Detection Principle of British DDS Electrochemical Gas Sensors
What is a Gas Sensor?
A gas sensor is a device that detects the presence of gas and measures its concentration by converting physical or‑chemical interactions into electrical signals. These signals are processed and expressed in standard units such as ppm, %LEL or %Vol.
Gas sensors are widely used in industry, environmental monitoring, medical systems, transportation and residential buildings. They are designed to monitor flammable gases, toxic gases, oxygen levels, as well as natural‑gas leaks in open‑air and confined spaces.
From an engineering perspective, gas sensors are more than just sensing elements. They are complete systems integrating gas‑diffusion control, signal processing, environmental compensation and long‑term stability management to guarantee reliable and accurate measurements.
Types of Gas Sensors
There are various types of gas sensors. Selecting an appropriate sensor requires understanding sensor characteristics, target gases, operating environment and long‑term stability requirements. Typical user concerns include: which sensors offer selectivity for toxic gases, which deliver high measurement accuracy, which support portable operation, and which are suitable for continuous fixed‑point monitoring.
By target gas type, sensors are categorized into flammable‑gas sensors (typically catalytic‑bead, infrared, thermal‑conductivity, semiconductor), toxic‑gas sensors (commonly electrochemical, metal‑oxide semiconductor, photoionization sensors), oxygen sensors (paramagnetic, zirconia sensors), and special‑purpose industrial sensors.
By operating mode, they fall into portable detectors and fixed online detectors.
By sampling method, they are diffusion‑type sensors and pump‑driven sensors. Diffusion‑type sensors rely on gas diffusing naturally to the sensing element. Pump‑driven sensors actively draw gas into the measurement chamber for faster response and remote sampling capability.
By detection principle, gas sensors include semiconductor, electrochemical, infrared (NDIR), catalytic, thermal‑conductivity, magnetic, photoionization (PID), acoustic / photoacoustic and other specialized sensing technologies.
Classification based on working principle is a widely‑adopted approach. Below we elaborate on electrochemical gas sensors, covering their working principle, advantages and typical applications:
Electrochemical Gas Sensors
Electrochemical sensors react with target gases and generate electrical signals proportional to gas concentration. Most electrochemical gas sensors are amperometric current‑measuring devices, whose output current has a linear relationship with gas concentration.
Working principle of electrochemical gas sensors: Gas first passes through a porous dust‑proof breathable membrane to prevent condensation and dust from entering the sensor. Gas molecules then diffuse through filter layers and reach the working electrode, where oxidation or reduction reactions take place. These electrochemical reactions alter the current flowing through the external circuit, and the current change is proportional to gas concentration.
Electrochemical‑principle sensors adopt 3‑electrode or 4‑electrode configurations, consisting of working electrode, reference electrode, counter electrode and auxiliary electrode, to improve stability and linearity. A simpler 2‑electrode structure is also used in some cases.
Advantages
High sensitivity, excellent linearity, low power consumption, and good selectivity toward specific toxic gases.
Electrochemical sensors are extensively deployed in portable and fixed monitoring instruments for detecting O₂ (oxygen), CO (carbon monoxide), H₂S (hydrogen sulfide), SO₂ (sulfur dioxide), NOₓ (nitrogen oxides), NH₃ (ammonia), H₂ (hydrogen), Cl₂ (chlorine), O₃ (ozone) and other gases.
If you have gas‑detection requirements, first confirm the target gas species and then pick the optimal measurement principle. For instance, catalytic‑bead or NDIR principles perform better for flammable gases (methane, propane, hydrogen), while electrochemical principle works most effectively for toxic gases (CO, H₂S, NH₃). Secondly, determine required accuracy, service life, and whether waterproof, explosion‑proof or alarm functions are needed according to measurement environment and application scenarios.
