Piezo-electric Transducer

• The Piezoelectric effect, is the ability of certain materials to generate an AC voltage when subjected to mechanical stress or vibration, or to vibrate when subjected to an AC voltage, or both.
• The most common Piezo-Electric material used is Quartz (Crystal).
• The piezoelectric transducer is used for the measurement of force, pressure, very small displacement, vibrations and sound waves. 

• The main principle of a piezoelectric transducer is that a force, when applied on the quartz crystal, produces electric charges on the crystal surface.
• The Piezoelectric transducer is also known to be mechanically stiff.
• The Piezoelectric Transducer can measure pressure in the same way a force or an acceleration can be measured.

Construction

• Mainly, it has the piezoelectric crystal.
• The piezoelectric crystal attached with some force summing members.

• When any pressure or force exerted on the crystal, it converts it into proportional output electrical signal.
• It is also known as inverse transducer due to its reverse inherent characteristics.
• If any electrical signal is supplied to crystal, it converts it into some physical movement.

Advantages

• Very high frequency response.
• Self-generating, so no need of external source.
• Simple to use as they have small dimensions and large measuring range.
• Barium titanate and quartz can be made in any desired shape and form. It also has a large dielectric constant. The crystal axis is selectable by orienting the direction of orientation.

• The piezoelectric transducer is used for dynamic measurement only.
• It has high temperature sensitivity.
• Some crystals are water soluble and get dissolve in high humid environment.

• Due to its excellent frequency response, it is normally used as an accelerometer, where the output is in the order of (1-30) mV per gravity of acceleration.
• The device is usually designed for use as a pre-tensional bolt so that both tensional and compression force measurements can be made.
• It can be used for measuring force, pressure and displacement in terms of voltage