title: A bridged loop-gap S-band surface resonator for topical EPR spectroscopy.
abstract: The design and structure of a bridged loop-gap surface resonator developed for topical EPR spectroscopy and imaging of the distribution and metabolism of spin labels in in vivo skin is reported. The resonator is a one-loop, one-gap bridged structure. A pivoting single loop-coupling coil was used to couple the microwave power to the loop-gap resonant structure. A symmetric coupling circuit was used to achieve better shielding and minimize radiation. The frequency of the resonator can be easily adjusted by trimming the area of the capacitive foil bridge, which overlaps the gap in the cylindrical loop. The working frequency set was 2.2 GHz and the unloaded Q was 720. The B1 field of this resonator was measured and spatially mapped by three-dimensional EPR imaging. The resonator is well suited to topical measurements of large biological subjects and is readily applicable for in vivo measurements of free radicals in human skin.
authors.affiliation: The EPR Center and Division of Cardiology, Department of Medicine, The Johns Hopkins University School of Medicine, 5501 Hopkins Bayview Circle, Baltimore, Maryland 21224, USA.
authors.forename: S
authors.initials: S
authors.lastname: Petryakov
authors.forename: M
authors.initials: M
authors.lastname: Chzhan
authors.forename: A
authors.initials: A
authors.lastname: Samouilov
authors.forename: G
authors.initials: G
authors.lastname: He
authors.forename: P
authors.initials: P
authors.lastname: Kuppusamy
authors.forename: J L
authors.initials: JL
authors.lastname: Zweier
mesh_terms: D004574:Electromagnetic Fields; D004578:Electron Spin Resonance Spectroscopy / Q000295:instrumentation*; D005609:Free Radicals / Q000737:chemistry; D006801:Humans; D008872:Microwaves; D012867:Skin / Q000737:chemistry
chemical_list: D005609:Free Radicals