OxySense® for Non-Invasive Oxygen Measurement
OxySense® is the first non-invasive oxygen measurement system for sealed packages. It is tailored for the needs of the food, beverage, and pharmaceutical industries. The system is unique not only for its ability to measure oxygen non-invasively, but also for its ability to measure oxygen in headspace as well as in dissolved liquids. It is an optical system that can measure oxygen concentration within packages that are transparent, semi-transparent, and translucent; and as long as the packaging material can transmit blue and red light (at approximately 470nm and 610nm respectively), a measurement can be made.
Our technology relies on a non-invasive, light sensitive, oxygen sensor that we call the The Oxy2®. Placed in Packages prior to filling, measurements are achieved simply with a fiber-optic reader pen from outside the package.
The Advantages of OxySense®
The advantages of OxySense® include:
- Non-destructive measuring technique
- Thousands of measurements per package
- Fast measurements (< .1 second)
- Accuracy at ambient, 5% of the reading
- Reproducibility is better than 1% (0.2% O2)
- Sterilization tested up to 150°C (1sp hr.), can withstand pasteurization
- Can be used in oil, water and air
- Independent of pH (2-12) and salt concentration
- No interference from other gases
OxySense® vs. Traditional Measurement Techniques
The measurements made using OxySense® have greater than 98% correlation with measurements made using Gas Chromatograph.
Sensing Oxygen Within a Package
To sense oxygen within a package, an Oxy2Dot® is attached to the inside of the package. The dot is illuminated with a pulsed blue light from an LED. The blue light is absorbed by the dot and red light is emitted. The red light is detected by a photo-detector and the characteristics of the fluorescence lifetime is measured. Different lifetime characteristics indicate different levels of oxygen within the package.
The OxySense® fiber optic reader-pen assembly contains both a blue LED and photodetector to measure the fluorescence lifetime characteristics of an Oxy2Dot® within a sealed container.
The Oxy2Dot® and Fluorescence
The oxygen measurement technique is based upon the fluorescence quenching of a metal organic fluorescent dye immobilized in a gas permeable hydrophobic polymer. The dye absorbs light in the blue region and fluoresces within the red region of the spectrum. The presence of oxygen quenches the fluorescent light from the dye as well as its lifetime. The quenching process is a purely collisional dynamic where the energy from the excited fluorescent dye is transferred to the oxygen molecule during a collision, hence, reducing the emission intensity as well as the fluorescent lifetime of the dye. Thus, the oxygen content of the enclosed space is not changed by the measurement process.
Fluorescence Decay and Oxygen Measurement
The change in the emission intensity and lifetime is related to the oxygen partial pressure and can be calibrated to determine the oxygen concentration. The measurement is passive, totally reversible and no oxygen is consumed in the process.
The fluorescence lifetime is reduced due to the presence of oxygen; this change can be calibrated to make a powerful sensor that has a large dynamic range.