Humidity-sensitive optode membrane based on a fluorescent dye immobilized in gelatin film

Martin M F CHOI*, Oi Ling Tse

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

74 Citations (Scopus)


Humidity-sensitive optode membranes have been fabricated by immobilizing rhodamine 6G and ethylene glycol-water mixture into gelatin matrix deposited on overhead transparency films. The optode membrane shows the strong fluorescence at 568nm when it is excited at 536nm. The fluorescence intensity at 568nm decreases with increasing relative humidity. It exhibits a wide linear dynamic range from 10.2% to 100% relative humidity and also shows a good linearity (correlation coefficient is 0.9952) at 20.0°C and atmospheric pressure. Both the exposure time and recovery time of the optode membrane are 1min. The sensor has good reproducibility, photostability and long-term stability. Oxygen and carbon dioxide gases do not show any interference. Acetone, toluene vapours and NO(x) have slight interferences whereas ethanol, chloroform, acetic acid vapours and SO2 cause serious interferences on the optode membrane. Copyright (C) 1999 Elsevier Science B.V.

Original languageEnglish
Pages (from-to)127-134
Number of pages8
JournalAnalytica Chimica Acta
Issue number1-3
Publication statusPublished - 4 Jan 1999

Scopus Subject Areas

  • Analytical Chemistry
  • Biochemistry
  • Environmental Chemistry
  • Spectroscopy

User-Defined Keywords

  • Gelatin
  • Humidity sensor
  • Rhodamine 6G


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