Comparison of Characteristics of Strain, Piezoresistive, and Piezoelectric Sensors

Comparison of Characteristics of Strain, Piezoresistive, and Piezoelectric Sensors

1Strain gauge sensor

Strain gauge sensors convert changes in force into changes in resistance values for measurement. Strain gauges are resistance bodies made of metal conductors or semiconductors, and their resistance values change with the strain generated by the force. The strain effect is a phenomenon where the resistance value of a conductor changes when subjected to mechanical deformation.

2Piezoresistive sensor

The sensitivity of piezoresistive sensors is higher than that of metal wire strain gauges, with good accuracy, good response frequency, and reliable operation. The disadvantage is that it is greatly affected by temperature, and temperature compensation should be carried out. The piezoresistive effect is a phenomenon where the resistivity of a material changes when it deforms under external forces.

3Piezoelectric sensor

The principle of piezoelectric sensors is based on the piezoelectric effect of certain crystal materials. Currently, widely used piezoelectric materials include quartz and barium titanate. When these crystals undergo mechanical deformation under pressure, opposite charges are generated on their opposite sides, which is called& Ldquo; Piezoelectric effect; Rdquo;.

Piezoelectric pressure sensors cannot be used for static measurement, they are generally used for measuring pulsating pressure and cannot measure static pressure; The signal generated by a piezoelectric sensor is weak and the output impedance is high. It is necessary to amplify the weak signal through voltage or charge amplification (usually charge amplification) according to the output requirements of the piezoelectric sensor, and transform the high output impedance into low output impedance in order for this signal to be accepted by an oscilloscope or other secondary instruments.

The Differences and Advantages and Disadvantages between Piezoelectric Sensors and Piezoresistive Sensors

The front one is affected by the electric field, while the back one is affected by the temperature. It depends on which occasion you use it in. The principle of the former is the piezoelectric effect, while the principle of the latter is the strain after being subjected to force.

The disadvantage of the former is charge leakage, while the advantage is its simple structure, high sensitivity, and signal-to-noise ratio.

The disadvantage of the latter is that the signal-to-noise ratio is not high, and the structure is more complex than the former. The advantages are cheap, durable, and good frequency response.

Piezoresistive sensors are devices made by diffusing resistance on semiconductor substrates based on the piezoresistive effect of semiconductor materials. The substrate can be directly used as a measuring sensing element, and the diffusion resistance is connected to the substrate in the form of an electric bridge. When the substrate undergoes deformation due to external forces, the resistance values will change, and the bridge will produce corresponding unbalanced output.

The substrate (or membrane) materials used for piezoresistive sensors are mainly silicon wafers and germanium wafers. Silicon piezoresistive sensors made of silicon wafers as sensitive materials are receiving increasing attention, especially solid-state piezoresistive sensors that measure pressure and velocity.

Piezoelectric sensor: A sensor based on the piezoelectric effect. It is a type of self generating and electromechanical conversion sensor. Its sensitive components are made of piezoelectric materials. Piezoelectric materials generate surface charges when subjected to force. After being amplified and impedance transformed by a charge amplifier and measuring circuit, this charge becomes directly proportional to the output of the external force applied. Piezoelectric sensors are used to measure non electrical physical quantities such as pressure, acceleration, etc. that convert force and energy into force (see Piezoelectric pressure sensors, accelerometers). Its advantages include wide frequency band, high sensitivity, high signal-to-noise ratio, simple structure, reliable operation, and light weight. The disadvantage is that some piezoelectric materials require moisture-proof measures, and the output DC response is poor, requiring the use of high input impedance circuits or charge amplifiers to overcome this defect. The emergence of supporting instruments and low noise, small capacitance, and high insulation resistance cables makes the use of piezoelectric sensors more convenient. It is widely used in technical fields such as engineering mechanics, biomedicine, and electroacoustics.