What Is Resistive Pressure Transducer?

Resistive pressure transducers are also called resistance pressure transducers. It is a commonly used pressure sensor. Pressure sensors are generally distinguished by principle: capacitive pressure transmitters, resistive pressure transducers, inductive pressure transmitters, semiconductor pressure transmitters, and pressure transmitters for high-frequency measurement. Among them, resistance pressure transmitters are commonly used.
Resistance strain pressure sensor is a kind of resistance pressure sensor. It measures the pressure value by the resistance change of the strain gauges bonded to the elastic element.

What Is Resistive Pressure Transducer

Resistive Pressure Transducer Working Principle

The functional principle of a resistive pressure transducer is very simple. A pressure sensor converts a mechanical pressure value into a proportional electrical signal. Pressure sensors usually consist of a body and a (thin) diaphragm.

The electrical components of resistance pressure transmitters that feel pressure are generally resistance strain gauges. Resistance strain gauges are sensitive devices that convert the pressure on the measured component into an electrical signal.

The diaphragm is the most important element for pressure measurement and is equipped with strain-sensitive and piezoresistive structures, so-called strain gauges. The diaphragm deflects under pressure.

The most widely used resistance strain gauges are metal resistance strain gauges and semiconductor strain gauges. There are two types of metal resistance strain gauges: filamentary strain gauges and metal foil strain gauges.

Usually, the strain gauge is tightly bonded to the matrix that generates mechanical strain through a special adhesive. When the stress of the matrix changes, the resistance strain gauge also deforms together, which changes the resistance value of the strain gauge. The voltage across the resistor changes.

For example, if a resistor is connected to a Wheatstone measurement bridge, an electrical signal can be measured and transmitted to the indicator.

Types of Pressure Transducers

Let’s talk about the classification of transmitters:

  1. According to the working principle of the sensor, it can be divided into resistance, capacitance, inductance, semiconductor, etc.;
  2. According to the classification of sensor chips, it can be divided into metal, ceramic, diffused silicon, sapphire, etc.;
  3. According to the measurement range, it can be divided into differential pressure, gauge pressure, absolute pressure, high static pressure and differential pressure, etc.;

Resistive pressure transducers are the most widely used transmitters and have the advantages of high cost performance and good linearity characteristics.

Types of Resistance Pressure Transducers

Resistive pressure transducers are generally divided into metal, ceramic, and diffused silicon according to pressure-sensitive components.

The difference between the three:

  1. The metal pressure transmitter has poor accuracy, but the temperature effect is small, and it is suitable for fields with a wide temperature range and low accuracy requirements.
  2. The accuracy of ceramic pressure sensors is better, but it is greatly affected by temperature. Another advantage of ceramics is impact resistance and corrosion resistance.
  3. Diffusion silicon pressure transmitter has high precision and large temperature drift, so it is generally necessary to perform temperature compensation before it can be used. And even after temperature compensation, pressures above 125°C cannot be measured. However, under normal temperature conditions, the sensitivity coefficient of diffused silicon is 5 times that of ceramics. Therefore, it is generally used in the field of high-precision measurement, but the accuracy is low in the micro-range.

Piezoresistive pressure sensor refers to a sensor made by using the piezoresistive effect of single crystal silicon material and integrated circuit technology.

After the single crystal silicon material is subjected to the force, the resistivity changes, and the electrical signal output proportional to the force change can be obtained through the measurement circuit.

It is also known as a diffused silicon piezoresistive pressure sensor. It is different from the adhesive strain gauge, which needs to indirectly feel the external force through the elastic sensitive element, but directly feels the measured pressure through the silicon diaphragm.

Capacitive pressure transducer (capacitive type pressure transducer) is a pressure sensor that uses capacitive sensing elements to convert the measured pressure into an electrical output that has a certain relationship with it. The characteristics are that the input energy is low, the dynamic response is high, the natural effect is small, and the environmental adaptability is good.

It generally uses a circular metal film or a metal-plated film as an electrode of the capacitor. When the film is deformed by pressure, the capacitance formed between the film and the fixed electrode changes. By measuring the circuit, the output voltage has a certain relationship with the voltage. electric signal.

Capacitive pressure sensors belong to the polar distance variable capacitive sensors, which can be divided into single capacitive pressure sensors and differential capacitive pressure sensors

The differential pressure transmitter is a transmitter that measures the pressure difference between the two ends of the transmitter, and outputs a standard signal (such as 4~20mA, 0~5V).

Differential pressure transmitters are different from general pressure transmitters in that they have 2 pressure interfaces. Differential pressure transmitters are generally divided into positive pressure ends and negative pressure ends.

In general, the pressure at the positive pressure end of the differential pressure transmitter should be greater than the pressure at the negative pressure section to measure.

