Viologen-based fiber optic oxygen sensors: optics development

Sensors for oxygen in liquids have been commonly used for clinical chemistry applications. Optical approaches to blood gas applications have been known for some time2. The opportunity for fiber sensor applications in this area is created by familiar fiber sensor advantages: small size, dielectric isolation, and the availability of a number of sensor chemistry systems3' 4. The overall sensor system is based on a viologen compound that changes absorbance as oxidation (or reduction) occurs. This compound responds to short wavelength light by darkening; the time for a return to the clear state depends on the amount of oxygen present.