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

EC4 series

A range of 20 mm electrochemical sensors is available for several toxic gases including Carbon Monoxide ,Hydrogen Sulfide and Oxides of Nitrogen and Sulfur. These sensors are ‘drop-in’ replacements for existing sensor types in this size.

The range of toxic sensors is complemented by the EC410 , RoHS compliant, Oxygen sensor. This unique sensor contains no lead, has a greatly increased life span and is of significantly lower mass compared to other Oxygen sensors of this size. The sensor contains no consumable components.

SGX series

SGX Sensortech are pleased to announce the launch of eight new sensors to complement their range of industrial and commercial gas sensing products.  The new products allow instrument manufacturers a greater choice when selecting sensors for carbon monoxide, hydrogen sulfide and oxygen and are available in two industry standard packages; 20mm and 32mm diameter.

In addition, SGX are proud to include an innovative combined carbon monoxide and hydrogen sulfide sensor in the same package which provides industry compliant performance in a single miniature housing, saving valuable space in portable instrument designs.

Product range

Part Number DescriptionDatasheet
EC410Electrochemical Oxygen SensorDownload
EC4-2000-SO2Electrochemical cell for Sulphur DioxideDownload
SGX-4OXElectrochemical cell for Sulphur DioxideDownload
SGX-4COElectrochemical cell for Carbon MonoxideDownload
SGX-4H2S-300Electrochemical cell for Hydrogen Sulphide Download
SGX-4DTDual Electrochemical cell for Carbon Monoxide and Hydrogen SulphideDownload
SGX-4CL24 series electrochemical cell for chlorineDownload
SGX-4ETO4 series electrochemical cell for ethylene oxideDownload
SGX-40X-ROHS4 series electrochemical lead free oxygen sensorDownload
SGX-7H2S-200Electrochemical cell for hydrogen sulphideDownload
SGX-4NH3-10004 series electrochemical cell for ammoniaDownload