Abstract: The invention is a fluorescent sensor element for detecting concentration changes of oxygen in an atmosphere suitable for high temperature applications such as automotive exhaust gases. It comprises an optical fiber, preferably silica, coated on at least a portion of its surface with a sol-gel processed porous uniform mixture of (1) matrix material of alumina, zirconia, titania, or silica or a mixture of any of them with (2) ceramic fluorescent indicator like Cu-ZSM-5 zeolite incorporated therein. In use of the sensor element in a system, a light source excites fluorescence in the indicator which is responsive to varying oxygen concentration in the contacted exhaust gas.

Abstract: An on-board gas composition sensor is disclosed for monitoring oxygen content levels in the exhaust gas (24) of an internal combustion engine (4). The gas composition sensor includes a sensor body (20) mounted inan exhaust stream from an engine (4), with a fiber-optic cable (18) running from the sensor body (20) to a silicon chip (13) containing a sensor assembly(10). The sensor assembly (10) includes a light source (12), mounted on the chip (13), for generating excitation light. Also, a fiber-optic coupler (16), formed in the chip, operatively engages a second fiber-optic cable (15), mounted in a groove on the chip. The second cable (15) connects to a fluorescence detector (34) and an excitation detector (36). The two detectors produce output signals (35, 37) that are used by the electronic engine control (8) to adjust engine operation.