title: Biomolecular sensors utilizing waveguide modes excited by evanescent fields.
abstract: Properties of evanescent-field-coupled waveguide-mode sensors consisting of a multi-layer structure made of a SiO(2) waveguide, a thin metal layer (Au, Cu, W or Ti), and a high refractive index glass substrate illuminated under the Kretschmann configuration have been theoretically and experimentally investigated. In all cases, reflectivity changes attributed to streptavidin combining to biotinyl groups were observed in close spectral vicinity of the waveguide resonances. The sensors with the Au and the Cu layers show superior sensitivity as compared to those with the W and the Ti layers, whereas the W and Ti layers show better thermal and chemical stability. The results indicate that the materials of thin metal layers should be chosen in accordance with the purpose of sensors and/or environment in which the sensors are used.
authors.affiliation: Center for Applied Near-Field Optics Research (CAN-FOR), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8562, Japan. m-fujimaki@aist.go.jp
authors.forename: M
authors.initials: M
authors.lastname: Fujimaki
authors.forename: C
authors.initials: C
authors.lastname: Rockstuhl
authors.forename: X
authors.initials: X
authors.lastname: Wang
authors.forename: K
authors.initials: K
authors.lastname: Awazu
authors.forename: J
authors.initials: J
authors.lastname: Tominaga
authors.forename: T
authors.initials: T
authors.lastname: Ikeda
authors.forename: Y
authors.initials: Y
authors.lastname: Koganezawa
authors.forename: Y
authors.initials: Y
authors.lastname: Ohki
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D001710:Biotin / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods*; D055095:Optics and Photonics; D012031:Refractometry / Q000379:methods*; D012822:Silicon Dioxide; D019809:Streptavidin / Q000737:chemistry*
chemical_list: D001710:Biotin; D012822:Silicon Dioxide; D019809:Streptavidin