Birefringent porous glass integrated between two plastic optical fibers terminated by crossed Polaroid™ films was used as a low-cost end-of-service-life indicator (ESLI) for organic vapor cartridges. Birefringence is significantly reduced when volatile compounds condense into the anisotropic porous structure. Such changes could easily be quantified using a low-cost light source and detector and very simple light intensity analysis. We showed that such sensors integrated into an experimental organic vapor cartridge could easily detect the progression of low concentrations of solvents (such as 50 ppm of toluene) into the activated charcoal cartridge and thus truly be used as an ESLI. Since such robust sensors could detect broadband solvents by simple physical condensation similar to the trapping phenomena of activated carbon, they are probably ideal candidates for such application.
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