Patches for non-intrusive monitoring of oxygen in packages
This disclosure describes an Oxygen sensing patch that can be attached to the interior surface of packages for oxygen interrogation inside the package. The Oxygen sensing patch is integrated into the inside of the package during the packaging manufacturing process and, when used with a blue LED and fluorometer, will quantitatively report the amount of oxygen in the package. The Oxygen sensing patch is suitable for measuring oxygen in gas, such as headspace applications, and in liquid. Oxygen is sensed by measuring the phase shift of fluorescence of the fluorophore immobilized in the Oxygen sensing patch. The patch can be non-intrusively interrogated by a light source. The interrogation can be done using a phase fluorometer where oxygen level is desired, or inspected visually for color change using a hand held blue LED.
1. An Oxygen sensing patch using fluorescence quenching for sensing Oxygen in liquids or gases that can be used inside an enclosed area or container such as product packaging comprising: a flexible patch with adhesive on one side such that said flexible patch can be placed and held on a surface inside an enclosed area or container containing a gas or liquid to be measured for Oxygen content wherein said flexible patch is a poly acrylate consisting of 3.0 mil (76 micron) self-adhesive poly acrylate with 20 micron high track acrylic adhesive and 38 micron polyester liner; a sol gel matrix of organically modified silica that is made from a mixture comprising sol gel precursors, that is doped with a ruthenium or porphyrin complex and coated on the side of said flexible patch without the adhesive and then cured; and, said enclosed area or container having a clear area or window such that blue light can be shown through said clear area or window onto said flexible patch and fluorescence from said ruthenium or porphyrin complex contained in said sol gel matrix can be detected through said clear area or window to measure the partial pressure of dissolved or gaseous Oxygen.
2. The Oxygen sensing patch of claim 1 wherein said sol gel mixture prior to being doped and cured, comprises a mixture of sol gel precursor MTMS (methyltrimethoxysilane, MTMS), fluorinated sol gel precursor [(3,3,3-trifluoropropyl)triethoxysilane], water, and ethyl alcohol.
3. The Oxygen sensing patch of claim 1 wherein said ruthenium complex consists of tris-(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) chloride.
4. The Oxygen sensing patch of claim 1 wherein said sol gel matrix that is doped with a ruthenium or porphyrin complex is coated on said flexible patch by spin coating and is then thermally and optically cured.