A piezoelectric sensor, also known as a piezoelectric transducer, is a device that uses the piezoelectric effect to measure changes in pressure, acceleration, temperature, strain or force by converting these into an electrical charge. The prefix piezo is Greek for press or squeeze. The ability of piezoelectric material to convert mechanical stress into electrical charge is called a piezoelectric effect. Generated piezoelectricity is proportional to the pressure applied to solid piezoelectric crystal materials.
Two main sensing materials used for piezoelectric sensors are piezoelectric ceramics (such as PZT ceramic) and single-crystal materials (such as quartz). The sensitivity of ceramic materials is higher than that of natural single-crystal materials, but their high sensitivity degrades over time.
Natural single-crystal materials (quartz, gallium-phosphate, tourmaline, etc) are less sensitive but have higher stability. A commonly-available quartz piezoelectric sensor (without enclosure) is shown in Fig. 1.
There are also new single-crystal materials commercially available, such as lead-magnesium-niobate lead titanate (PMN-PT).
There are two types of piezoelectric sensors based on the lead connection design: lead type and pin type, as shown in Fig. 2. Their specifications are listed in Table I. Both are commonly available; choice depends on size and other specifications.