Carbon Monoxide Electrochemical Sensors: A Technological Tool for Protecting Life

Introduction

Gas sensing technology is becoming increasingly important as technology continues to advance and society continues to grow. In this field, DFRobot's latest carbon monoxide gas sensor is certainly a compelling innovation. In this article, I would like to introduce you to the working principle of the carbon monoxide electrochemical sensor while demonstrating a vivid device. Let's unravel the mystery of electrochemical carbon monoxide sensors as we delve into this fascinating topic.

About Product

This Gravity: Carbon Monoxide Sensor is one of the latest electrochemical gas sensors launched by DFRobot. They have the features of accurate measurement, high sensitivity and low power consumption, as well as excellent stability and anti-interference. It has three output modes: I2C, UART and analog. This sensor works at 3.3V~5V, so it is compatible with various mainstream controllers such as Arduino ESP32 and Raspberry Pi, etc. 

Of course, like the previous oxygen sensors, all supported gas probes are factory calibrated.The sensor has a built-in threshold mode, which can be a gas alarm by setting the threshold.

Working Principle

The electrochemical carbon monoxide sensor consists of three electrodes: working electrode (WE), counter electrode (CE), and reference electrode (RE).

When carbon monoxide comes into contact with the working electrode, an oxidation reaction occurs, producing carbon dioxide and hydrogen ions, and generating electrons. 

The generated hydrogen ions and electrons then move to the counter electrode and react with oxygen to produce water. The overall reaction is that carbon monoxide is oxidized to carbon dioxide, the electron flow forms an external current.

The reaction equation shows that the magnitude of the current is directly proportional to the concentration of carbon monoxide. Since the reactions occurring at both electrodes will polarize the electrodes, which makes it difficult to maintain a constant potential between them.

So, this carbon monoxide sensor is fitted with a reference electrode. For a three-electrode electrochemical gas sensor, its output reflects the change in potential between the reference electrode and the working electrode.

The reference electrode can provide a stable electrochemical potential in the electrolyte because it does not participate in the electrochemical reaction. Therefore, the potential change is directly related to the concentration change of the measured gas.

Let's make a project to see how it is applied.

Candle experiment

1. Connect the sensor’s alarm(ALA) pin to a digital input pin of Arduino.

2. Light a candle, put the candle and gas sensors into a clear container.

3. We can read the concentration of carbon monoxide and hydrogen sulfide on the LCD screen. When the concentration of carbon monoxide exceeds the threshold, the LED blinks to give an alarm.

4. The data show that the hydrogen sulfide sensor and carbon monoxide sensor are especially sensitive to specific gases, and electrochemical gas sensors have a certain anti-interference ability.

Conclusion

This article explores the principles of electrochemical carbon monoxide sensors and their applications in real-world projects. A demo project illustrates how these sensors detect carbon monoxide concentration, triggering alarms when thresholds are surpassed. We also highlight the sensors' sensitivity to hydrogen sulfide, immunity to interference, making them versatile in various environments. 

As technology advances, gas sensors will play a crucial role in monitoring and enhancing environmental quality and safety. We hope this information enhances your understanding of electrochemical carbon monoxide sensors, inspiring further exploration. If you have any questions or suggestions, please feel free to leave a comment and let me know!