from an applied electric field
• Piezoelectric materials

  • Lead zirconate titanate crystals
• Piezoelectric materials


  • Generate measurable piezoelectricity when their static structure is deformed by about 0.1% of the original dimension
  • Change about 0.1% of their static dimension when an external electric field is applied
• Inverse piezoelectric effect

  Used in the production of ultrasound waves
• Applications of piezoelectric effect

  • Production and detection of sound
  • Piezoelectric inkjet printing
  • Generation of high voltage electricity
  • Clock generator in electronic devices
  • Microbalances
  • Ultrasonic nozzle
  • Ultrafine focusing of optical assemblies
  • Scanning probe microscopes
  • Pickups of some electronically amplified guitars
  • Triggers in most modern electronic drums
  • Generating sparks to ignite gas cooking and heating devices, torches, and cigarette lighters
• Mechanism of piezoelectric effect

  • Closely related to the occurrence of electric dipole moments in solids
  • Dipole density or polarization may be calculated for crystals by summing up the dipole moments per volume of the crystallographic unit cell
  • Dipoles near each other tend to be aligned in regions called Weiss domains
  • Domains can be aligned using the process of poling
• Not all piezoelectric materials can be poled
• Importance of piezoelectric effect

  • Change of polarization P when applying a mechanical stress
  • Change in P appears as a variation of surface charge density upon the crystal faces, i.e. as a variation of the electric field extending between the faces caused by a change in dipole density in the bulk
• A 1 cm3 cube of quartz with 2 kN (500 lbf) of correctly applied force can produce a voltage of 12500 V
• Converse piezoelectric effect

  Application of an electrical field creates mechanical deformation in the crystal
• Piezoelectric materials

  Have the unique and useful property of being able to transform mechanical energy into electrical energy, and vice versa
• Applications of piezoelectric materials


  • Sensors and actuators
  • Artificial muscles
  • Energy harvesting
• Currently available piezoelectric materials and methods are unable to produce a sufficient amount of energy, so engineers are researching how to improve piezoelectric energy harvesting devices
• Equation to calculate energy stored in a capacitor


  E = 1/2 * C * V^2
• Very little energy is stored in piezoelectric generators, generally around 0.00001 joules, compared to a cell phone battery which stores around 18,000 joules
• Approaches to improve piezoelectric energy harvesting


  • Improve the piezoelectric material itself to be more efficient at converting mechanical energy into electrical energy
  • Place the material where it will be deformed (or tapped) very rapidly
• Piezoelectric generator


  A device that converts mechanical energy into electrical energy using the piezoelectric effect
• Common piezoelectric materials


  • Quartz
  • Rochelle salt
  • Lead zirconate titanate (PZT)
  • Certain ceramics
• Working principle of piezoelectric generator


  1. Mechanical stress applied to piezoelectric material causes crystal lattice deformation

  2. Separation of positive and negative charges creates voltage potential and electric field
• Applications of piezoelectric generators


  • Energy harvesting
  • Sensors
  • Actuators
  • Electronic components
• Piezoelectric generators


  • Suitable for powering low-power electronic devices or sensors
  • Have a high power density
  • Have a quick response time
  • Can efficiently convert mechanical energy into electrical energy
• Challenges of piezoelectric generators


  • Amount of power generated is generally small, limiting their use in high-power applications
  • Efficiency of energy conversion is influenced by factors such as the frequency and amplitude of the mechanical vibrations
• Frequency considerations


  Piezoelectric generators operate most efficiently at specific frequencies that match their resonant frequency
• Ongoing research aims to improve the efficiency and scalability of piezoelectric generators, and integrate them with other energy harvesting technologies
• Potential future applications


  Powering small electronic devices in remote or hard-to-reach locations, where traditional power sources are impractical