Zero Drift Optical O2 Sensors, drift free fiber optic Oxygen Sensors
Zero Drift Sensors are the most stable, optical based oxygen sensors available anywhere. 
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*** Zero Drift Sensors work with Neofox electronics and all fiber assemblies from Ocean Optics ***

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Dissolved Oxygen (DO)  SensorsProcess Oxygen Sensors | pO2 SensorsOptical O2 Sensors for Fuels
 Phase Fluorometer Electronics| Optical O2 Sensor Application Notes | ZeroDrift Sensors Story | Technical Documentation & Software Downloads |

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Optical O2 sensing -

Applications, Documentation and Software

Optical O2 sensing Tips & Tricks 

There are many tricks and techniques that can help you obtain quality data from your optical O2 system. We are pleased to discuss your application with you, and are prepared to offer suggestions. Here are a few general tips:

 •Optical oxygen sensors respond to the partial pressure of O2, not O2 concentration. To calculate O2 concentration in gases, you need to know the total pressure. To calculate [O2] In liquids you need to know the Henry's Law coefficient. DO or dissolved O2 in water is the most common use for optical O2 sensors. To calculate the optical O2 concentration, we need to know temperature. This is because the solubility of O2 in water varies considerably with temperature.
Air is 20.94% O2 by concentration, but you need to know total pressure to calculate O2 partial pressure if you are using air as one of your standard gases to calibrate your optical oxygen sensor. NEOFOX has an onboard pressure monitor for ambient pressure. If your probe is not at ambient pressure (if it's deployed in a tank or pipe for example) then you will need to measure the pressure independently.
Temperature is critical. The optical O2 probe is slightly more sensitive to temperature than pO2. You can use the NEOFOX-TP probe to measure temperature, use the built in thermistors in our FT or RCT series optical O2 probes, or enter temperature by hand. We like to know the temperature to about +/- 0.1C.
NEOFOX provides for a "single point reset." This will change the intercept of the calibration so that the system will read the correct value at a single O2 level (for example air). This is only an approximation. Your single point reset is by definition perfect at the reset point, but the error grows the further you get from that point.
•Our AP chemistry is not affected by water vapor. The older FOXY, HIOXY and FOSPOR formulations are affected by water vapor and are not reccomeded. This will lead to errors if you calibrate in dry gases, and then use the probes in moist environments.
•If you don't have access to calibration gases, you can use chemicals to create O2 free samples. Sodium hydrosulfite added to water will scavenge all O2. If you are in a bind, room temperature carbonated beverages are pretty near zero as well, at least when you first open them. Yeast and sugar can also be used to create zero oxygen environments.
•The optical O2 sensor is more sensitive to changes in pO2 at low pO2 values. Sensitivity decreases as pO2 increases, and as temperature increases.
•Dissolved O2 concentration is a little tricky. pO2 and concentration are directly related for a liquid at a set temperature, but Henry's Law coefficient changes with temperature as well as media. You must have a temperature probe, or enter the temperature manually to activate the concentration views in NEOFOX VIEWER software.
•The HCR optical O2 probe stands up well to most organic solvents. However, many solvents also have an effect on the sensor signal. This is a reversible, reproducible quenching that can be removed from consideration by calibrating the probe in the solvent. Soak your HCR probes in the target solvent for an hour or so before calibrating. 
•Signal to noise varies with the intensity of the fluorescence signal. Bigger fibers are better than smaller fibers in terms of optical O2 signal strength.
•The fluorescence decay is in principle not affected by changes in intensity from fiber bending, ambient light, LED aging etc. Photobleaching does affect the observed tau in sol gel coatings such as FOXY. Our new AP formulation has dramatically reduced photobleaching drift to near zero.
• There are differences or offsets in Tau that occur from changes in signal intensity in the hardware. This includes moving a sensor to a new bifurcated fiber, and new Neofox unit, and also going from air to liquids where the refractive index matching will reduce the optical signal. These offsets can be compensated for with a single point reset. For the most accurate reliable data, calibrations on site with the existing hardware and sample media (liquid vs gases) are used. 

Applications  The optical O2 sensors can be used in a wide array of applications. These include monitoring a process, reaction, or biological activity. The fast response is critical for many rate measurements.   The sensors are excellent for low oxygen applications such as modified air packaging, inerting, and vacuum processes. The optical oxygen sensors are excellent for work in blood and tissues. The SEOX HCR probes are ideal for work in fuels, aircraft fuel tanks, transformer oil, petroleum pipelines, chemical processes carried out in solvents, biofuel production, enviroments with hydrocarbon vapors, etc. The HCR probes work well in all gases, breathing and respiration monitoring, capnography, etc. They do not react with water vapor. Probe design and construction is very flexible. We can design an optical DO or pO2 probe that will fit your application, from tiny sensors in needles to rugged probes for oil pipelines.

 Technical Documentation

Neofox User's Manual   Download as pdf

Neofox Analog & Digital Communications Guide  Download as pdf

Software Downloads

Additional Resources

Zero Drift optical O2 sensor - Spectrecology

Optical Zero Drift process oxygen control, fermentation, breweries, online measurements

Zero Drift SEOX sensors used in wastewater treatment plants

Optical DO sensors for Wastewater treatment plants

SEOX optical Oxygen sensors used in controlling water quality of fish farm tanks

Optical Dissolved oxygen sensing in Fish Farming

detecting O2 in modified air packaging MAP with Zero Drift optical O2 sensors

Insuring low O2 levels in  Modified Air Packaging with AP optical O2 sensor
Rutgers deap sea autonomous optical O2 sensors Spectrecology
Oceanographic -- optical dissolved oxygen in seawater, respiration rate measurements, marine sediments anoxic conditions...
Many More Applications:

Eye surgery - corneal O2 levels
Brain surgery - tissue oxygenation levels
Blood oxygenation - pO2 to SaO2
Vacuum processes - detecting leaks and trace amounts of O2
CO2 laser Cavities - leaks in CO2 detected as presence of oxygen
Chemical Reactors -- oxygen consumption
Fuel Tank Inerting -- O2 dissolved in fuels and in ullage of fuel tanks
OBIGGS and OBOGGS on aircraft -- O2 sensors for O2 supplied to F-22 pilots
Pilot Air Supply Safety -- OBOGGS failure alarm
pO2 in tree sap -- O2 in viscous samples
COD chemical oxygen demand
BOD biological oxygen demand
Primary Productivity -- oxygen production
Bio process control -- O2 and dissolved oxygen monitoring
Food Processing -- minimizing oxidation of foods, prevent spoilage
Food Packaging -- contamination sensor -- O2 consumption by bacteria

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