LED drives low-cost oxygen sensor

An oxygen sensor that can withstand fluctuations in temperature, salinity, CO2, phosphates and biological wastes can also provide real-time data at a low cost, according to Ruby Ghosh, associate professor of physics at Michigan State University (MSU; East Lansing, MI), who developed it.

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By Lee Mather

An oxygen sensor that can withstand fluctuations in temperature, salinity, CO2, phosphates and biological wastes can also provide real-time data at a low cost, according to Ruby Ghosh, associate professor of physics at Michigan State University (MSU; East Lansing, MI), who developed it.

Industries that benefit from oxygen sensing include biomedical research, which could use probes to further cancer research by detecting changes in oxygen dependence in relation to tumor growth, and aquaculture, where fish are raised in oxygen-rich, high-density environments. Biomedical application, however, is still in its preliminary stages, Ghosh told BioOptics World.

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Biomedical application of an LED-based dissolved oxygen sensor is still in preliminary stages. (Image courtesy of Greg Kohuth)

Ghosh built prototypes of the oxygen sensor in her MSU lab; to test them, she and her students worked with Michigan fish farmers to see how they would hold up in a year-round, outdoor environment, as raising trout for recreational fishing is economically important to Michigan. “…our prototype proved that our sensor performs well in the field and could help that industry thrive,” says Ghosh.

The oxygen sensor incorporates a UV light-emitting diode (LED) with a color glass filter used as the pump beam, eliminating the need for a monochromatic excitation source, and a silicon (Si) avalanche photodiode (APD) with a 600-nm-long wavelength filter. The sensor can monitor phosphorescence or emission lifetime using phase-sensitive techniques, which can be implemented using a simple phase-locked loop configuration as opposed to a bulky optical fluorometer.

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