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Understanding the Technology and Types of Polysilicon Pressure Transmitters
Time：
2025-06-11
Polysilicon pressure transmitters are high-precision instruments widely used in industries such as oil and gas, chemical processing, power generation, and water treatment. Known for their accuracy, stability, and reliability, these transmitters use advanced silicon micro-machining and integrated sensor technologies. This article explores the working principles and common types of polysilicon pressure transmitters.
1. Working Principle of Polysilicon Pressure Transmitters
At the heart of a polysilicon pressure transmitter is a micromachined sensor made from a polysilicon semiconductor material. The core principle is based on piezoresistive sensing, where the electrical resistance of polysilicon changes when mechanical stress (caused by pressure) is applied.
Key Components:
Sensing Diaphragm: A thin silicon diaphragm deforms when pressure is applied.
Piezoresistive Elements: Implanted or diffused polysilicon resistors are integrated into the diaphragm in a Wheatstone bridge configuration.
Signal Conditioning Circuitry: Converts the resistance changes into a stable electrical output (commonly 4–20 mA or digital signals).
Operation Process:
Pressure applied to the diaphragm causes micro-deformation.
This deformation changes the resistance of the polysilicon elements.
The Wheatstone bridge circuit detects the imbalance and outputs a corresponding electrical signal.
The signal is amplified, compensated for temperature, and linearized by onboard electronics.
2. Advantages of Polysilicon Technology
High Sensitivity and Accuracy: Due to the stable piezoresistive effect in polysilicon.
Excellent Temperature Compensation: Integrated with on-chip temperature sensors.
Long-Term Stability: Minimal drift over time.
Compact and Robust: MEMS-based construction enables miniaturization and durability.
3. Types of Polysilicon Pressure Transmitters
a. Gauge Pressure Transmitters (GP)
Measures pressure relative to atmospheric pressure. Used in tanks, pipelines, and fluid distribution systems.
b. Absolute Pressure Transmitters (AP)
Measures pressure relative to a perfect vacuum. Suitable for applications requiring precise vacuum-level monitoring.
c. Differential Pressure Transmitters (DP)
Measures the pressure difference between two points. Commonly used for flow measurement, filter monitoring, and level sensing in pressurized vessels.
d. High-Pressure Transmitters
Designed for extreme pressure environments, such as hydraulic systems or high-pressure gas cylinders.
e. Smart Digital Pressure Transmitters
Incorporate digital communication protocols like HART, Modbus, or Profibus, enabling remote calibration, diagnostics, and integration into industrial control systems.
4. Application Scenarios
Oil and Gas Pipelines: For accurate monitoring of pressure fluctuations.
Chemical Processing Plants: Resistant to corrosion and capable of handling aggressive media.
Water and Wastewater Treatment: Ensure stable process control under fluctuating conditions.
Power Plants: Monitor boiler and steam pressures with high stability.
Conclusion
Polysilicon pressure transmitters represent a significant advancement in pressure sensing technology. Their combination of precision, reliability, and digital capabilities make them indispensable in modern industrial automation. As sensor integration and smart manufacturing continue to evolve, polysilicon-based transmitters will play an even more prominent role in intelligent process control systems.
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