What Is a Gas Sensor?

Gas sensor is a device that detects and measures gases present in the air or environment. For example, it is commonly used in homes so that even if a hazardous gas (such as carbon monoxide) leaks, the sensor can trigger an alarm and prevent harm to individuals.

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This type of gas sensor operates through electrodes inside it:

• The gas reaches a metal surface called the detection electrode, where a chemical oxidation or reduction reaction (i.e. chemical change) occurs.
• The current (electrical flow) produced by this reaction is measured.
• The strength of the current is directly proportional to the amount of gas in the environment: the more gas present, the stronger the current.

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These sensors do not require external voltage (electrical power):

• For example, oxygen gas reacts between an anode and a cathode, producing electrons (electricity).
• The generated electricity powers the sensor.
• The amount of electricity produced also indicates the concentration of the gas.

In electrochemical sensors, a reference electrode is present alongside the detection electrode:

• The reference electrode ensures the sensor operates stably and helps produce accurate measurements.
• This component provides a fixed (stable) voltage to the detection electrode and prevents measurement drift during operation.

• They alert us when harmful gases are present in the air.
• We can detect dangers early, thereby ensuring our safety.
• They help us understand how the technology functions.

Term - Description

Detection electrode The metal surface where the gas reacts; the chemical reaction occurs here.

Anode / Cathode The two electrodes through which electrons flow during the chemical reaction.

Oxidation / Reduction In chemistry, the loss of electrons by a substance (oxidation) or the gain of electrons (reduction).

Reference electrode The electrode that provides a stable voltage to maintain sensor balance.

Ammeteric sensor A sensor that determines gas concentration by measuring electrical current.

Micro fuel cell A sensor type that generates electricity through gas reaction (no external voltage required).