표면 증강 라만 산란 효과 유도에 응용을 위한 홀로그래픽 나노구조의 제조에 관한 연구

학위논문(박사) - 한국과학기술원 : 생명화학공학과, 2014.2, [ xi, 117 p. ]Holographic lithography (HL) has been developed to produce a large variety of defect-free three-dimensional (3D) periodic nanostructures over large areas. To fabricate such nanostructures, the optical interference among multiple coherent beams is transferred into photoresist. However, conventional multi-beam HL requires complex optical setup composed of beam splitters, mirrors, and polarizers with elaborate alignment. To overcome such shortcomings, prism is employed for laser beam splitting and recombination; this prism HL provides simple and rapid method to create periodic nanostructures.Meanwhile, surface enhanced Raman scattering (SERS) has been emerged as one of the powerful strategies for fast detection of characteristic “fingerprint” signatures of numerous chemical and biological molecules. The SERS is derived from strong electromagnetic (EM) field enhancements at the surface of metallic nanoparticles or nanoarrays by the plasmonic resonance. To fabricate SERS-active metallic nanostructures, a variety of techniques have been developed, which enable to design the optimal geometric features for sensing applications. However, simultaneous achievement of high reproducibility and large-scale sample homogeneity while maintaining high sensitivity still remains an important challenge.Here, I describe the multipurpose prism HL-featured 3D periodic nanostructures which provide uniform and reproducible 2D/3D SERS substrates. In Chapter 1, I briefly introduce the principle of prism HL technique and SERS phenomena. One lesson from Chapter 1 is metallic structures which possess nano-sized gaps or sharp corners provide high Raman signal enhancement; this is contributed from the locally-enhanced magnitude of EM fields at those gaps or corners. To engineer the nanogaps in metallic nanostructure, I have developed novel method for fabricating uniformly-ordered plasmonic arrays with controllable nanogaps. In Chapter 2, I report the method and unique optical properties of th...한국과학기술원 : 생명화학공학과

Hexagonally Ordered Arrays of Elliptical Silicon Nanowires Featured by Holographic Lithography for SERS Applications

Surface-enhanced Raman scattering (SERS)—of which the enhancement depends on the type, size, roughness and shape of metal nanoparticles and the distance between them—is a powerful strategy for sensing applications. Here, a novel, highly uniform and tunable hybrid SERS substrate has been achieved via prism holographic lithography (HL), ion-milling, catalytic wet-etching process, and electron-beam evaporation. The triply-split Au hole arrays, which can be fabricated using HL-featured structures as milling masks, act as the silicon (Si) wafer etching catalyst in a reaction solution to fabricate well-ordered silicon nanowire (SiNW) arrays. After removing the polymeric mask and metal thin film, the Au thick film is highly-anisotropically deposited on the hexagonally ordered triangularly coordinated elliptical SiNW arrays. This hybrid substrate shows tunable SERS activities according to the catalytic wet etching times causing different vertical gap distances. Moreover, highly intensified SERS signals can be achieved deriving from lateral interparticle coupling compared to the circular SiNW arrays with the good homogeneity

Photonic Crystal Microparticles Fabricated by Interference Lithography for Surface-Enhanced Raman Scattering

We report the novel method for fabricating surface-enhanced Raman scattering (SERS) particle based on silver nanoparticles (NPs) decorated photonic crystal microparticles with internal woodpile structures by combining the hot-embossing process and prism holographic lithography (HL). First, microarrays of disk shape are obtained by hot-embossing process using PDMS elastomeric mold. Prism HL induces internal woodpile structure with various reflectance peak positions by controlling exposure time during the process. Finally, we can obtain free-floating photonic crystal microparticles after removing residual layer of microarrays and releasing from the substrates by reactive ion etching and pre-coated sacrificial layer respectively. And silver NPs are decorated on these free-floating HL microparticles by electro-less deposition. The resulting microparticles exhibit highly enhanced sensitivity of SERS because of the 3D porous structure

Fabrication Method of Microcapsules Using Anisotropic Swelling of Bilayer Hydrogel Microparticles

본 발명은 이중층을 갖는 하이드로젤(hydrogel) 미세입자로 구성된 미세수송체에 관한 것이다. 보다 상세하게는 비등방성 부품(swelling)에 의해 평면형의 하이드로젤 미세입자가 삼차원적인 닫힌계를 갖는 미세캡슐로 변형되어 목표물질의 감금, 수송, 방출이 가능한 이중층을 갖는 하이드로젤 미세입자로 구성된 미세수송체에 관한 것이다