The gas molecules and the sensitive film can exchange ions, thus a reduction reaction occurs, and the resistance of the sensitive film changes. The gas-sensitive thin film made of these metal oxides is an impedance device. It has been found that SnO2, ZnO, Fe2O3, Cr2O3, MgO, NiO2, and other materials have gas sensing effects. The principle of the resistive gas sensor is that gas molecules cause changes in the resistance of sensitive materials non-resistive gas sensors mainly include M()s diodes, junction diodes, and field-effect transistors (MOSFET), which uses the principle that the sensitive gases will change MOSFET turn-on voltage, and the principle structure is the same as ISFET (Ion-Sensitive Field Effect Transistor).

Semiconductor gas sensors can be divided into resistive and non-resistive (junction type, MOSFET type, capacitive type). Let's see several typical types of gas sensors: 1. There are many types of gases with different properties, so there are many types of gas sensors. Select appropriate materials and develop new materials to optimize the sensitivity of the gas sensor.

The four basic characteristics of the gas sensor are mainly determined by the choice of materials. When returning to normal operating conditions, the sensor drift and zero correction values should be as small as possible. When a large number of gas leaks, the probe should be able to withstand 10 to 20 times of the gas volume fraction. This characteristic is very important in the application of tracking multiple gases, because the cross-sensitivity will reduce the repeatability and reliability of the measurement, and an ideal gas sensor usually has high sensitivity and high selectivity.Ĭorrosion resistance refers to the ability of the sensor to be exposed to a high volume fraction of gas. This response is equivalent to the sensor response generated by a certain concentration of gas. It can be determined by measuring the sensor response caused by a certain concentration of interfering gas. Selectivity is also called cross-sensitivity. The sensitive technology of the gas sensors must have sufficient sensitivity for the detection of the threshold limit value(TLV) or lower explosive limit(LEL). Most gas sensors are designed using biochemistry, electrochemistry, physics, and optics. Sensitivity refers to the ratio of the output change to the measured input change of the gas sensor, which mainly depends on the technology used in the sensor structure. Ideally, the annual zero drift of a sensor is less than 10% under continuous operating conditions. Interval drift refers to the change in the output response of the sensor placed in the gas, which is represented by the decrease of the sensor output signal during the working time. Zero drift refers to the change in sensor output response during the entire working time when there is no gas. Stability refers to the stability of the basic response of the gas sensor during the entire working time, which depends on the zero drift and interval drift. Usually, gas sensors have the following properties: In the following, we'll mainly discuss the properties, typical types, and application fields of gas sensors. The probe uses the gas sensor to adjust the gas sample, which usually includes filtering out impurities and interfering gases, drying or refrigeration treatment, sample pump, and even chemical treatment of the sample, so that the chemical sensor can make faster measurements. Essentially, a gas sensor is a converter that converts a certain gas volume fraction into a corresponding electrical signal. Gas Sensor is the core of the gas detection system and is usually installed in the detection head.

Bluesense off gas sensors