Pressure sensor

Pressure sensor It refers to a sensor that converts pressure into electrical signal output. Pressure sensors are generally composed of elastic sensitive elements and displacement sensitive elements (or strain gauges). The function of the elastic sensitive element is to make the measured pressure act on a certain area and convert it into displacement or strain, which is then converted by the displacement sensitive element or strain gauge into an electrical signal that has a certain relationship with the pressure. Sometimes the functions of these two elements are integrated into one. Pressure sensors are widely used in various industrial automatic control environments, involving many industries such as water conservancy and hydropower, railway transportation, intelligent buildings, production automatic control, aerospace, military industry, petrochemicals, oil wells, electricity, ships, machine tools, pipelines, etc.

There are many types of mechanical sensors, but the commonly used pressure sensors include resistance strain gauge pressure sensors, semiconductor strain gauge pressure sensors, piezoresistive pressure sensors, inductive pressure sensors, capacitive pressure sensors, resonant pressure sensors and capacitive acceleration sensors, etc. The most widely used is the piezoresistive pressure sensor, which has extremely low price, high accuracy and good linearity.

The pressure sensor market in my country is mainly in the field of industrial automation control and the automotive field. In the field of industrial control, most of my country currently uses diffused silicon pressure sensors, strain gauge pressure sensors and sputtered thin film pressure sensors, and the most widely produced by domestic manufacturers is diffused silicon pressure sensors. In China, Xi'an is an important city that focuses on the development of pressure series sensors in my country's second five-year plan. Driven by the provincial capital Xi'an, Baoji City, Shaanxi Province, carried out technical transformation from the original Qinling Transistor Factory and cooperated with Honeywell Company of the United States to establish Mike Sensor Company, which pioneered the production of diffused silicon pressure sensors in my country. However, MEMS technology and front-end silicon wafer manufacturing technology are still controlled by foreign manufacturers.

The research on silicon capacitive pressure sensors in China can be said to have just started. Although some domestic units have developed silicon capacitive sensors, and their accuracy and static pressure characteristics are close to the average level of Fuji products, there is a big gap in long-term stability. At the same time, there is still a big gap in the development of high differential pressure and micro differential pressure specifications for domestic capacitive sensors. The accuracy of foreign piezoresistive sensors can reach 0.075%, while the accuracy of domestic piezoresistive sensors is only 0.1%. In terms of long-term stability performance, the gap between domestic sensors and imported sensors is more obvious. The long-term stability index of domestic products is 0.1%/year, which is at least 2 times higher than that of foreign products. In addition, the temperature characteristics of domestic products are poor. Compared with foreign products, the temperature drift is 50% to 100% larger than the typical value of foreign products. In addition, the specifications and varieties of domestic products are not complete, and there are no mature products in terms of micro differential pressure, high differential pressure and high static pressure specifications, which cannot meet the special requirements of certain processes.

The key to the localization of pressure sensors is how to improve the long-term stability of the sensors. The long-term stability of the sensors is closely related to the material selection, structural design, and processing technology of the sensors. my country is still at a relatively backward stage in MEMS processing technology, and improving the process level is undoubtedly a long-term strategy to improve sensor performance.

At present, relevant domestic universities and research institutes have conducted a lot of research on piezoresistive and capacitive MEMS sensors, and have achieved some results in both theory and process. As far as the current process level is concerned, if some form of compensation or online self-calibration method can be achieved, it is possible to improve the long-term stability of the sensor in the short term, so that domestic sensors can meet the needs of the petrochemical industry in terms of stability indicators.

The main domestic pressure sensor manufacturers include: Shaanxi Qinming Electronics Co., Ltd. (pressure sensors and transmitters), Kunshan Shuangqiao Sensor Measurement and Control Technology Co., Ltd. (piezoresistive pressure sensors), Beijing Zhongke Meanwell Technology Co., Ltd., Beijing Ruiliwell Technology Development Co., Ltd., Shanghai Lingsheng Electronic Instrument Co., Ltd., Beijing Xinnuojin Sensing Technology Co., Ltd., Nanjing Gaohua Technology Co., Ltd., Shenzhen Weina Xinke Optoelectronics Co., Ltd., Beijing Jade Bird Yuanxin Microsystem Technology Co., Ltd., Shanghai Zhaohui Pressure Instrument Co., Ltd., Shenzhen Kepuri Sensing Instrument Co., Ltd., and Mike Sensor Co., Ltd.