Electrochemical Sensors

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electrochemical sensors

The basic components of an electrochemical sensor are a working (or sensing) electrode, a counter electrode, and usually a reference electrode. These electrodes are enclosed in the sensor housing in contact with a liquid electrolyte. The working electrode is on the inner face of a Teflon membrane that is porous to gas, but impermeable to the electrolyte.

The gas diffuses into the sensor and through the membrane to the working electrode. When the gas reaches the working electrode, an electrochemical reaction occurs; either an oxidation or reduction depending on the type of gas. For example, carbon monoxide may be oxidized to carbon dioxide, or oxygen may be reduced to water. An oxidation reaction results in the flow of electrons from the working electrode to the counter electrode through the external circuit; and conversely a reduction reaction results in flow of electrons from the counter electrode to the working electrode. This flow of electrons constitutes an electric current, which is proportional to the gas concentration. The electronics in the instrument detects and amplifies the current and scales the output according to the calibration. The instrument then displays the gas concentration in, for example, parts per million (PPM) for toxic gas sensors and percent volume for oxygen sensors.

TRAINING DISCLAIMER: These training videos and other training materials are intended to assist employers, workers, and others as they strive to improve workplace health and safety, by educating them on the practical use of Industrial Scientific® gas detection equipment. While we attempt to thoroughly address the specific topics, it is not possible to include discussion of everything in a presentation of this nature. Thus, this information must be understood as a tool to assist you in the operation of your Industrial Scientific® gas detection equipment. Finally, over time, Industrial Scientific Corporation may update the training materials and videos in light of new technology, information, or circumstances; to keep apprised of such developments, or to review a complete and up to date library of our training materials, you can visit our website at www.indsci.com or download our app.

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