title: Coumarin meets fluorescein: a Förster resonance energy transfer enhanced optical ammonia gas sensor.
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.
authors.affiliation: Empa, Swiss Federal Laboratories for Material Science and Technology, Laboratory for Protection and Physiology, Lerchenfeldstr. 5, 9014 St. Gallen, Switzerland. Susanne.Widmer@empa.ch.
authors.forename: Susanne
authors.initials: S
authors.lastname: Widmer
authors.forename: Marko
authors.initials: M
authors.lastname: Dorrestijn
authors.forename: Agathe
authors.initials: A
authors.lastname: Camerlo
authors.forename: Špela Korent
authors.initials: ŠK
authors.lastname: Urek
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Lobnik
authors.forename: Catherine E
authors.initials: CE
authors.lastname: Housecroft
authors.forename: Edwin C
authors.initials: EC
authors.lastname: Constable
authors.forename: Lukas J
authors.initials: LJ
authors.lastname: Scherer