Pressure sensors are the most commonly used sensors and are widely used in various industrial automatic control environments, involving water conservancy and hydropower, railway transportation, intelligent buildings, production automation, aerospace, military industry, petrochemicals, oil wells, electric power, ships, machine tools, pipelines, etc. Many industries, the following is a brief introduction to the application of some commonly used pressure sensors.

An industrial automation system is usually divided into three parts: detection, control, and execution. As the control object of the automation system, industrial equipment must be compatible with the other two parts and provide a pressure sensor interface to make it a complete organic whole. Whether it is a stand-alone automation or a large-scale automation device, the control object should be protected to maximize its use.

Application of pressure sensors in weighing systems

In the commercial weighing system of industrial control technology, pressure sensing technology is being applied more and more.

In many pressure control processes, it is often necessary to collect pressure signals and convert them into electrical signals that can be automatically controlled.

Pressure control devices made with pressure sensors are generally called electronic weighing systems. Electronic weighing systems are becoming more and more important as online control tools for material flow in various industrial processes. Electronic weighing systems can not only be combined in the product manufacturing process to optimize production and improve product quality, but also collect and transmit data about material flow during the production process to the data processing center for online inventory control and financial settlement.

In the process automation control of weighing, the pressure sensor is required to not only sense the gravity signal, but also have reliable performance, good dynamic response, and good anti-interference performance; the signal provided by the pressure sensor can be directly displayed, recorded, printed, and stored by the detection system Or used for feedback regulation control.

Through integration technology, the pressure sensor and the measurement circuit are integrated, which greatly reduces the size of the entire device; in addition, the development of shielding technology will also ensure the anti-interference ability of the weighing pressure sensor, making the weighing process more automated. further improved.

Application of pressure sensors in petrochemical industry

Pressure sensors are one of the most used measuring devices in automatic control of the petrochemical industry. In large-scale chemical projects, almost all pressure sensor applications are included: differential pressure, absolute pressure, gauge pressure, high pressure, micro differential pressure, high temperature, low temperature, as well as remote flange pressure sensors of various materials and special processing. .

Almost the demand for pressure sensors in the petrochemical industry mainly focuses on three aspects: reliability, stability and high precision. Among them, reliability and many additional requirements, such as range ratio, bus type, etc., depend on the structural design, machining technology level and structural materials of the transmitter. The stability and high accuracy of the pressure transmitter are mainly guaranteed by the stability and measurement accuracy of the pressure sensor.

Corresponding to the measurement accuracy of the pressure transmitter is the measurement accuracy and response speed of the pressure sensor. Corresponding to the stability of the pressure transmitter are the temperature characteristics, static pressure characteristics and long-term stability of the pressure sensor. The demand for pressure sensors in the petrochemical industry is reflected in four aspects: measurement accuracy, fast response, temperature characteristics and static pressure characteristics, and long-term stability.

Micro pressure sensor is a new type of pressure sensor manufactured using semiconductor materials and MEMS technology. It has the advantages of high precision, high sensitivity, good dynamic characteristics, small size, corrosion resistance, and low cost. Pure single crystal silicon has low material fatigue, and micro-pressure sensors made of this material have good long-term stability. At the same time, the micro-pressure sensor is easy to integrate with the micro-temperature sensor to increase the temperature compensation accuracy and greatly improve the temperature characteristics and measurement accuracy of the sensor.

If two micro-pressure sensors are integrated, static pressure compensation can be achieved, thereby improving the static pressure characteristics of the pressure sensor. Today, micro-pressure sensors have many advantages that traditional pressure sensors do not have, and can well meet the needs of pressure sensors in the petrochemical industry.

Application of pressure sensors in water treatment

my country’s environmentally friendly water treatment industry has developed rapidly in recent years and has broad prospects for the future.

Water supply and wastewater treatment processes rely on the use of pressure sensors to provide important control and monitoring means for system protection and quality assurance.

The pressure sensor converts pressure (generally the pressure of liquid or gas) into an electrical signal output. This pressure electrical signal can also be used to measure the level of a static fluid, so it can be used to measure the liquid level. The sensitive component of the pressure sensor mainly consists of a silicon cup sensitive element, silicone oil, isolation diaphragm and air guide tube. The measured medium pressure P is transmitted to one side of the silicon cup element through the isolation diaphragm and silicone oil (see figure). The atmospheric reference pressure po Through the air guide tube, it acts on the other side of the silicon cup element. The silicon cup element is a cup-shaped single crystal silicon wafer with a very thin bottom. The diaphragm at the bottom of the cup produces elastic deformation with minimal displacement under the action of pressures P and Po. Monocrystalline silicon is an ideal elastomer, and its deformation is strictly proportional to the pressure, and its recovery performance is excellent.

