Multi-gas differentiation using an individual optical fiber sensor with a chemically modified cladding

Today, differentiation of volatiles in complex environments is done using traditional analytical instruments, designed with one or more independent response variables. An emerging competing technology is individual first-order gas sensors (a.k.a. multivariable sensors). Here we expand individual first-order gas sensors from known electrical circuits, mechanical resonators, and photonic nanostructures to first-order fiber-optic evanescent wave sensors. With an individual first-order fiber-optic sensor, we differentiate multiple volatiles by chemically modifying an original silicone cladding of a plastic-clad silica fiber and guiding high order modes in the optical fiber. Our approach for building first-order fiber-optic sensors can be attractive for detection of analytes in air and water and for spatial analyte mapping over extended, remote areas.