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A piezoelectric disk generates a voltage when deformed (change in shape is greatly exaggerated) A piezoelectric sensor is a device that uses the piezoelectric effect to measure changes in pressure, acceleration, temperature, strain, or force by converting them to an electrical charge. The prefix piezo-is Greek for 'press' or 'squeeze'. [1]
A low impedance signal is advantageous because it can be transmitted across long cable lengths without a loss of signal quality. In addition, special low noise cables, which are otherwise required for use with piezoelectric sensors, are no longer necessary. The sensor circuit is supplied with constant current. A distinguishing feature of the ...
Some sensors require external voltage or current source of excitation, These sensors are called active sensors. (E.g. a temperature sensor like a thermistor & RTD, a pressure sensor (piezo-resistive and capacitive), etc.). The stability and precision of the excitation signal directly relates to the sensor accuracy and stability.
A parasitic effect of common coaxial sensor cables is a charge shift when the cable is bent. Even slight cable motion may produce considerable charge signals which cannot be distinguished from the sensor signal. Special low noise cables with a conductive coating of the inner isolation have been developed to minimize such effects.
The cross-section of a piezoelectric accelerometer. The word piezoelectric finds its roots in the Greek word piezein, which means to squeeze or press. When a physical force is exerted on the accelerometer, the seismic mass loads the piezoelectric element according to Newton's second law of motion (=). The force exerted on the piezoelectric ...
Detection of pressure variations in the form of sound is the most common sensor application, e.g. piezoelectric microphones (sound waves bend the piezoelectric material, creating a changing voltage) and piezoelectric pickups for acoustic-electric guitars. A piezo sensor attached to the body of an instrument is known as a contact microphone.
Working mechanism for piezoelectric devices with one end of the piezoelectric material is fixed. The induced piezopotential distribution is similar to the applied gate voltage in a traditional field-effect transistor, as shown in (b). Schematic diagram showing the three-way coupling among piezoelectricity, photoexcitation and semiconductor.
Active vibration isolation systems contain, along with the spring, a feedback circuit which consists of a sensor (for example a piezoelectric accelerometer or a geophone), a controller, and an actuator. The acceleration (vibration) signal is processed by a control circuit and amplifier.