title: Sol-gel-based, planar waveguide sensor for water vapor.
abstract: A water vapor sensor based on a combination of sol-gel processing and planar optical waveguide technologies has been developed. The indicator erythrosin B was entrapped in a thin sol-gel film (thickness ∼100 nm) prepared from methyltriethoxysilane, dimethyldiethoxysilane, and tetraethoxysilane. This dye exhibits an increase in absorbance in the presence of liquid or gaseous water. The sol-gel layer containing the dye was deposited onto a sol-gel-derived, single-mode planar waveguide. Outcoupled light intensity measurements (at 514.5 nm) over a range of water vapor concentrations (in a nitrogen gas stream) yielded a response over a wide range of relative humidity (<1-∼70%) at room temperature. Response and reversal times were less than 1 min, which may make this sensor attractive for real-time monitoring applications.
authors.affiliation: Department of Chemistry and Optical Sciences Center, University of Arizona, Tucson, Arizona 85721-0041.
authors.forename: P J
authors.initials: PJ
authors.lastname: Skrdla
authors.forename: S S
authors.initials: SS
authors.lastname: Saavedra
authors.forename: N R
authors.initials: NR
authors.lastname: Armstrong
authors.forename: S B
authors.initials: SB
authors.lastname: Mendes
authors.forename: N
authors.initials: N
authors.lastname: Peyghambarian