Satoshi Araki

Directed growth of metal nanoparticles on substrates by polarized light irradiation

Sensitivity of optical sensing can be enhanced using assistance of plasmon generated at metal nanostructures, like SERS-based sensing. The growth process of metal nanoparticles which can control both shape and orientation on substrates in one step is required to solve the problem of the arrangement of pre-synthesized metal nanorods or other nanostructures to the surface of substrates in specific orientation. In this study, the procedure of polarized-light-directed growth of metal nanoparticles fixed on glass substrates in direct way is proposed, in which the irradiation of linearly polarized light to pre-deposited gold seeds on substrate, in immersing the substrates in the growth solution containing metal cations (gold or silver ions) and reducing agents. Consequently the anisotropic nanostructures whose orientation angle was in accordance with polarization direction in growth process were obtained. The evaluation of the resulted structures was performed with UV-vis spectrometer and scanning electron microscope.

Raman enhanced structure with reconfigured molecularly-imprinted-polymer for gas deteciton

Various devices are developed to obtain information of odor for crisis evasion in dangerous situation. However, the improvement of sensing methodology is lagging. Therefore, some novel odor sensors with high sensitivity, selectivity and short response time are required. Gas detection based on surface enhanced Raman scattering (SERS) is a promising technology to realize such sensor. We developed a sandwich structured SERS substrate with an organic layer, which was placed between an Au thin layer and a gold nano particles (AuNPs) layer. Furthermore, the organic layer was reconfigured to molecularly imprinted polymer (MIP) for selective gas detection. Raman spectrum obtained with a MIP-SERS substrate shows the appearance of peak based on 2-phenylethanol that is targeted gas molecule. Compared with non-imprinted polymer (NIP), MIP substrate showed stronger SERS signals.