Solution-based fabrication of gold grating film for use as a surface plasmon resonance sensor chip

Imprinted solution-processible gold nanoparticle (AuNP) grating films were fabricated for use as a grating-coupled surface plasmon resonance (SPR) excitation substrate. The imprinted AuNP grating pattern, which consists of a 1.72 μm grating pitch, was fabricated on flat glass substrates by imprinting AuNP on silicon grating templates. In this study, the SPR measurements were carried out on an SPR device in the grating-coupling configuration with a He-Ne laser (λ = 632.8 nm) as the excitation source, and multimode surface plasmon excitations were observed upon irradiation with white light. SPR excitation of our substrate was observed at the incident angle of 47.1°. For SPR measurements using white light irradiation, multimode surface plasmon excitation resulting from several diffraction orders was observed in the wavelength region of 500-850 nm. The surface plasmon dispersion branches were calculated to obtain the diffraction order in this region. SPR excitation of the imprinted AuNP grating substrate was further studied by fabrication of a layer-by-layer ultrathin film of iron containing bis(terpyridine) polymer (Fe(II)-BTP) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). A shift of the SPR excitation spectrum was observed when the ultrathin film was deposited on the imprinted AuNP grating surface. Thus, this substrate should be a useful SPR substrate in a variety of applications such as photoelectric conversions and sensors.