Electrochemical gas sensors

SGX electrochemical gas sensors detect gases by producing a chemical reaction between the gas and oxygen contained in the sensor. This reaction produces a small current, which is proportional to the concentration of the gas present. Reactions occur on two electrodes which when combined together produce the sensing process. These electrodes comprise small discs of porous PTFE onto which is deposited a thin layer of a catalytic metal.

On the working electrode the target gas (carbon monoxide or hydrogen sulfide) react with water to product either carbon dioxide or sulfuric acid. On the counter electrode, hydrogen ions and 2 electrons, oxygen reacts with hydrogen ions and electrons to form water, e.g.

Because the electrodes have a finite catalytic activity (which can change with time and temperature) it is necessary to limit the rate of diffusion of target gas into the sensor (using a barrier) to ensure the gas is efficiently reacted. This barrier takes the form of a small hole or capillary in the sensor housing (see image below)

The electrodes need to be kept apart and wetted with an acid electrolyte to allow an ionic current to pass between them. This is done using discs of inert absorbent material or separators. These can be made from materials such as fiber glass.

The electrodes are connected to the external circuitry by thin metal strips or current collectors, attached to the pins.

Electrochemical Gas sensors benefits

  • Uses very little power
  • Show good responses to various gas concentrations over a wide range of ambient conditions
  • Range of 20mm electrochemical gas sensors for several toxic gases including; carbon monoxide, hydrogen sulfide and oxides of nitrogen and sulfur.
  • Drop-in replacement for existing sensor types in this size
  • RoHS compliant sensors
  • Unique EC410 gas sensor
  • New range of 32mm electrochemical gas sensors
  • Innovative combined carbon monoxide and hydrogen sulfide sensor in one package

Product range

Part Number DescriptionDatasheet
Electrochemical Cells
EC410Oxygen SensorDownload
EC4-100-H2S4 series H2S gas sensor 100ppmDownload
EC4-1000-H24 series H2 gas sensor 1000ppmDownload
EC4-1000-H2S4 series H2S gas sensor 1000ppmDownload
EC4-20-NO24 series NO2 gas sensor 20ppmDownload
EC4-20-SO24 series SO2 gas sensor 20ppmDownload
EC4-200-CL24 Series Chlorine Sensor 200 ppm RangeDownload
EC4-2000-CO4 series CO gas sensor 2000ppmDownload
EC4-2000-NO4 series NO gas sensor 2000ppmDownload
EC4-2000-SO24 series SO2 gas sensor 2000ppmDownload
EC4-250-NO4 series NO gas sensor 250ppmDownload
EC4-500-CO4 series CO gas sensor 500ppmDownload
EC4-1-CLO24 series Cholrine dioxide gas sensor 1ppmDownload
EC4-50-CLO25 series Cholrine dioxide gas sensor 50ppmDownload
Electrochemical Sensors
SGX-4OX4 series Oxygen sensor 0-25% 2 year lifeDownload
SGX-4CO4 series CO sensor - commercial gradeDownload
SGX-4H2S4 series H2S sensor - commercial gradeDownload
SGX-7NH37 series Ammonia sensorDownload
SGX-7OX7 series O2 sensor for fixed applicationsDownload
SGX-7CO7 series CO sensor for fixed applicationsDownload
SGX-7H2S7 series H2S sensor for fixed applicationsDownload
SGX-4DT4 Series Dual-Tox CO/H2S sensor - commerical applicationsDownload
SGX-4NH34 Series Ammonia sensorDownload
SGX-4NO24 Series Nitrogen Dioxide sensor