Thread Content
Pressure sensors are the most commonly used type of sensor in industrial applications. The pressure sensors we use typically rely on the piezoelectric effect to function, and such sensors are also known as piezoelectric sensors. We know that crystals are anisotropic, while amorphous materials are isotropic. In certain crystalline media, a polarization effect occurs when they are deformed under mechanical force applied in a specific direction ； When the mechanical force is removed, it returns to its uncharged state; that is, when under pressure, certain crystals may produce an electrical effect, which is known as the polarization effect. It is based on this effect that scientists developed pressure sensors. The main piezoelectric materials used in piezoelectric sensors include quartz, potassium sodium tartrate, and ammonium dihydrogen phosphate. Quartz (silicon dioxide) is a natural crystal, and the piezoelectric effect was discovered in this crystal. The piezoelectric properties remain within a certain temperature range, but they disappear completely once the temperature exceeds that range (this high temperature is known as the \"Curie point\"). Since the electric field changes only slightly with stress variations (in other words, the piezoelectric coefficient is relatively low), quartz has gradually been replaced by other piezoelectric crystals. Sodium potassium tartrate has high piezoelectric sensitivity and piezoelectric coefficients, but it can only be used in environments with room temperature and low humidity. Dihydrogen ammonium phosphate is a synthetic crystal that can withstand high temperatures and relatively high humidity, which is why it has been widely used. Today, the piezoelectric effect is also applied to polycrystals, such as modern piezoelectric ceramics including barium titanate piezoelectric ceramics, PZT, niobate-based piezoelectric ceramics, lead niobate magnesium titanate piezoelectric ceramics, and so on. The piezoelectric effect is the main working principle of piezoelectric sensors. These sensors cannot be used for static measurements, as the charge generated by an external force can only be retained when the circuit has an infinitely high input impedance. The actual situation is not like this; therefore, this means that piezoelectric sensors can only measure dynamic stress. Piezoelectric sensors are mainly used in the measurement of acceleration, pressure, force, etc. A piezoelectric acceleration sensor is a commonly used accelerometer. It boasts excellent features such as a simple structure, small size, light weight, and long service life. Piezoelectric acceleration sensors have been widely used in the measurement of vibration and shock in aircraft, automobiles, ships, bridges, and buildings, and they hold a particularly important role, especially in the fields of aviation and aerospace. Piezoelectric sensors can also be used to measure the combustion pressure inside the engine as well as the vacuum level. It can also be used in **industry, for example to measure the changes in chamber pressure and the shock wave pressure at the muzzle at the moment a gun is fired**. It can be used to measure both high pressures and very low pressures. Piezoelectric sensors are also widely used in biomedical measurements; for example, ventricular catheter microphones are made from piezoelectric sensors. Since measuring dynamic pressure is such a common task, piezoelectric sensors have a very wide range of applications. In addition to piezoelectric sensors, there are also piezoresistive sensors made using the piezoresistive effect, as well as strain sensors that utilize the strain effect. These various pressure sensors rely on different effects and materials, allowing them to serve their unique purposes in different applications