Understanding the Strain Gauge Pressure Sensor Technology
- Jeff Matthrews
- 6 days ago
- 6 min read
Introduction to Pressure Sensors
Pressure sensors are devices that measure pressure, defined as force exerted over an area - a crucial component in various applications, including HVAC systems and industrial automation.
The pressure sensor technology has evolved to include microfused pressure sensors, which offer high accuracy and reliability in measuring pressure.
Pressure measurement is critical in predicting maintenance needs and ensuring equipment performance, making pressure sensors essential devices in many industries.
Custom pressure sensors can be designed to meet specific application needs, providing accurate pressure measurement in a wide range of environments.
Pressure Measurement Technologies
There are various types of pressure measurement technologies, including silicon strain gauge, capacitive, and piezoelectric sensors, each with its advantages and disadvantages.
Microfused pressure sensor technology combines the benefits of silicon strain gauge and stainless steel diaphragm, providing a wide operating temperature range and high accuracy.
Pressure transducers and pressure transmitters convert the measured pressure through a strain gauge into an electrical signal for control and monitoring purposes.
The choice of pressure measurement technology depends on the specific application, including the type of fluid, pressure range, and environmental conditions.
A strain gauge is basically a tiny variable resistor whose resistance changes when it bends or stretches—but the change is so small that we need the Wheatstone bridge to detect it. In this circuit, three precision resistors and one strain gauge form a balanced setup where the output voltage is normally zero. When the strain gauge deforms, its resistance shifts, unbalancing the bridge and creating a measurable voltage difference. That voltage directly corresponds to how much strain is applied. And that’s the simple idea behind how Wheatstone bridge circuits let us measure strain in pressure sensors
Types of Pressure Sensors
Pressure sensors include absolute, gauge, and differential types, each designed to measure specific pressure types with distinct principles and applications.
Absolute pressure sensors measure pressure relative to a perfect vacuum (zero reference), making them ideal for accurate atmospheric or vacuum pressure measurements. The sensor achieves this by comparing the target pressure to a sealed, internal reference cavity that has been evacuated to an absolute vacuum (see diagram below). This concept is similar to measuring temperature in Kelvin, where 0 K represents the lowest physically possible temperature.
Using a perfect vacuum as the reference ensures that all measured pressures are greater than this absolute minimum. This is critical for accuracy: according to Boyle’s Law, the pressure of a gas is inversely proportional to its volume at a constant temperature. If the reference were anything other than a true vacuum, its pressure would change with temperature, causing the sensor’s output to drift. A perfect vacuum, however, eliminates this dependency and provides a stable, unchanging reference point.
Gauge pressure sensors measure pressure relative to the local atmospheric pressure, rather than relative to a vacuum. They are used when the absolute value of pressure is less important than understanding how much a system’s pressure differs from the surrounding air—such as in medical suction pumps, where a safe and finely controlled vacuum must be maintained regardless of altitude or weather-related changes in atmospheric pressure.
A gauge pressure sensor typically consists of a pressure port connected to the system being measured and a vent open to ambient air, ensuring the sensor always references the current atmospheric pressure. Internally, most modern gauge sensors use a thin membrane fitted with piezoresistive elements whose resistance changes when the membrane flexes under pressure. These elements are arranged in a Wheatstone bridge configuration and powered by a constant current source.
Differential pressure sensors are used when the absolute pressure of a gas or liquid is not required, and only the pressure difference between two points in a system needs to be measured. They provide a comparative reading—for example, across a valve in a pipeline, where equal pressures indicate an open valve, while a difference may suggest a restriction or blockage. These sensors typically feature two ports, each connected to a point in the system, and the measurement they provide is fully independent of atmospheric pressure.
Most differential sensors use a single diaphragm with the two pressures applied to opposite sides; the diaphragm’s deflection, positive or negative, directly corresponds to the pressure difference. In more advanced industrial designs, the measurement may come from two absolute pressure sensors whose outputs are electronically processed to compute the differential value—useful when the media or environmental conditions differ on each side. For simplicity, manufacturers also offer fully integrated differential pressure sensors that include amplification and compensation circuitry, enabling direct, ready-to-use digital or analogue outputs.
Pressure sensors can be classified based on their output signal (analog or digital) and sensitivity to temperature and vibration.
Materials such as stainless steel and silicon provide durability to withstand harsh environments and ensure long-term reliability.
Applications include pneumatic systems, hydraulic systems, and quality control systems.
Choosing the Right Pressure Sensor
Selection depends on factors like fluid type, pressure range, environmental conditions, and required accuracy.
The sensor's output signal must be compatible with the control system and able to withstand expected temperature and vibration levels.
Consulting with a product specialist is recommended for selecting the appropriate sensor.
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Frequently Asked Questions (FAQ) About Micro Fused Strain Gauge Pressure Sensors
Q1: What are the main advantages of micro fused pressure sensors?
These sensors offer high accuracy, durability, and reliability. They can withstand harsh environments including exposure to corrosive media, high temperatures, shock, and vibration. Their robust structure reduces the risk of leakage and ensures long-term stable performance.
Q2: In which industries are micro fused strain gauge pressure sensors commonly used?
They are widely used in industrial automation, HVAC systems, automotive applications, chemical processing, and hydraulic and pneumatic systems where precise and reliable pressure measurement is critical.
Q3: How do micro fused sensors handle electromagnetic interference?
Due to their design and materials, micro fused sensors exhibit strong resistance to electromagnetic interference, ensuring accurate pressure measurement without signal distortion.
Q4: What is the difference between a pressure sensor, transducer, and transmitter?
A pressure sensor detects pressure and converts it into an electrical signal. A transducer converts this signal into a usable output voltage or current, while a transmitter further amplifies and transmits this signal over longer distances, often as a standardized current signal like 4-20mA.
Q5: Can micro fused strain gauge pressure sensors measure differential pressure?
Yes, specialized differential pressure sensors measure the difference between two pressure points, which is essential for monitoring systems such as pumps and compressors.
Q6: What are the three different types of pressure sensors: differential, gauge, and absolute?\
Differential pressure sensors measure the difference between two pressure points and are commonly used in applications like flow measurement and filter monitoring.\
Gauge pressure sensors measure pressure relative to ambient atmospheric pressure, often used in hydraulic and pneumatic systems.\
Absolute pressure sensors measure pressure relative to a perfect vacuum, making them ideal for applications requiring precise atmospheric or vacuum pressure readings.
Q7: How are these sensors calibrated?
Micro fused strain gauge pressure sensors are typically calibrated using precision tools and standards to ensure their output signal is proportional to the pressure experienced, maintaining measurement accuracy across the pressure range.
Q8: What are typical output signals from these sensors?
They usually provide analog output signals, such as voltage or current (e.g., 4-20mA), which can be easily integrated into control and monitoring systems via cables and connectors.
Q9: How do these sensors perform in corrosive environments?
With stainless steel and other corrosion-resistant materials, micro fused sensors are designed to withstand exposure to corrosive media including acids, alkalis, and salt spray, ensuring safety and longevity in challenging environments.
These sensors consistently offer reliable performance and precise measurements, making them essential for critical applications across multiple sectors.
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