title: Magnetic-resonance evaluation of the suitability of microstructured polymer optical fibers as sensors for ionic aqueous solutions.
abstract: Nuclear magnetic resonance was used to probe the distribution of water and ionic species in a microstructured poly(methyl methacrylate) (PMMA) polymer optical fiber (MPOF), with a plan to assess the suitability of these fibers for aqueous chemosensing. The NMR spectra and the measurements of proton spin relaxation in hydrated fibers demonstrated the presence of two distinct pools of water: water residing in the microstructure channels and the hydration water residing in the polymer matrix of the fiber. No facile chemical exchange between these two pools was present. The NMR peaks of the two pools of water were separated by 1.53 ppm. Relaxation measurements of the fiber samples doped with aqueous copper sulfate showed that charged ions freely entered the microstructure channels but were completely excluded from the polymer matrix of the fiber. Measurements of the apparent diffusion coefficient of water along the axial direction of the fiber showed that water molecules moved unimpeded along the channels. This is the first reported magnetic-resonance study of microstructured optical fibers. The findings suggest that microstructured PMMA fibers are compatible with ionic aqueous solutions and could provide a robust and durable platform for chemical-sensing applications.
authors.affiliation: Optical Fibre Technology Centre and School of Molecular and Microbial Biosciences, University of Sydney, New South Wales 2006, Australia, and School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001, Australia.
authors.forename: Felicity M
authors.initials: FM
authors.lastname: Cox
authors.forename: Konstantin I
authors.initials: KI
authors.lastname: Momot
authors.forename: Philip W
authors.initials: PW
authors.lastname: Kuchel
mesh_terms: D019327:Copper Sulfate / Q000737:chemistry; D016014:Linear Models; D055616:Microtechnology / Q000379:methods; D015336:Molecular Probe Techniques; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D055100:Optical Fibers; D019904:Polymethyl Methacrylate / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water; D019904:Polymethyl Methacrylate; D019327:Copper Sulfate