Development of Gas Detector Sensors

    Gas alarms play a relatively important role in production safety. In China, alarms have been developed from scratch in manufacturing enterprises, and now they are more and more widely used. Sensors, the core components of gas detectors, play an increasingly important role. Sensors are divided into semiconductor, catalytic combustion, and electrochemical sensors according to gas-sensitive materials and gas-sensitive properties. Sensors are divided into infrared and photoionization sensors according to spectral analysis and measurement. A new generation of sensors, graphene sensors, are about to be born, which have many advantages that traditional sensors cannot match. Semiconductor sensors began to be used in 1962, mainly for measuring combustible gases. They were used relatively early and use the current or voltage of gas-sensitive elements to change with the gas content to measure the gas concentration. This type of sensor has poor selectivity and is rarely used now. Most of the detection of combustible gases now uses catalytic combustion. Platinum wires coated with catalyst materials cause resistance changes when combustible gases burn at high temperatures, and current changes to measure gas concentrations.

   The characteristic is stability. Electrochemical sensors are mainly used to measure toxic gases, including oxygen. The gas to be measured undergoes an oxidation-reduction reaction through a platinum wire catalyst film, and then the current generated during gas electrolysis is measured through the circuit acquisition system in the instrument, and then the gas concentration is calculated. It has high sensitivity, good selectivity, simple structure, and can be used at room temperature. Infrared sensors measure the concentration of combustible gases by measuring the changes in the spectrum of the gas before and after infrared irradiation. This type of sensor has good selectivity and high sensitivity. The price is relatively high. Photoion sensors use the gas molecules to ionize into positive and negative ions after ultraviolet irradiation, and the ultraviolet spectrum changes to measure the gas concentration. It mainly measures volatile organic compounds. It has high sensitivity, good selectivity, and a relatively high price. The new generation of sensors, graphene sensors, have begun to emerge due to their unique advantages. It measures the gas concentration by changing the resistance through the adsorption of gas molecules on graphene.