Hydrogen pressure sensor: At present, among the sensors used for hydrogen detection, the semiconductor hydrogen pressure sensor is a resistance sensor. Due to their high sensitivity, ease of miniaturization and ease of array, they can be integrated into miniature and low-power detection probes. They have been widely used in portable, online detection and other applications. The working temperature of semiconductor sensors is generally above 250°C to ensure measurement accuracy and response time, but in a specific environment, too high working temperature will bring safety hazards.

By coating and doping noble metals, the sensitivity of the gas sensing material SnO2 to hydrogen at low temperature is effectively improved. The working temperature characteristics of the new sensor under special working conditions (low humidity and low oxygen) are studied.

1. Semiconductor Hydrogen Pressure Sensor

1. Working mechanism

Semiconductor gas sensors use changes in conductivity and other physical properties when the gas to be tested is in contact with the surface of a semiconductor (mainly a metal oxide) to detect gas. When the semiconductor gas-sensitive device is heated to a stable state, physical and chemical adsorption and desorption will occur on the surface of the gas-sensitive material: the gas-sensitive material adsorbs oxygen molecules and obtains electrons from the semiconductor surface, forming acceptor surface energy levels such as O-1 and O-2, and the resistance value increases; When hydrogen is in contact with the gas-sensitive material, the electrons captured by oxygen atoms return to the semiconductor, and the resistance decreases.

2. Gas sensitive materials

Scholars at home and abroad have done a lot of research on the working temperature and gas selectivity of gas-sensitive materials. At present, the material systems based on SnO2, WO3 and ZnO show good gas-sensing properties.

3. Working temperature

The gas-sensitive materials exhibit different adsorption capacities at different temperatures. Taking SnO2 and ZnO as an example, its adsorption capacity. The performance of the hydrogen pressure sensor is closely related to its operating temperature. At a suitable operating temperature, the response time and accuracy of the gas-sensitive material will be improved. However, in order to ensure the safety during use, the working temperature of the sensor should not be too high, and too low temperature will affect the test accuracy of the sensor. Therefore, it is necessary to study the working temperature characteristics of hydrogen pressure sensor in detail.

Effect of Working Temperature on Response Accuracy of 2. Gas Sensing Material

1. Selection of hydrogen pressure sensor

At present, SnO2, WO3 and ZnO are very commonly used gas-sensitive materials for semiconductor hydrogen pressure sensors. However, SnO2, WO3 and ZnO have little difference in gas sensitivity to hydrogen, and the hydrogen sensitivity is relatively poor. After adding precious metals, SnO2 has good sensitivity and selectivity to hydrogen, and the operating temperature response range is also low. Therefore, the hydrogen pressure sensor doped with noble metal SnO2 is selected as the gas sensitive material as the research object.

2. Establishment of experimental system

In order to simulate the actual situation, the experimental design of the gas sensor environmental evaluation device is carried out. Since the sensor is stored in a sealed container or packaging container for a long time, the sealing performance of the storage container is very high. At the same time, in order to meet the humidity requirements, replace the sealed container or packaging container with dry nitrogen, so that the pressure is maintained at atmospheric pressure, the relative humidity is less than 10%, and the oxygen content is less than 1%. In order to better simulate the various functional requirements of storage experiments, the designed sealed container should be able to achieve the functions of inflation and replacement of pneumatic energy, as well as sensor switching and sealing.

Jiangmen Hengmin Intelligent Control Instrument Co., Ltd. is a pressure transmitter manufacturer, mainly engaged in oil pressure sensors, wall-mounted boiler water pressure sensors, urea pump pressure sensors, hydrogen pressure sensors, pressure calibrators, automobile pressure sensors, water pump pressure sensors, water pressure Sensors, intelligent pressure controllers, high pressure sensors and other products. Our company found in the research industry production activities that with the increasing popularity of the Internet of Things and intelligent manufacturing concepts, the demand for pressure sensors in my country has grown rapidly in recent years. In response to the needs of the era of intelligent manufacturing, our company has developed high-precision testing instruments and special production system equipment for pressure sensor manufacturers to help sensor manufacturers greatly reduce the labor intensity of testing, reduce the number of workers, improve product quality, improve production efficiency and reduce production costs.