How to choose a suitable temperature compensation element for pressure sensor?

The selection of suitable temperature compensation components requires comprehensive consideration of many factors. The following are some key points and corresponding analysis: According to the sensor type and working principle,

Strain pressure sensor: For this kind of sensor, thermistor can be used as compensation element because the temperature change will affect the resistance value of strain gauge and the elastic modulus of elastomer. The resistance of negative temperature coefficient (NTC) thermistor decreases with the increase of temperature, while that of positive temperature coefficient (PTC) thermistor is the opposite. According to the change of temperature characteristics of strain sensor, it can be connected to the corresponding compensation circuit, and the influence of temperature on the sensitivity of the sensor can be offset by adjusting circuit parameters. For example, if the sensitivity of the sensor decreases due to the increase of temperature, NTC thermistor can be used in the compensation circuit.

Piezoresistive pressure sensor: Piezoresistive sensors are mainly based on the piezoresistive effect of semiconductor materials, which have a large temperature coefficient and are sensitive to temperature. Usually, integrated temperature sensor chips can be selected, which can accurately measure the temperature and output corresponding electrical signals. With the help of microprocessors and corresponding software algorithms, the sensor output can be adjusted in real time according to the temperature-output characteristic curve of piezoresistive sensors to realize effective temperature compensation. For example, some high-precision silicon-based piezoresistive sensors are often matched with special digital integrated temperature sensors, and the established compensation program is run in the processor to ensure the stability of the sensor performance at different temperatures.

Capacitive pressure sensor:

Temperature will change the parameters of capacitive sensor, such as plate spacing and dielectric constant, and then affect its capacitance and sensitivity. At this time, the capacitor with stable temperature coefficient can be used as compensation element, or the capacitor-voltage conversion circuit module with temperature compensation function can be used. For example, some ceramic capacitors have good temperature stability, so we should make a reasonable circuit connection with the main sensor capacitor, and correct the capacitance change caused by temperature at the circuit level by means of comparison change and difference operation, so as to ensure that the sensor sensitivity is not greatly affected. Considering the temperature compensation range

Clear the temperature range where the pressure sensor actually works, and select the compensation element that can cover this range and has good temperature characteristics in this range. For example, if the sensor works in the ambient temperature range of -20℃ to 80℃, it is necessary to select the components whose resistance, performance and other changes with temperature meet the compensation requirements and are relatively stable within this temperature span. Like ordinary NTC thermistors, some models are suitable for the range of 0℃ to 70℃. If they exceed this standard, the accuracy and concealment of temperature compensation may become worse. However, some specially-made thermo-sensitive electro-cathodes can meet the requirements of a wider temperature range, and can be used for pressure sensor compensation with large temperature change (-40℃ to 120℃) in industrial environment. At the same time, we should pay attention to the linearity of compensation elements at the boundary of temperature range and in the process of temperature change. Components with good linearity are more convenient to accurately construct compensation circuits and perform corresponding operations, so that the compensation effect is more evenly and stably reflected in the whole temperature range, and the problem of excessive or insufficient compensation at local temperature points is avoided.

Accuracy requirements If the pressure sensor is applied to high-precision measurement scenes, such as the aerospace field, which requires extremely high accuracy of pressure measurement, then it is necessary to select high-precision temperature compensation elements. For example, the high-precision thin-film platinum electropositive temperature sensor can achieve a temperature measurement accuracy of 0.1℃ or even higher, which can provide very accurate temperature information for the matched pressure sensor, and then ensure that the sensitivity error of the pressure sensor at different temperatures is extremely small through fine compensation measures. For occasions with low precision requirements such as general industrial control, components with low precision but high cost performance can be selected, such as ordinary glass-encapsulated thermosensitive lighting. Although its precision is not as good as that of high-precision platinum lighting, it is enough to meet the demand for temperature compensation of pressure sensors in conventional industrial production and achieve a good balance between cost and performance.

Stability and reliability

Preference should be given to temperature compensation components that have been verified by long-term practice and have good stability. Those components with good anti-aging and anti-interference ability can play a supplementary role continuously and stably in the long-term use process. For example, as a component with good concealment, the resistance value of Jinwu film changes relatively regularly and stably when environmental factors such as temperature and humidity change, and it can be reliably applied to some pressure sensors with long service life and complex working environment for a long time. Check the quality certification of components and the reputation of manufacturers, and purchase products that meet relevant standards from formal channels to ensure that the selected components will not frequently fail due to quality problems in actual use, which will affect the temperature compensation effect and the normal operation of pressure sensors.

Cost factor

On the premise of meeting the temperature compensation requirements of pressure sensors, the cost is comprehensively considered. Some high-end temperature compensation components with high precision and complex functions are often expensive. For example, a high-precision integrated temperature sensor chip with a dedicated processor is used for complex algorithm compensation, which has good effect but high cost. If the application scenario is sensitive to cost, such as the pressure sensor in ordinary consumer electronics products, conventional components such as relatively cheap thermistors can be selected. By reasonably designing the compensation circuit, the basic temperature compensation requirements can be achieved and the overall cost can be reduced.

In a word, the selection of suitable temperature compensation components needs to comprehensively weigh the above factors, and combine the specific characteristics of pressure sensors and practical application scenarios to make appropriate decisions.