Multiplexed optical fiber sensors for humidity and chemical analysis

We report a novel approach to the fabrication of multiplexed optical fiber-based humidity and chemical sensors based on the molecular-level self-assembly of multilayered thin films that consist of several discrete segments through their thickness. As part of previous work, our groups have cooperatively demonstrated the formation of such self-assembled sensor thin films on optical fibers for the detection of humidity, and for the detection of chemical species. The layer-by-layer deposition of the alternating polyelectrolyte species used for each of these sensors independently has been discussed in several related papers. Here we have investigated the formation of multiple thin film sensor segments, one on top of the other, on the end of a singlemode optical fiber. The polymers and nanoclusters in each of the segments make them react differently to different chemical species. Together the segments form a spectral filter on the end of the fiber. We have investigated multiplexing and report initial experimental results.