title: An electroactive fiber optic chip for spectroelectrochemical characterization of ultra-thin redox-active films.
abstract: The first, fully integrated, planar fiber optic platform with spectroelectrochemical capabilities, termed the electroactive fiber optic chip (EA-FOC) is presented here. Spectroelectrochemical techniques provide complementary optical and electrochemical data which are important for applications ranging from thin film characterization to advanced sensor design. To create the EA-FOC a side-polished fiber optic is coated with a thin film of indium-tin oxide (ITO) as the working electrode and used to probe electrochemically-driven changes in absorbance for surface-confined redox species. A sensitivity enhancement of approximately 40 times higher than a transmission measurement is demonstrated for this first-generation EA-FOC, using the methylene blue (MB) redox couple, cycling between the visibly colored, oxidized form of MB, and its leuco (transparent) reduced form. Additionally, the EA-FOC is used to probe the redox spectroelectrochemistry of an electrodeposited thin film, about 0.3% of a monolayer, of the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT). Unlike other waveguide formats, the EA-FOC offers an ease of use due to its ability to simply couple to light sources and detectors through standard fiber connectors to create a sensitive planar waveguide spectroelectrochemical platform.
authors.affiliation: Department of Chemistry, University of Arizona, Tucson, Arizona 85721, USA.
authors.forename: Brooke M
authors.initials: BM
authors.lastname: Beam
authors.forename: Neal R
authors.initials: NR
authors.lastname: Armstrong
authors.forename: Sergio B
authors.initials: SB
authors.lastname: Mendes
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D055664:Electrochemical Techniques / Q000295:instrumentation / Q000379:methods; D004867:Equipment Design; D005336:Fiber Optic Technology / Q000295:instrumentation / Q000379:methods*; D008751:Methylene Blue / Q000737:chemistry; D010084:Oxidation-Reduction; D012680:Sensitivity and Specificity
chemical_list: D008751:Methylene Blue