Planar integrated optical waveguide sensor for isopropyl alcohol in aqueous media

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

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


An attenuated total reflection (ATR) sensor for water-miscible organic solvents was constructed using a combination of sol-gel processing and integrated optical waveguide (IOW) technologies. The sensor consisted of single-mode, sol-gel based planar waveguide coated with a 40 nm thick, porous sol-gel indicator layer prepared from methyltriethoxysilane and doped with methyl red. The response of the senor to aqueous isopropyl alcohol (IPA) was investigated. Solvation of the indicator dye by IPA causes the absorbance spectrum to undergo a blue shift coupled with an increase in molar absorptivity. IPA was detected by measuring changes in ATR of the guided mode at 488 nm. A response curve extending from 1 to 100% (v/v) IPA in water was constructed for the sensor, from which a detection limit of 0.7% (v/v) IPA/water was estimated. Response and reversal times were typically less than one minute, making this sensor potentially attractive for on-line monitoring applications. The rapid response characteristics are attributable to relatively weak, reversible interactions between the indicator and analyte.

Original languageEnglish (US)
Pages (from-to)167-173
Number of pages7
JournalJournal of Sol-Gel Science and Technology
Issue number2
StatePublished - Jun 2002
Externally publishedYes


  • Attenuated total reflection (ATR)
  • Chemical sensor
  • Planar waveguide
  • Polarity-sensitive dye

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • General Chemistry
  • Biomaterials
  • Condensed Matter Physics
  • Materials Chemistry


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