HOME > TECHNOLOGY > Piezoelectric

Classification of dielectrics

Polarization by the electric field

  • - Electronic polarization
  • - Ionic polarization
  • - Dipole polarization (spontaneous polarization)

Polarization by the electric field

  • - Electronic polarization
  • - Ionic polarization
  • - Space charge polarization

Temperature controlled spontaneous polarization

External electric field controlled spontaneous polarization

What is piezoelectric effect?

Piezoelectric Effect is the ability of certain materials to generate an electric charge in response to applied mechanical stress. They also have the opposite effect – the application of electric voltage produces mechanical strain in the materials. This effect makes piezoelectric materials effective in sensors and transducers used in the automotive and healthcare industries, and for environmental monitoring.

What is hifu?

High intensity focused ultrasound
The fundamental principle of hifu is analogous to using a magnifying glass to focus sunlight, generating burning heat.
Therapeutic applications use ultrasound to deliver heat or agitation into the body; much higher energies are used than in diagnostic ultrasound.

Typical applications of Hifu is a skin lifting and tumor removing surgery.
Hifu lifting is a relatively new, innovative procedure that uses ultrasound technology to penetrate deeply into the skin, affecting a connective tissue layer called the SMAS. It utilizes highly focused ultrasound energy waves to tighten the SMAS layer of the skin at both the 3mm and 4mm depth. HIFU helps the body produce more collagen and the deep focused ultrasound produces tightening of the deep supportive connective tissue of the face. The explosive growth in future cosmetic and medical markets is expected.

Principle of Hifu (analogous to magnifying glass)

Temperature rising effect by focused ultrasound

Passive Sensor

suspension load sensors, airbag impact sensors and intruder alarms


When a object with mass accelerates, the force is generating (Newton’s second law, F=ma)

Knocking sensor

Knocking makes 6~20kHz vibration. Knocking sensor detects vibration and ECU control the ignition timing to suppress knocking.

Knocking : knocking in spark-ignition internal combustion engines occurs when combustion of the air/fuel mixture in the cylinder does not start off correctly in response to ignition by the spark plug, but one or more pockets of air/fuel mixture explode outside the envelope of the normal combustion front. High temperature and high pressure of detonation can cause damage of the cylinder parts or corrosion.


Piezoelectric spark igniter

Transducer and active sensor


Electrical energy → Mechanical energy (Generate ultrasonic wave)

Fuel level sensors and parking aid reverse sensors

Electrical energy → Mechanical energy (Generate ultrasonic wave)
Mechanical energy (Detect the returning ultrasonic wave) → Electrical energy
It is possible to detect the level of liquid when ultrasonic transducer is located at the bottom of tank


Valves for fuel injection systems devices for positioning headlamps and mirrors

Electrical energy → Mechanical displacement
Expansion → control valve close → Nozzle close
Contraction → control valve open → Nozzle open