The differential pressure transmitter is used to prevent the medium in the pipeline from directly entering the transmitter, and the pressure-sensitive diaphragm and the transmitter are connected by a capillary filled with fluid.

It is used to measure the liquid level, flow and pressure of liquid, gas or steam. Then convert it into 4~20mA DC signal output.

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Potentiometric pressure transducers are usually used for displacement, level and angle measurement.

The measured component is connected to the rotating shaft (or sliding arm) of the potentiometer through a certain mechanical transmission part. When the measured change changes, the sliding arm moves, and the resistance from the center of the potentiometer to the two fixed ends changes differentially.

The resistance change of the potentiometer can be converted into a voltage change output through a voltage divider circuit or a bridge circuit, and after A/D conversion, the measured physical quantity can be accurately measured. !

The hydraulic pressure transducer is mainly used in the pressure measurement of industrial equipment such as construction machinery, special equipment, compressors, injection molding machines, and servo equipment. It has good waterproof, small size and high cost performance. It is easy to install. The whole structure is made of stainless steel, which has good sealing, vibration resistance and stable and reliable performance.

Hydraulic pressure transducer is the extension and development of pressure transmitter technology. According to the principle that the pressure generated by different specific gravity liquids at different heights is linear. Realize the accurate measurement of the volume, liquid height and weight of water, oil and paste. Measure and transmit.

Strain Gauge Pressure Transducer Working Principle

The strain gauge pressure transducer works based on the principle of resistance strain effect.

There are two types of resistance strain gauges: metal strain gauges (wire or metal foil) and semiconductor strain gauges. The measured pressure strains the strain gauge.

When the strain gauge produces compressive strain, its resistance decreases. When the strain gauge produces tensile strain, its resistance increases.

The resistance value of the strain gauge changes, and then the corresponding millivolt-level potential output is obtained through the bridge circuit. The measured pressure is displayed by a millivoltmeter or other recording instruments. Thus, a strain gauge pressure gauge is formed.

Strain gauge structure: It consists of three parts: strain sensitive element, substrate and cover layer, and lead wire. Strain-sensitive elements are generally composed of metal wires and metal foils (high resistivity materials), which convert mechanical strain into changes in resistance. The substrate and cover layer serve to fix and protect sensitive components, transmit strain and electrically insulate.

Resistance strain pressure sensor structure: diaphragm type, cylinder type, combined type. Among them, the diaphragm type is suitable for low pressure measurement; the cylinder type is suitable for high pressure measurement.

The working mode of the resistance strain pressure sensor: the change of resistance is converted into the output of current or voltage signal through the unbalanced bridge.

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Frequently
Asked
Questions

Classification of working principle of pressure sensor

  1. Piezoresistive pressure sensor
  2. Ceramic pressure sensor
  3. Diffusion silicon pressure sensor:
  4. Sapphire pressure sensor:
  5. Piezoelectric pressure sensor:

Using a multimeter to test the pressure sensor can only perform simple tests, and the test results are only for reference.
There are roughly three tests that can be performed:

Bridge detection:
It mainly detects whether the circuit of the sensor is correct. Generally, it is a Wheatstone full-bridge circuit, which uses the ohm gear of the multimeter to measure the impedance between the input terminals and the impedance between the output terminals. These two impedances are the input and output of the pressure sensor. impedance. If the impedance is infinite, the bridge is disconnected. It means that there is a problem with the sensor or the definition of the pin is not correctly judged;

Detection of zero point:
Use the voltage range of the multimeter to detect the zero output of the sensor without applying pressure. This output is generally a mV level voltage. If it exceeds the technical specifications of the sensor, it means that the zero point deviation of the sensor is out of range;

Pressure detection:
The method of checking the order is: supply power to the sensor, blow the air guide hole of the pressure sensor with the mouth, and use the voltage range of the multimeter to detect the voltage change at the output end of the sensor. If the relative sensitivity of the pressure sensor is large, this amount of change will be significant. If there is no change at all, you will need to switch to an air pressure source to apply pressure.

These types of sensors are also called pressure transmitters. Because 4-20mA signals are least affected by electrical noise and resistance in the signal line, these sensors are best used when signals must be transmitted over long distances. These sensors are typically used in applications where the lead must be 1000 feet or more.

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Sino-Instrument is a globally recognized supplier and manufacturer of Resistive Pressure Transducers, located in China.

The top supplying country is China (Mainland), which supply 100% of Resistive Pressure Transducerrespectively.

Sino-Instrument sells through a mature distribution network that reaches all 50 states and 30 countries worldwide.

Resistive Pressure Transducer products are most popular in Domestic Market, Southeast Asia, and Mid East. 

You can ensure product safety by selecting from certified suppliers, with ISO9001, ISO14001 certification.

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