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Updated: Apr 27, 2026

Fast and Accurate Exhaled Breath Ammonia Measurement
Published on: June 11, 2014
Coumarin meets fluorescein: a Förster resonance energy transfer enhanced optical ammonia gas sensor
Susanne Widmer1, Marko Dorrestijn, Agathe Camerlo
1Empa, Swiss Federal Laboratories for Material Science and Technology, Laboratory for Protection and Physiology, Lerchenfeldstr. 5, 9014 St. Gallen, Switzerland. Susanne.Widmer@empa.ch.
Abstract:
This study focuses on the development of an optical ammonia gas sensor, the sensing mechanism of which is based on Förster resonance energy transfer (FRET) between coumarin and fluorescein. The dyes were immobilized into an organically modified silicate matrix during polymerizing methyltriethoxysilane with trifluoropropyltrimethoxysilane on a poly(methyl methacrylate) substrate. The resulting dye-doped xerogel films were exposed to different gaseous ammonia concentrations. A logarithmic decrease of the coumarin fluorescence emission band at 442 nm was observed with increasing gaseous ammonia concentrations, which was due to enhanced FRET between coumarin and fluorescein. The coumarin/fluorescein composition was optimized in order to obtain the best ammonia sensitivity. First experiments in a flow cell gas sensor setup demonstrated a sensitive and reversible response to gaseous ammonia.
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