Technology popularization | How pressure sensors work


In the field of industrial automation, pressure is one of the crucial parameters, as it directly impacts process safety, efficiency, and product quality. In various industrial environments such as oil refining and chemical plants, maintaining appropriate pressure is key to preventing accidents and ensuring personnel safety. Pressure data is used not only to monitor and regulate industrial processes like chemical reactions, thermal energy conversion, and fluid dynamics, ensuring their optimal operation, but also to achieve energy savings, improve production efficiency, and optimize product quality through precise pressure control. Additionally, pressure control is extremely important in the food, beverage, and pharmaceutical industries, ensuring product quality and compliance with health standards, such as ensuring containers are leak-proof and products are well-sealed during filling operations. Accurate pressure control can significantly reduce energy consumption and raw material waste, thus reducing production costs.

Pressure Sensor

First, let's understand the working principle of pressure sensors.

Working Principle of Pressure Sensors

There are various working principles of pressure sensors, and here are some main types:

  • Piezoresistive Sensors

Piezoresistive Sensor

These work based on the piezoresistive effect, where the resistance of a material (usually semiconductor or metal) changes when subjected to pressure. This resistance change is converted into a voltage or current change, generating an electrical signal proportional to the applied pressure. Due to their high accuracy and stability, they are commonly used for monitoring and controlling pressure in industrial processes.

  • Capacitive Sensors

Capacitive Sensor

Capacitive sensors measure pressure by utilizing changes in capacitance. They typically consist of two metal plates, one of which is movable. When pressure is applied to the movable plate, the distance between the plates changes, resulting in a change in capacitance. This capacitance change is then converted into an electrical signal. Due to their high sensitivity and small size, they are suitable for applications requiring miniaturized sensors, such as medical devices (blood pressure monitoring) and microrobots.

  • Piezoelectric Sensors

Piezoelectric Sensor

These operate based on the piezoelectric effect, where certain materials (such as quartz or certain ceramics) generate an electric charge when subjected to mechanical stress. The charge produced is proportional to the applied force. This charge can be measured and converted into an electrical signal, indicating the magnitude of pressure. Piezoelectric sensors are particularly suited for measuring dynamic or rapidly changing pressures, such as in explosion testing and automotive crash testing.

SENTINEL Pressure Sensors

SENTINEL's pressure sensors are widely used in metallurgy, machine tools, and the food and beverage industry. Over the past sixteen years, SENTINEL's pressure sensors have received unanimous praise from customers for their extremely low failure rates and comprehensive after-sales service.

Currently, our company offers two types of piezoresistive pressure sensors: one without a display and another with an integrated digital display featuring IO-Link functionality.

S300 Series Pressure Transmitters

S300 Series Pressure Transmitter

This series of pressure transmitters is compact and detects pressure ranges from -1 to 600 bar, with optional 4-20mA or 0-10V outputs.

SEH Series Pressure Sensors

SEH Series Pressure Sensor

This series of pressure sensors integrates IO-Link functionality, showcasing several innovative features:

  1. Measurement range of -1 to 600 bar, suitable for various industrial applications.
  2. Large digital display visible within a 3-meter range, supporting mirrored display to enhance data reading convenience and accuracy.
  3. New panel design with integrated injection molding, resistant to high-pressure water jets.
  4. 304/316 stainless steel housing that can rotate 300 degrees for easy installation.

Additionally, this series of pressure sensors can switch between various output modes:

OUT1 Output Modes

OUT1: Can be set to switch output or IO-Link output, meaning it can function as an IO-Link slave device connected to an IO-Link master or as a standard pressure sensor outputting a switch signal. The switch signal can be further configured, such as normally open/normally closed, PNP/NPN/push-pull output, hysteresis mode/window mode.

Hysteresis mode ensures a stable switch state unaffected by pressure fluctuations, while window mode can determine if the pressure is within a specific range and trigger an output switch, generating an alarm signal accordingly.

OUT2 Output Modes

OUT2: Can be set to analog (4-20mA) or switch output, with switch output configurations similar to OUT1. When choosing analog output, users can set the analog start and end points to determine the corresponding relationship.

Analog Output Modes

IO-Link Predictive Maintenance

Tianjin SENTINEL Electronics Co., Ltd. leads the industry by introducing pressure sensors integrated with IO-Link functionality. These sensors utilize IO-Link technology to convert the millivolt signal of pressure directly into digital signals, achieving high-precision data transmission and strong anti-interference capabilities. Additionally, some sensor data (internal temperature, operating time, etc.) is "packaged" and sent to the PLC, providing information for predictive maintenance.

For example, a pressure sensor in a hydraulic station might indicate "high internal temperature" while the pressure signal output is normal. This situation alerts the user to take measures to prevent potential equipment failure.

With self-diagnostic capabilities, these sensors simplify equipment maintenance processes. By diagnosing and reporting potential issues in a timely manner, they significantly reduce equipment downtime and maintenance costs, enhancing production efficiency.

IO-Link Functionality

Case Study: Hydraulic Systems in Machine Tools

Hydraulic Systems in Machine Tools

A precision machine tool manufacturer extensively uses our SEH series pressure sensors in their equipment's hydraulic systems. These sensors monitor the pressure of hydraulic oil, ensuring stable performance during high-load and high-speed operations. With IO-Link functionality, customers can monitor the pressure status of their equipment as well as the status of the sensors. This significantly improves system reliability and maintenance efficiency. Additionally, the multifunctional output settings allow these sensors to adapt flexibly to different control needs, simplifying system design and subsequent maintenance.


We are committed to enhancing product performance and service quality through technological innovation. In the future, we will continue to explore new technologies and expand our product line to meet the growing market demand. We believe that continuous technological innovation and quality service are essential for creating greater value for our customers.

Customer Support and Service

For more information on general-purpose flow, please contact our sales staff or call the company at 022-83726972. You can also visit SENTINEL's official website at The website offers comprehensive product information, selection manuals, CAD and Eplan files, and configuration files and tutorials to ensure users can easily obtain the information they need.

We have a professional technical team ready to provide customized customer support and efficient after-sales service, ensuring that every user’s benefits are maximized.