What Are the Different Types of Gas Sensors? (Part 1)
GAS SENSORS, as we commonly refer to them, constitute a broad category that can be further subdivided into eight types based on their working principles. Users must understand the advantages and characteristics of each type to select correctly in specific application scenarios.
1. Electrochemical Gas Sensors
Working Principle: Gases undergo oxidation/reduction reactions with the sensor electrode surface, generating current or potential changes proportional to gas concentration.
Advantages:
1) Exceptionally high sensitivity, capable of detecting low-concentration gases at ppm or even ppb levels (e.g., toxic and hazardous gases);
2) High selectivity, enabling targeted detection of specific gases (e.g., CO, SO₂, NOₓ);
3) Low power consumption and compact size, suitable for portable devices and IoT modules.
Limitations:
1) Electrolytes are susceptible to temperature and humidity, resulting in poor long-term stability;
2) Limited lifespan (typically 1–3 years), requiring periodic calibration;
3) Poor tolerance to high concentrations of corrosive gases, prone to electrode damage.
Typical Applications: Industrial toxic gas detection, IAQ monitoring (formaldehyde), automotive exhaust emissions testing.
2. Catalytic Combustion Gas Sensor
Working Principle: Combustible gases combust upon the surface of the sensor’s catalytic element, releasing heat that alters the element’s resistance. Gas concentration is calculated based on this resistance value.
Advantages:
1) Rapid response to combustible gases such as methane and propane;
2) Strong resistance to interference, unaffected by non-combustible gases;
3) Simple structure and relatively low cost, suitable for industrial explosion-proof environments.
Limitations:
1) Detects only combustible gases;
2) Catalytic element susceptible to ‘poisoning’ and failure by sulphides and silicon compounds;
3) Operates at high temperatures (typically 300–500°C) with relatively high power consumption.
Typical Applications: Gas leak detectors, mine gas monitoring, industrial combustible gas surveillance.
3. Infrared Gas Sensors
Working Principle: Utilises the absorption characteristics of different gases towards specific infrared wavelengths, calculating gas concentration by detecting the degree of infrared light attenuation.
Advantages:
1) High selectivity, capable of precisely distinguishing between different gases (e.g., CO2 and CH4);
2) Excellent stability, no consumables, long service life (up to 5–10 years);
3) Resistant to gas ‘poisoning’, suitable for harsh environments.
Disadvantages:
1) Relatively high cost and complex structure;
2) High power consumption, unsuitable for portable devices;
3) Limited sensitivity for low-concentration gas detection (suitable for %-level concentrations).
Typical Applications: Industrial process gas analysis (CO2, CH4), automotive exhaust emissions testing, greenhouse gas monitoring.
4. Semiconductor Gas Sensor
Working Principle: Gas molecules adsorb onto the surface of semiconductor material, altering its electrical conductivity. Gas concentration is determined by measuring this conductivity change.
Advantages:
1) Extremely low cost and compact size, suitable for mass production;
2) Rapid response time, capable of detecting multiple gases (combustible and toxic gases);
3) Low power consumption, compatible with consumer electronics.
Disadvantages:
1) Poor selectivity, susceptible to interference from temperature, humidity and other gases;
2) Weak long-term stability with noticeable drift;
3) Sensitivity significantly affected by environment, requiring frequent recalibration.
Typical Applications: Domestic gas alarms, odour detection in air purifiers, portable gas detectors
Beyond these four types, gas sensors also employ photoionisation, laser spectroscopy, thermal conductivity, and solid electrolyte principles. We shall explore these further next time. Should you wish to enquire about gas sensor pricing or have any questions, please do not hesitate to contact us!