Sol-gel-based, planar waveguide sensor for water vapor

Peter J. Skrdla, S. Scott Saavedra, Neal R. Armstrong, Sergio B. Mendes, N. Peyghambarian

Research output: Contribution to journalArticlepeer-review

44 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)1332-1337
Number of pages6
JournalAnalytical Chemistry
Issue number7
StatePublished - Apr 1 1999

ASJC Scopus subject areas

  • Analytical Chemistry


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