What is a ceramic pressure sensor?

Ceramic pressure sensors are sensor diaphragms made of ceramic alumina (Al2O3). Ceramic is a material with high elasticity, corrosion resistance, wear resistance, impact, and vibration resistance. Ceramic has good thermal stability characteristics. High-temperature sintering process for the thick film. The working temperature range of the ceramic pressure sensor is as high as -40~125℃. The high elasticity and creep resistance of ceramics. The ceramic pressure sensor has good long-term stability. Besides, the corrosion resistance of ceramics. It has advantages in the fields of refrigeration, chemical industry, and environmental protection.

The Myth of Ceramic Pressure Sensor

The Basic Structure of Ceramic Pressure Sensor

The ceramic pressure sensor is mainly composed of a ceramic ring, a ceramic diaphragm and a ceramic cover plate.
The ceramic diaphragm acts as a sensitive elastic body. It is made of 95% AL2O3 porcelain. It is required to be flat, uniform and dense. Its thickness and effective radius depend on the design range.

The porcelain ring is shaped by high-temperature firing using a hot die-casting process. High-temperature glass slurry is used between the ceramic diaphragm and the ceramic ring. It is fired together by thick film printing and thermal firing technology. It forms a cup-shaped elastic body with a fixed peripheral edge. That is, a non-creep rigid structure should be formed in the fixed support part of the ceramic periphery.

On the upper surface of the ceramic diaphragm, which is the bottom of the porcelain cup. The circuit of the sensor is made with thick film technology. The circular groove at the lower part of the ceramic cover creates a certain gap between the cover and the diaphragm. The limit can prevent the diaphragm from rupturing due to excessive bending when it is overloaded. Form the anti-overload protection of the sensor.

Extended reading: Common Pressure Sensor Applications

Featured SI-338 Ceramic Pressure Sensor

SI-338 Ceramic Pressure Sensor

SI-338 Ceramic pressure sensor uses ceramic or diffused silicon core. All stainless steel package, small and beautiful appearance. Suitable for occasions with limited installation space. Wide range temperature compensation, high accuracy, small size, no adjustment, wide range coverage. Support OEM processing. Ceramic pressure transmitter is used in compressor, air conditioning and other pressure measurement.

Extended reading: What Is Flush Diaphragm Pressure Sensor?

Features of Ceramic Pressure Sensor

Ceramic is a recognized material with high elasticity, corrosion resistance, wear resistance, impact and vibration resistance. The thermal stability of ceramics and its thick film resistors can make its operating temperature range as high as -40 to 135°C. It also has high accuracy and high stability for measurement. Electrical insulation degree>2kV. Strong output signal. Good long-term stability.

Ceramic sensors with high characteristics and low prices will be the development direction of pressure sensors. In Europe and the United States, there is a trend to completely replace other types of sensors. In China, more and more users use ceramic sensors to replace diffused silicon pressure sensors.

  • Ceramic sensitive diaphragm with high overload capacity;
  • Zero point and full scale laser calibration;
  • Excellent anti-corrosion and anti-wear performance;
  • Anti-shock and anti-vibration;
  • High precision and high stability;
  • Wide operating temperature range;
  • Small size, easy to package;
  • Environmental friendly;

Extended reading: What is a pressure sensor?

Ceramic Pressure Sensor Working Principle

Ceramic Pressure Sensor Working Principle

The corrosion-resistant ceramic pressure sensor has no liquid transmission. The pressure directly acts on the front surface of the ceramic diaphragm, causing the diaphragm to produce a small deformation.

The thick film resistor is printed on the back of the ceramic diaphragm. Connected to form a Wheatstone bridge (closed bridge).

Due to the piezoresistive effect of the varistor, the bridge generates a highly linear voltage signal proportional to the pressure and proportional to the excitation voltage. The standard signal is calibrated to 2.0 / 3.0 / 3.3 mV/V according to the pressure range. Etc. Compatible with strain gauge sensors.

Calibration by laser. The sensor has high temperature stability and time stability. The sensor comes with a temperature compensation of 0~70℃. It can be in direct contact with most media.

Extended Reading: Up to 800°C High Temperature Pressure Sensor

Ceramic Pressure Sensor Types

The base material of ceramic pressure sensor is Al2O3 ceramic. According to the principle of realization, it can be divided into capacitive pressure sensor and piezoresistive pressure sensor.

The ceramic substrate and diaphragm are plated with metal and used as electrodes. The two ceramic parts are connected together by a glass seal. Maintain a controllable gap. So that the two metal electrodes form a capacitor.

If pressure is applied. Then the gap between the substrate and the diaphragm will be changed. Thereby changing the capacitance of the sensing element. The pressure-related signal output is formed by the subsequent processing circuit.

Because the edge of the ceramic diaphragm is fixed on the ceramic base. Peripheral support. When the force is applied, the middle deformation becomes larger, and the edge becomes smaller. The capacitance produces nonlinearity and reduces sensitivity.