The four bridge resistors formed by the semiconductor diffusion process on the silicon diaphragm are arranged in a square shape. When the silicon diaphragm is deformed under pressure, the two resistors on the diagonal are under compressive stress, while the other two resistors are under tensile stress. , due to the piezoresistive effect of diffused silicon, the resistance of the two opposite resistors increases, and the resistance of the other two resistors decreases. If voltage is applied to the two terminals A-A, there will be a voltage signal output between C-D that is proportional to the P-Po differential pressure.

Application of pressure sensors in smartphones

Pressure sensors are used on smartphones to measure atmospheric pressure, but what does measuring atmospheric pressure do for ordinary mobile phone users?

Altitude measurement
For those who like mountain climbing, they will be very concerned about their altitude. There are two commonly used methods for measuring altitude. One is through the GPS global positioning system, and the other is by measuring the atmospheric pressure and then calculating the altitude based on the air pressure value.

Due to the limitations of technology and other reasons, the GPS calculation altitude generally has an error of about ten meters, and if you are in the woods or under a cliff, sometimes you cannot even receive GPS satellite signals.

The range of options for air pressure methods will be wider, and the cost can be controlled at a relatively low level. In addition, the pressure sensor in mobile phones such as the Galaxy Nexus also includes a temperature sensor, which can capture the temperature and correct the result to increase the accuracy of the measurement result.

Therefore, adding a pressure sensor function to the original GPS of a smartphone can make three-dimensional positioning more accurate.

Assisted navigation
Nowadays, many drivers use mobile phones for navigation, but navigation on viaducts often makes mistakes. For example, when you are on a viaduct, the GPS cannot determine whether you are on the bridge or under the bridge, causing incorrect navigation.

And if a pressure sensor is added to the mobile phone, it will be different. Its accuracy can reach 1 meter, so that it can well assist GPS to measure the altitude, and the problem of wrong navigation will be solved.

Indoor Positioning
Since the GPS signal cannot be received well indoors, when the user enters a very thick building, the built-in sensor may lose the satellite signal, so the user’s geographical location cannot be recognized, and the vertical height cannot be sensed. And if the mobile phone is equipped with a pressure sensor and combined with accelerometer, gyroscope and other technologies, it can achieve accurate indoor positioning.

Applications of pressure sensors in the medical industry

With the development of the medical equipment market, higher requirements are put forward for the use of pressure sensors in the medical industry, such as accuracy, reliability, stability, volume, etc., all need to be improved. Pressure sensors have good applications in minimally invasive catheter ablation and body temperature sensor measurements.

Minimally invasive surgery can not only reduce trauma at the surgical site, but also greatly reduce the patient’s pain, and the recovery process is also very fast. To meet such requirements, in addition to the doctor’s surgical experience, it also requires various medical monitoring equipment. Many of the medical devices used for this procedure today are tiny, like various catheters and ablation devices. Catheters include thermodilution catheters, urethral catheters, esophageal catheters, central venous catheters, and intracranial pressure vessels. In addition to their conductive functions, the catheters provide an important guarantee for the smooth progress of pathological examinations and minimally invasive operations in patients with temperature or pressure sensors. , temperature and pressure parameters are critical parameters for successful operation.
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The ability to place the sensor close to the patient is critical for many applications such as dialysis where accurate measurements of dialysate and venous pressure are important. Pressure sensors must be able to accurately monitor the pressure of the dialysate and blood to ensure it remains within a set range.

This type of application requires that the sensor must be compact and able to withstand liquid media. In many cases, a sensor that is not compatible with liquid media requires additional mounting parts to protect it, adding size, cost and complexity to the product. Liquid media resistance is particularly important when monitoring patient respiration, where the sensor must be able to withstand the patient’s cough and exhaled moist air.
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In the automotive field, engine management is its main application, including manifold air pressure sensors in gasoline engines and common rail pressure sensors in diesel vehicles, especially in Europe. In order to improve combustion, some organizations are also working on pressure sensors that can work in the cylinder to better measure the exact ratio of various substances participating in the chemical reaction and feed the data back to the engine management system.

Due to the harsh working environment, automotive sensors are much more expensive than consumer sensors. In addition, automotive sensors require longer qualification times, and these sensors must work reliably for up to 15 years. Some sensors, such as brake or tire pressure sensors, are critical to vehicle safety.
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In the medical market, pressure sensors serve primarily as disposable, low-cost catheters for surgical use. But they are also used in expensive devices to sense pressure and differential flow in continuous positive airway pressure (CPAC) machines. These devices have great potential and may become implantable sensors after 2015. Implantable sensors don’t require batteries to operate and could be used for cardiac measurements and glaucoma monitoring.
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In the industrial field, the main applications of MEMS pressure sensors include heating, ventilation and air conditioning (HVAC), level measurement, and various industrial process and control applications. For example, in addition to precise altitude and pressure measurements, aircraft use sensors to monitor engines, flaps, and other components.

Over the past few years, the pressure sensor market has progressed rapidly, positively impacting the competitive landscape, introducing new players to the market and expanding the scope of existing players in the market.