The pressure sensor is a kind of pressure that can be used in the fields of steel and chemical industry. It can be used with the pressure regulator to realize automatic pressure control. Diffused silicon pressure sensors may have been heard, but do you know the principle of diffused silicon pressure sensors? The following small series will be introduced for everyone. I. Introduction and principle of diffused silicon pressure sensor The diffusion silicon pressure sensor utilizes the principle of piezoresistive effect, adopts integrated process technology to dope and diffuse, and forms a strain resistance along the characteristic crystal orientation on the single crystal silicon wafer to form a Wheatstone bridge. By using the elastic mechanical properties of silicon materials and performing anisotropic micromachining on the same silicon-cut material, a diffused silicon sensor integrating force-sensitive and force-electric conversion detection is fabricated. The pressure of the diffused silicon pressure sensor acts directly on the diaphragm of the sensor (stainless steel or ceramic), causing the diaphragm to produce a micro-displacement proportional to the pressure of the medium, causing a change in the resistance of the sensor, and detecting this change with an electronic circuit. And convert and output a standard measurement signal corresponding to this pressure. Second, the characteristics of diffused silicon pressure sensor 1, suitable for making small range sensors The piezoresistive effect of the silicon-type force-sensitive resistor has no dead zone in the low-range section near the zero point, and the range of the pressure sensor can be as small as several Kpa. 2, high output sensitivity The sensitivity factor of silicon strain resistance is 50-100 times higher than that of metal strain gauges, so the sensitivity of the corresponding sensor is very high, and the general range output is about 100mv. Therefore, there is no special requirement for the interface circuit, and it is convenient to use. 3, high precision Since the sensor's perception, sensitive conversion and detection are realized by the same component, there is no intermediate conversion link, and the repeatability and hysteresis error are small. Since the single crystal silicon itself has a large rigidity and a small deformation, a good linearity is ensured. 4. Due to the low single-strain deformation of the work, the maximum displacement of the elastic chip is on the order of submicron, so there is no wear, no fatigue, no aging, and the service life is up to 1×103 pressure cycle, and the performance is stable and the reliability is high. 5. Due to the excellent chemical corrosion resistance of silicon, even non-isolated diffused silicon pressure sensors have a considerable degree of adaptability to various media. 6. Because the chip adopts integrated process and no transmission parts, it is small in size and light in weight. Third, the performance parameters of CKY-204 diffusion silicon pressure sensor Measuring medium: Various liquid, gas or steam range compatible with 316L stainless steel: -100 kPa~0~2kPa...60MPa Pressure mode: gauge pressure, absolute pressure, sealing pressure Constant voltage supply: 10VDC recommended, maximum 15VDC Constant current supply: 1.5mA recommended, up to 4mA Bridge resistance: 4000Ω (typical) Comprehensive accuracy: 0.1% FS, 0.3% FS, 0.5% FS optional Temperature drift: 0.02% FS / ° C Time drift: ≤0.2%FS/year Compensation temperature: 0～80°C Medium temperature: -40 to 125 ° C Ambient temperature: -40 to 85 °C. Fourth, the use of diffused silicon pressure sensor considerations 1. Temperature compensation, diffusion silicon pressure sensor is a semiconductor, semiconductor has strong temperature characteristics, no temperature compensation, measurement error may be relatively large. 2, diffusion silicon pressure sensor sensing diaphragm is only a few dozen meters thick, must not touch. 3. The power supply voltage should be stable. The inside of the sensor is actually a bridge. The fluctuation of the power supply voltage will cause the bridge output to change, which will affect the measurement accuracy. 4. To be used within the rated voltage, overvoltage can cause damage to the sensor. 5. Do not short circuit the output. V. Diffusion silicon pressure sensor selection 1. Selection of sensor and transmitter: According to the nature of the pressure measured by the user, the user should first determine the gauge pressure (relative to the local atmospheric pressure), differential pressure, absolute pressure or negative pressure. If you are measuring the level, make sure that there is free atmospheric pressure above the level or sealed container pressure. If you measure the liquid level in a sealed pressure vessel, you should use a differential pressure product. 2. Determination of product range: From the absolute safety considerations of the product, it is generally preferred to make the working pressure value 60%-80% of the standard range value. The overload pressure caused by abnormal conditions may occur in the whole measurement system. The maximum overload. When measuring the fluid pressure of the dynamic pipeline, the liquid hammer, the air hammer effect, the impact pressure, and the product load should be appropriately increased. 3. Product accuracy selection: Users can request various parameters and a single parameter accuracy index according to the detected working conditions, so as to use the applicable accuracy requirements. The three precision indicators given by the product are calculated using the international least squares method or the end-base translation method. When using a sensor. The accuracy level determination should be based on the maximum error option assigned to the sensor by the measurement system. Additional errors introduced by the zero time drift, zero and full temperature coefficients should sometimes be considered. 4. Select the temperature range of the product: The transmitter performs comprehensive temperature compensation after assembling the circuit. For users with wide temperature range and high total accuracy, it can also be executed by software in secondary instrument data processing. Temperature error correction. Exceeding the compensation zone, the temperature coefficient indicator may exceed the standard, but it can still be used. Long-term operation in the temperature limit zone will affect the service life of the product. 5. Selection of differential pressure sensor: Differential pressure type sensor is usually used in the case of positive pressure difference between high pressure end pressure and low pressure end pressure. Although diffused silicon sensor can also be used for negative differential pressure, generally the two pressure ends are basically symmetrical. However, the negative pressure end is generally not calibrated. If the user requires high symmetry of the two pressure ends, special notice is required. 6. Frequency response characteristics: The natural frequency of the diffused silicon sensor is higher than that of other products. In addition, more cases are caused by the influence of the structural parameters of the pressure-sensing cavity of the sensor structure and the size of the rigid body of the sensor structure. The latter is impossible. The length is limited, so it is mainly affected by the pressure chamber and the pressure hole. 7. Matching with the measured medium: The sensor interface and the electronic housing are produced from a variety of different structural materials. With different media compatibility, in order to obtain the best use effect, the product will not be damaged due to media mismatch. The user should understand the exact name, concentration and temperature of the media when selecting the order. If the above items still do not meet the special requirements of the user. Sixth, the application of diffusion silicon pressure sensor Diffused silicon pressure sensors are mainly used in heating, refrigeration, chemical, coal, petroleum, food processing, water supply and other industries. It can be said that any industry with higher automation requirements may use diffused silicon pressure sensors. Due to the nature of the diffused silicon sensor itself, it cannot be used for the measurement of high temperature and low temperature media. Twinkle System Technology Co Ltd , https://www.pickingbylight.com