Electrochemical sensors for use in gas detection instruments
A gas detector is an instrument tool for gas leakage concentration detection, mainly referring to portable/handheld gas detectors. Gas sensors are mainly used to detect the types of gases present in the environment. Gas sensors are sensors used to detect the composition and content of gases. It is generally believed that the definition of gas sensor is based on the detection target. That is to say, any sensor used to detect gas composition and concentration is called a gas sensor, regardless of whether it uses physical methods or chemical methods. For example, a sensor that detects gas flow is not considered a gas sensor, but a thermal conductivity gas analyzer is an important gas sensor, although they sometimes use roughly the same detection principle.
electrochemical sensor
A considerable part of its flammable, toxic and harmful gases are electrochemically active and can be electrochemically oxidized or reduced. Using these reactions, gas components can be distinguished and gas concentrations can be detected.
Electrochemical gas sensors are divided into many subcategories:
(1) Primary cell gas sensor (also known as: Gavoni cell gas sensor, also known as fuel cell gas sensor, also known as spontaneous battery gas sensor), their principle is the same as the dry battery we use, but, The battery's carbon-manganese electrode was replaced by a gas electrode. Taking an oxygen sensor as an example, oxygen is reduced at the cathode and electrons flow through the ammeter to the anode, where the lead metal is oxidized. The size of the current is directly related to the concentration of oxygen. This sensor can effectively detect oxygen, sulfur dioxide, chlorine, etc.
(2) Constant potential electrolytic cell type gas sensor. This type of sensor is very effective for detecting reducing gases. Its principle is different from that of the primary cell type sensor. Its electrochemical reaction occurs under the force of current. It is a A truly coulometric sensor. This kind of sensor has been successfully used in the detection of carbon monoxide, hydrogen sulfide, hydrogen, ammonia, hydrazine, and other gases. It is the mainstream sensor for the detection of toxic and harmful gases.
(3) Concentration battery-type gas sensor. The electrochemically active gas will spontaneously form a concentration electromotive force on both sides of the electrochemical cell. The size of the electromotive force is related to the concentration of the gas. A successful example of this kind of sensor is the automotive one. Oxygen sensor, solid electrolyte carbon dioxide sensor.
(4) Limiting current type gas sensor. There is a sensor that measures oxygen concentration. It uses the principle that the limiting current in the electrochemical cell is related to the carrier concentration to prepare an oxygen (gas) concentration sensor. It is used for oxygen detection in automobiles and in molten steel. Oxygen concentration detection.
