What Are electrochemical sensors?
Electrochemical sensors (or cells) are widely used for detecting toxic gases in ambient air. They operate by converting a chemical reaction into an electrical signal, providing accurate and selective measurements of gas concentrations.
How does the technology work?
- Basic Principle: The sensor consists of three electrodes (working, counter, and reference) immersed in an electrolyte.
- Gas Diffusion: Target gas molecules diffuse through a permeable membrane into the sensor.
- Electrochemical Reaction: At the working electrode, the gas undergoes oxidation or reduction, generating an electrical current.
- Signal Output: The current produced is proportional to the gas concentration, allowing precise measurement.
Typical uses
Electrochemical gas sensors are commonly used for:
- Industrial Safety: Detecting toxic gases like carbon monoxide (CO), hydrogen sulfide (H₂S), sulphur dioxide (SO2), chlorine (Cl₂), and ammonia (NH₃).
- Environmental Monitoring: Measuring air pollutants in urban and industrial areas.
- Confined Space Monitoring: Ensuring safe conditions for workers in tanks, tunnels, and vessels where Oxygen (O2) levels may get depleted.
- Portable Gas Detectors: Integrated into handheld multi-gas monitors for personal protection.
Advantages of electrochemical gas sensors
- High Selectivity: Designed for specific gases, reducing cross-sensitivity.
- Low Power Consumption: Ideal for portable and battery-operated devices.
- Low Cost: Allowing for cost effective multi-point measurements
- Compact Size: Easily integrated into small instruments.
- Good Accuracy: Reliable measurements at low concentrations.
Disadvantages of electrochemical gas detectors
- Limited Lifespan: Typically, 1–3 years, depending on gas and environment.
- Temperature & Humidity Sensitivity: Extreme conditions can affect performance.
- Cross-Sensitivity: Some interference from similar gases.
- Calibration Requirements: Regular calibration needed for accuracy.
Summary
Electrochemical sensors are a cornerstone of ambient gas detection, offering precise and selective monitoring of toxic gases. While they are highly effective for safety and environmental applications, proper maintenance and calibration are essential to ensure long-term reliability.
Link to Case Study – Ambient sulphur dioxide (SO2) gas detection system installed in an FGD plant. | CEM Solutions
