Zero drift of pressure sensors

causeThere are several main reasons for the zero drift of pressure sensors:

1. There are bubbles or impurities in the adhesive layer of the strain gauge

2. The performance of the strain gauge itself is unstable

3. There are faulty solder joints in the circuit

4. Incomplete stress release of elastomers; In addition, it is also related to many factors such as magnetic field, frequency, temperature, etc. Electric drift or some drift can exist, but we can narrow its range or correct it in some ways.

Zero point thermal drift is an important indicator that affects the performance of pressure sensors and has received widespread attention. Internationally, it is believed that the zero point thermal drift only depends on the inequality and temperature nonlinearity of the force sensitive resistor. In fact, the zero point thermal drift is also related to the reverse leakage of the force sensitive resistor. At this point, polycrystalline silicon can absorb heavy metal impurities from the substrate, thereby reducing the reverse leakage of the force sensitive resistor, improving the zero point thermal drift, and improving the performance of the sensor.

What are the other ways to reduce and correct electrical drift?

Besides affecting the measurement accuracy and reducing sensitivity of pressure sensors, what other important effects does zero drift have?

The so-called zero drift refers to the phenomenon of irregular and slow changing voltage at the input end of an amplifier when the input end is short circuited. The main reasons for zero drift are the influence of temperature changes on transistor parameters and fluctuations in power supply voltage. In most amplifiers, the zero drift of the front stage has the greatest impact. The more stages and amplification factors, the more severe the zero drift.

The magnitude of drift mainly depends on the selection of strain materials, and the structure or composition of the materials determine their stability or thermal sensitivity. The processing and production of selected materials are also important. Different processes can produce different strain values, and the key lies in the stability of the bridge value or changes in the process law after some aging and other adjustments. There are many methods for adjusting drift, mostly determined by the manufacturer's conditions or production needs. Nowadays, most manufacturers have good control over zero drift. Temperature regulation can be compensated and aged through internal temperature resistance and heating zero sensitivity resistance. For transformers that use circuit conversion, the drift in the circuit can be compensated by selecting good components and designing more suitable circuits.

Strain materials should be selected with high sensitivity coefficient and small temperature changes.