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Working Principle and Applications of Monocrystalline Silicon Differential Pressure Sensors
In modern industrial measurement, differential pressure sensors are essential instruments. Monocrystalline silicon differential pressure sensors, known for exceptional accuracy, stability, and reliability, are preferred for high-end applications. They are widely used in petrochemical, industrial automation, pharmaceutical, environmental, and medical equipment, providing reliable data for process control and safety monitoring.
Working Principle of Monocrystalline Silicon Differential Pressure Sensors
The core principle is the piezoresistive effect of silicon. When monocrystalline silicon experiences mechanical stress, carrier mobility and concentration change, resulting in a significant variation in resistance.
Specific working process:
Pressure applied to the diaphragm: The pressure difference (ΔP) of the measured medium acts on the sensor's isolation diaphragm (usually 316L stainless steel) and is transmitted evenly to the monocrystalline silicon sensing chip via internal silicone oil.
Micro-deformation of the silicon diaphragm: The chip integrates a Wheatstone bridge of piezoresistive elements. Small diaphragm deformations increase resistance in tension areas and decrease resistance in compression areas, unbalancing the bridge.
Electrical signal output: Under constant current or voltage excitation, the bridge outputs a millivolt-level differential voltage proportional to the pressure difference, with high linearity.
Signal processing and standardization: The millivolt signal is amplified, temperature-compensated, and linearized internally, then output as standard industrial signals, such as 4-20mA, 0-5V/0-10V, or digital signals (HART, Modbus).
This material-based measurement method provides high sensitivity, excellent repeatability, and long-term stability.
Sensor Structure and Key Technologies
Manufactured using MEMS microelectromechanical systems technology, the core chip is made from monocrystalline silicon wafers using microfabrication techniques. Typical components include:
Sensing chip: piezoresistive bridges formed by diffusion or ion implantation on silicon substrate
Isolation diaphragm: 316L stainless steel or Hastelloy, corrosion-resistant and high-temperature resistant
Silicone oil fill: transmits pressure while protecting the chip from direct medium contact
Full welded seal: no O-ring, prevents leakage, ensures long-term stability
Compared with traditional metal strain or ceramic capacitive sensors, monocrystalline silicon solutions have significant advantages:
Higher measurement accuracy (typically ±0.075% FS or better)
Lower temperature drift (excellent products ±0.01%/°C)
Compact and lightweight, easy to integrate
High overload capacity (3–10 times full scale)
Fast response (millisecond level)
Main Applications
Due to high accuracy and environmental adaptability, monocrystalline silicon differential pressure sensors are widely used in key industries:
1. Petrochemical and Oil & Gas
Used for pipeline differential pressure monitoring, filter clog detection, reactor pressure control, liquid level measurement, and flow calculation (via differential pressure method), performing well in high temperature, high pressure, and corrosive environments.
2. Industrial Automation and Process Control
Applied in liquid level, flow, and density measurements, as well as pump/valve control systems. Ideal for high-precision, long-term stable DCS/PLC system integration.
3. Pharmaceutical and Food & Beverage
GMP-compliant, used for cleanroom differential pressure monitoring, filter status assessment, and fermentation tank pressure control. Resistant to cleaning and high-temperature sterilization.
4. Environmental and Water Treatment
For atmospheric pressure differential measurement in meteorological stations, liquid level/pressure detection in water quality monitoring, and pressure control in aeration systems of wastewater treatment plants.
5. Medical Equipment
Applications include airway pressure monitoring in ventilators, blood pressure measurement, and respiratory flow measurement, requiring miniaturization, high precision, and biocompatibility.
Selection and Usage Considerations
Key parameters to consider when choosing:
Range and overload capacity
Accuracy grade and temperature compensation range
Output signal type (analog/digital)
Medium compatibility (isolation diaphragm material)
Explosion-proof rating (Ex d IIC T6 / Ex ia)
Installation method (flange, threaded, sanitary)
Correct installation and maintenance are critical for long-term accuracy: avoid shocks, ensure medium isolation, and periodically calibrate zero points.
Conclusion
Monocrystalline silicon differential pressure sensors leverage the piezoresistive effect and MEMS technology to achieve high precision and reliability, setting a benchmark in modern industrial measurement. They meet the demands of high-precision process control and perform exceptionally in extreme environments and critical applications.
With Industry 4.0 and smart manufacturing advancements, these sensors will continue evolving toward higher accuracy, greater intelligence, and wider temperature ranges, providing reliable pressure measurement solutions across industries.
If you are seeking a stable, high-precision differential pressure solution, monocrystalline silicon technology deserves consideration and may be the optimal choice for your project.