In order to reduce temperature effects and edge effects. In the design, a circular single electrode is set on the ceramic diaphragm as the common electrode. Two electrodes are arranged on the ceramic cover plate to equalize the area. It forms a coaxial ring-shaped dual-capacitance sensor.

The center is the measurement capacitance Cp. The edge ring is the reference capacitor Cr. The outside of Cr is the fixed side. The subsequent signal conditioning circuit deals with the voltage difference between the two capacitors. The change of Cp and Cr is converted into DC voltage output by using square wave excitation signal. The magnitude of the applied pressure is measured by the difference signal of the two output voltages.

The dual-capacitor structure greatly reduces the nonlinear error of the sensor system. At the same time, when the ambient temperature changes, the two capacitors experience the same temperature change. The temperature effect of temperature on them is consistent. This offsets the measurement error caused by temperature changes. Realize the function of temperature self-compensation.

Extended reading: Featured Diaphragm Seal Pressure Transmitters

The piezoresistive pressure sensor is mainly composed of a ceramic ring, a ceramic diaphragm and a ceramic cover plate.

The ceramic diaphragm acts as a sensitive elastic body. On it, a thick film process technology is used to form a Wheatstone bridge as the sensor circuit. Due to the piezoresistive (deformation) effect of the resistor, a voltage signal is generated.

The thick film resistor is printed on the back of the ceramic diaphragm. Connected as a Wheatstone bridge (closed bridge).

When the pressure is zero. The bridge is in a balanced state, and the output voltage is zero.

When pressure is applied to the bridge. The deformation of the diaphragm causes the resistance of the four resistors of the bridge to change. The bridge is in an unbalanced state. Generate a highly linear voltage signal proportional to the pressure and proportional to the excitation voltage.

Due to the piezoresistive (deformation) effect of the resistor, a voltage signal is generated.

The standard signal is calibrated to 2.0 / 3.0 / 3.3 mV/V etc. according to the pressure range. Compatible with strain gauge sensors.

Calibration by laser. The sensor has high temperature stability and time stability. The sensor comes with a temperature compensation of 0~70℃. And can be in direct contact with most media.

Extended reading: Silicon Pressure Sensor

Frequently
Asked
Questions

There are many types of pressure sensors. Such as resistance strain gauge pressure sensors, semiconductor strain gauge pressure sensors, piezoresistive pressure sensors, inductive pressure sensors, capacitive pressure sensors, resonant pressure sensors, etc.

Extended reading: wireless pressure transmitter working principle

Currently, the most widely used pressure sensors include:

  • Diffused silicon piezoresistive pressure sensor,
  • Ceramic piezoresistive pressure sensor,
  • Sputtering thin film pressure sensor,
  • Capacitive pressure sensor,
  • Sapphire pressure sensor with high temperature resistance.
  • But the most widely used is the piezoresistive pressure sensor, which has a very low price, high accuracy and good linearity.

Extended Reading: Electronic Pressure Switch for Air Compressor

 Piezoresistive pressure sensor

The piezoresistive pressure sensor is constructed using the piezoresistive effect of single crystal silicon. A single crystal silicon wafer is used as an elastic element, and an integrated circuit process is used on the single crystal silicon membrane. A group of equivalent resistors are diffused in a specific direction of the single crystal silicon, and the resistors are connected into a bridge circuit. The single crystal silicon wafer is placed on Sensor cavity. When the pressure changes, the single crystal silicon produces strain, so that the strain resistance directly diffused thereon changes proportional to the measured pressure. Then the bridge circuit obtains the corresponding voltage output signal.

Extended reading: How do you calibrate a smart pressure transmitter?

Differential pressure sensor, as the name suggests, is a kind of sensor. But it is used to transmit pressure difference. So it is called differential pressure sensor.

Generally speaking, its function is mainly to measure the difference between two different pressures. And it is displayed by the sensor. The differential pressure sensor is often used to measure the pressure of the two end points before and after a certain part of a device Difference.

Extended reading: Miniature Pressure Switch

Extended Reading: Selection of pressure transmitter

Ceramic Pressure Sensor Cost

Ceramic Pressure Sensor has low cost. The price of the ceramic pressure transmitter that people often choose is basically between USD15~35. Save a lot of costs for customers.

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Sino-Inst offers Ceramic Pressure Sensors. A wide variety of Ceramic Pressure Sensors options are available to you. Such as free samples, paid samples. 

Sino-Inst is a globally recognized manufacturer of Ceramic Pressure Sensors, located in China. Sino-Inst sells through a mature distribution network that reaches all 30 countries worldwide. 

Pressure sensors products are most popular in Europe, Southeast Asia, and Mid East. You can ensure product safety by selecting from certified suppliers. With ISO9001, ISO14001 certification.

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