Concept
National Marine Facilities Microelectrode Oxygen Sensor
| URI | http://vocab.nerc.ac.uk/collection/L22/current/TOOL0405/1/ | ||
|---|---|---|---|
| Within Vocab | SeaVoX Device Catalogue | ||
| Alternative Labels | NMF Microelectrode DO | ||
| Definition | A non-membrane dissolved oxygen sensor for marine applications. The sensor uses a platinum microelectrode and a counter electrode (thus far composed of copper). A measurement potential is applied to the microelectrode relative to a counter electrode, reducing the dissolved oxygen in the water and generating a current through the microelectrode proportional to the number of oxygen molecules at that electrode. The sensor was first used in 2000 and development is ongoing. Early versions of the instrument applied the measurement potential for up to 30 seconds, with sampling starting approximately one second after the potential was applied. The sensor response to oxygen remained almost constant for a given concentration and data could be sampled at frequencies exceeding 1 Hz. To reduce noise generated by sensitivity to flow fluctuations a mesoporous layer was used to increase the surface area of the microelectrode, but this proved unstable and was replaced by a stop-flow system which pumped water in to a very small chamber, with measurements being taken while the water was still. This significantly improved results but the sensor was still affected by small convection currents. The current version of the sensor only applies the measurement potential for a few 10s of milliseconds and data are collected at approximately 1 Hz in an attempt to minimise the effects of convection currents. The latest development is a very small sensor head containing an array of microelectrodes (currently an array of five) that work together. The counter electrode consists of silver or silver chloride. This is currently undergoing trials and is yet to be deployed on a CTD profiler. | ||
| Date | 2011-07-27T13:50:44 | ||
| Identifier | SDN:L22::TOOL0405 | ||
| Note | accepted | ||
| Is Version Of | TOOL0405 | ||
| version | 1 | ||
| Broader | L05:351 |
dissolved gas sensors | |
L19:SDNKG17 |
sensor_model | ||
| Related | B75:ORG00125 |
Natural Environment Research Council, National Marine Facilities Sea Systems | |
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