Introduction of Diffused Silicon Pressure Sensor

Jun 27,2023

Principle introduction

The diffused silicon pressure sensor uses the principle of piezoresistive effect, adopts integrated process technology to make strain resistance along the characteristic crystal direction on the single crystal silicon wafer through doping and diffusion, and forms a Wheatstone bridge. Utilizing the elastic mechanical properties of silicon materials, anisotropic micromachining is carried out on the same silicon material, and a diffused silicon sensor integrating force sensing and force-electric conversion detection is fabricated.

The pressure of the diffused silicon pressure sensor acts directly on the diaphragm of the sensor (stainless steel or ceramics), causing the diaphragm to produce a micro-displacement proportional to the medium pressure, and the resistance value of the sensor changes. The electronic circuit detects this change and converts A standard measurement signal corresponding to this pressure is output.

Features

1. Suitable for making small-range transmitters
The piezoresistive effect of the force sensitive resistor of the silicon chip has no dead zone in the low range near zero, and the range of the pressure sensor can be as small as several Kpa.

2. High output sensitivity
The sensitivity factor of silicon strain resistance is 50-100 times higher than that of metal strain gauge, so the sensitivity of the corresponding sensor is very high, and the general range output is about 100mv. Therefore, there is no special requirement for the interface circuit, and it is more convenient to use.

3. High precision
Since the sensing, sensitive conversion and detection of the sensor are realized by the same component, there is no intermediate conversion link, and the repeatability and hysteresis errors are small. Since the monocrystalline silicon itself has great rigidity and little deformation, good linearity is guaranteed.

4. Long life and stable performance
Due to the low deformation of the working unitary strain to the order of micro-strain, the maximum displacement of the elastic chip is on the order of sub-micron, so there is no wear, no fatigue, no aging, the service life is as long as 1×107 pressure cycles, stable performance and high reliability.

5. Strong corrosion resistance
Due to the excellent chemical anti-corrosion performance of silicon, even non-isolated diffused silicon pressure sensors have a considerable degree of ability to adapt to various media.

6. Small size and light weight
Since the chip adopts an integrated process and has no transmission parts, it is small in size and light in weight.

Applications

Diffused silicon pressure sensors are mainly used in industries such as process control systems, pressure calibration instruments, hydraulic systems, biomedical instruments, hydraulic systems and valves, liquid level measurement, refrigeration equipment, and HVAC control. It can be said that any industry with relatively high automation requirements, Diffused silicon pressure sensors may be used.

Diffused Silicon Pressure Sensor Applications

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