Abstract: A sensing apparatus for detecting at least one target molecule in a gaseous medium is provided, comprising an optical fiber having a core with a tilted grating, and a coating assembly. The coating assembly has a composite film layer having an outer surface in direct contact with the gaseous medium, and contains at least two compositions mixed with one another therein, which include one or more surface plasmon resonance (SPR)-active compositions and one or more reacting compositions that are reversibly reactive to the at least one target molecule. Depending on different reacting compositions, the sensing apparatus can detect various target gas molecules such as hydrogen, ammonia, methane, and formaldehyde, etc. The sensing apparatus has relatively fast response time and high resistance to deactivation. A sensing system based on the sensing apparatus, a manufacturing method of the sensing apparatus, and a detection method using the sensing system, are further provided.

Abstract: A sensing apparatus for detecting at least one target molecule in a gaseous medium is provided, comprising an optical fiber having a core with a tilted grating, and a coating assembly. The coating assembly has a composite film layer having an outer surface in direct contact with the gaseous medium, and contains at least two compositions mixed with one another therein, which include one or more surface plasmon resonance (SPR)-active compositions and one or more reacting compositions that are reversibly reactive to the at least one target molecule. Depending on different reacting compositions, the sensing apparatus can detect various target gas molecules such as hydrogen, ammonia, methane, and formaldehyde, etc. The sensing apparatus has relatively fast response time and high resistance to deactivation. A sensing system based on the sensing apparatus, a manufacturing method of the sensing apparatus, and a detection method using the sensing system, are further provided.

Abstract: A sensing apparatus, system, and use method for selective detection of a target molecule in a gaseous medium with a limit of detection of less than 50 ppm are provided. The sensing apparatus comprises an optical fiber having a core with a tilted grating, and a coating assembly that is both active to surface plasmon resonance (SPR) and reversibly reactive to the target molecule to allow for repeated detection. Upon a compatible light propagating in the optical fiber, surface plasmon waves at an interface between the coating assembly and the medium can be generated to thereby derive information of the target molecule. Signals from core mode optical waves can additionally be used as inherent reference to remove influences of fluctuations from environmental factors and input power level. There is at least one range of concentrations for the target molecule allowing for linear measurement. Multiplexing of a plurality of sensing apparatuses is also disclosed.