Ocean Optics will determine the feasibility of using Plasma Assisted Surface Modification (PLASM) to add chemical resistance to its current fluorescence based oxygen sensor to meet the requirements of the fuel tank monitoring environment. The effort will focus on: Modifying our existing sol-gel formulation to eliminate the leaching of fluorescence material; Developing high performance overcoats of Teflon or other candidate materials to block armomatic hydrocarbon vapors; Perfecting fabrication techniques, materials and designs that provide a mechanically stable probe over the extremes of temperature and pressure encountered by aircraft. The results of Phase I studies will be used in Phase II to develop a flight worthy oxygen sensor that can be used with Onboard Inerting Systems to protect fuel tanks from explosions caused by ballistics, lightning or other sources of ignition. Successful development of an oxygen optical sensor that meets the fuel tank environment requirements will have direct impact on the safety of fuel tanks against explosions in both military as well as commercial jets. Ocean Optics and its commercial partners intend to develop an Onboard Fuel Tank Inerting System for commercial aircraft, to prevent accidents such as TWA 800 and ValueJet. The oxygen sensor is a critical component of this system. Military applications include combat aircraft, in-flight refueling tankers, and the M1 tank. The sensor will also be sold for polymer process control, modified air packaging for pharmaceuticals and foods and in-vivo medical use.