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This post was last edited by sdwfsgyykai on 2020-7-19 at 14:30. https://www.hnsxkj.cn/upload/202007/1594862853833512.jpg Point-type combustible gas detectors and electrochemical carbon monoxide gas sensors feature a closed structural design; their structure consists of components such as electrodes, filters, breathable membranes, electrolytes, electrode leads (pins), and casings. A carbon monoxide gas sensor, used in conjunction with an alarm, is the core sensing element of the alarm. It is based on the principle of fixed-potential electrolysis. When carbon monoxide diffuses into the gas sensor, a current is generated at its output, which is supplied to the sampling circuit in the alarm system, thereby converting chemical energy into electrical energy. When the gas concentration changes, the output current of the gas sensor also changes accordingly. It is amplified through the intermediate circuit of the alarm device, which in turn drives various actuating devices to carry out detection and alarm functions using sound, light, and electricity. These control devices together form an environmental detection or monitoring alarm system. When carbon monoxide gas diffuses through the pores in the sleeve via the permeable membrane to the surface of the working electrode, it is oxidized on that electrode under the catalytic action of the working electrode. Its chemical reaction equation is: CO + H2O → CO2 + 2H+ + 2e-. The H+ ions and electrons generated by the oxidation reaction at the working electrode are transferred through the electrolyte solution to the counter electrode located at a certain distance from the working electrode, where they undergo a reduction reaction with the oxygen in water. Its chemical reaction equation is: 1/2O2 + 2H+ + 2e- → H2O; therefore, a reversible redox reaction takes place inside the sensor. Its chemical reaction equation is: 2CO + 2O2 → 2CO2. This reversible redox reaction always takes place between the working electrode and the counter electrode, creating a potential difference between them. However, since reactions occur at both electrodes, the electrodes become polarized, which makes it difficult to maintain a constant potential between them, thereby limiting the range of detectable carbon monoxide concentrations. To maintain a constant potential between the electrodes, we added a reference electrode. In a three-electrode electrochemical gas sensor, the output reflects the potential difference between the reference electrode and the working electrode. Since the reference electrode does not participate in oxidation or reduction reactions, it can maintain a constant potential between the electrodes (i.e., a constant potential), at which point changes in potential are directly related to changes in carbon monoxide concentration. When a gas sensor generates an output current, its magnitude is proportional to the gas concentration. By measuring the output current of the sensor through electrode leads via an external circuit, the concentration of carbon monoxide can be detected, and it features a wide linear measurement range. In this way, the signal acquisition circuit along with the corresponding conversion and output circuits are externally connected to the gas sensor, thereby enabling the detection and monitoring of carbon monoxide gas.