Piezoelectric sensor

[citation needed] Even though piezoelectric sensors are electromechanical systems that react to compression, the sensing elements show almost zero deflection.

This gives piezoelectric sensors ruggedness, an extremely high natural frequency and an excellent linearity over a wide amplitude range.

Additionally, piezoelectric technology is insensitive to electromagnetic fields and radiation, enabling measurements under harsh conditions.

Some materials used (especially gallium phosphate or tourmaline) are extremely stable at high temperatures, enabling sensors to have a working range of up to 1000 °C.

Tourmaline shows pyroelectricity in addition to the piezoelectric effect; this is the ability to generate an electrical signal when the temperature of the crystal changes.

While quartz sensors must be cooled during measurements at temperatures above 300 °C, special types of crystals like GaPO4 gallium phosphate show no twin formation up to the melting point of the material itself.

Piezoelectric sensors can also be used to determine aromas in the air by simultaneously measuring resonance and capacitance.

Computer controlled electronics vastly increase the range of potential applications for piezoelectric sensors.

[8][9] Piezoelectricity has also been shown in the collagen of soft tissue such as the Achilles tendon, aortic walls, and heart valves.

Putting several elements mechanically in series and electrically in parallel is the only way to increase the charge output.

C0 represents the static capacitance of the transducer, resulting from an inertial mass of infinite size.

The main difference in working principle between these two cases is the way they apply forces to the sensing elements.

This is accomplished by using piezoelectric materials to convert mechanical strain into usable electrical energy.

The less-sensitive, natural, single-crystal materials (gallium phosphate, quartz, tourmaline) have a higher – when carefully handled, almost unlimited – long term stability.

Thin film piezoelectric materials can be manufactured utilizing sputtering, CVD (chemical vapour deposition), ALD (atomic layer epitaxy) etc.

[18] In this process, the piezoelectric particles are dispersed into the aluminum matrix, creating a composite material capable of both structural and sensing functions.

The piezoelectric particles generate an electrical signal in response to mechanical stress or strain,[19] enabling the material to monitor its own condition.

FSP ensures a fine dispersion of the piezoelectric phase and enhances the bonding between particles and the matrix, leading to improved mechanical and sensing properties.

A piezoelectric disk generates a voltage when deformed (change in shape is greatly exaggerated)
Figure 1. Frequency response of a piezoelectric sensor; output voltage over applied force versus frequency
Figure 2. Schematic symbol and circuit incorporating the mechanical–electrical analogy for a piezoelectric sensor
Figure 3. In the flat region, the sensor can be modeled as a voltage source in series with the sensor's capacitance or a charge source in parallel with the capacitance
Metal disks with piezo material, used in buzzers or as contact microphones