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GOLD NANOPARTICLE PATTERNING BY SELF-ASSEMBLY AND TRANSFER FOR LSPR BASED SENSING

GOLD NANOPARTICLE PATTERNING BY SELF-ASSEMBLY AND TRANSFER FOR LSPR BASED SENSING. T. Ozaki, K. Sugano, T. Tsuchiya, O. Tabata Department of Micro Engineering, Kyoto University , Kyoto, JAPAN ADVISER: Dr .CHENG-SHINE-LIU REPORTER: SRINIVASU V P & HSIEH,HSIN-YI

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GOLD NANOPARTICLE PATTERNING BY SELF-ASSEMBLY AND TRANSFER FOR LSPR BASED SENSING

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  1. GOLD NANOPARTICLE PATTERNINGBY SELF-ASSEMBLY AND TRANSFER FOR LSPR BASED SENSING T. Ozaki, K. Sugano, T. Tsuchiya, O. Tabata Department of Micro Engineering, Kyoto University , Kyoto, JAPAN ADVISER: Dr .CHENG-SHINE-LIU REPORTER: SRINIVASU V P & HSIEH,HSIN-YI STUDENT ID: 9733881 & 9735803

  2. OUTLINE • Abstract • Introduction • Process overview • Template assisted self assembly • Results and discussion • Transfer of nanoparticles • LSPR characteristics of assembled Nanoparticle patterns • Conclusion

  3. Abstract • Pattern formation • Dot and line pattern • Assembled particle pattern transfer • Localized Surface Plasmon Resonance (LSPR)

  4. Introduction • Characteristics of nanoparticles • Conventional nanopatterning techniques • Advantages of proposed method • 60-nm diameter gold nanoparticles

  5. PROCESS OVERVIEW 1) Self-assembly step 2)Transfer step

  6. Template assisted self assembly • Mechanism of TASA • Aqueous particle dispersion • Capillary force

  7. Result and discussion • Effect of cross sectional shape • Relation between yield and concentration • The self-assembly yield is defined as the ratio of the total dot-patterned area to the properly assembled area.

  8. SEM images of each cross-section before resist removal. Shape A, B and Shape C were fabricated by SF6 and CF4 dry etching, respectively.

  9. Relation between a cross-sectional profile of a template pattern and a yield of self-assembly (the concentration of particle dispersion: 0.002 wt%) Relation between concentration of particle dispersion and a yield of self-assembly.

  10. Capillary force

  11. Template transfer process • SiO2/Si substrate with assembled particles • Uncured PDMS was poured onto the template • (base compound : curing agent = 10:1) • (3) Degassing for 30 min • (4) Curing PDMS (60 ℃ for 4 hr) • (5) Peel off PDMS

  12. Au self-assemble on the template Transferred pattern on the PDMS (> 90% successful)

  13. LSPR principle • Noble metal nanoparticles exhibit a strong UV-vis absorption band that is not present in the spectrum of the bulk metal. • This absorption band results when the incident photon frequency is resonant with the collective oscillation of the conduction electrons and is known as the localized surface plasmon resonance (LSPR). • E(λ) = extinction (viz., sum of absorption and scattering) • NA = area density of nanoparticles • a = radius of the metallic nanosphere • em=dielectric constantof the medium surrounding the metallicnanosphere • λ =wavelength of the absorbingradiation • εi = imaginary portion of the metallic nanoparticle's dielectric function • εr = real portion of the metallic nanoparticle's dielectric function • χ =2 for a sphere(aspect ratio of the nanoparticle)

  14. LSPR characteristics • These mechanisms are: • resonant Rayleigh scattering from nanoparticle labels in a manner analogous to fluorescent dye labels • nanoparticleaggregation • charge-transfer interactions atnanoparticle surfaces • local refractive index changes • This approach has many advantages including: • a simple fabrication technique that can be performed in most labs • real-time biomolecule detection using UV-vis spectroscopy • a chip-based design that allows for multiplexed analysis

  15. LSPR applications • Sensor • adsorption of small molecules • ligand-receptor binding • protein adsorption on self-assembled monolayers • antibody-antigen binding • DNA and RNA hybridization • protein-DNA interactions

  16. LSPR scattering spectrum Dot pattern aperture Schematic of dark-field microscope line pattern

  17. Dark-field microscope

  18. Scattering spectrums of line patterns w/o polarization line pattern w/o polarization

  19. Spectrum peak vs. refractive index p-polarized light s-polarized light Polarizing cube beamsplitter Non-polarized light non-polarized light p-polarized light s-polarized light

  20. Conclusions • Self-assembly nanoparticle pattern formation method can be realized more than 90% onto 200 x 200 dots. • Dot and line patterns of gold nanoparticles in diameter of 60 nm were transferred on a flexible PDMS substrate. • LSPR sensitivity will be possible by controlling patterns of the assembled nanoparticles. • In the future, it is expected that this method will realize novel MEMS/NEMS devices with nanoparticles patterns on various 3D microstructures made of various materials via a carrier substrate.

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