Study of plasmonic nano-arrays for the development of cost-effective SERS substrate
Due to its excellent signal uniformity and reproducibility, well-ordered plasmonic nano-arrays demonstrate great potential as practical SERS probe for real-time in-situ analysis of molecules. A basic study of SERS mechanism was carried out to elucidate relevant factors that can affect SERS enhanceme...
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| Format: | Thesis |
| Language: | English |
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2018
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| Online Access: | http://hdl.handle.net/10356/75742 |
| _version_ | 1826128862634835968 |
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| author | Lim, Lu Kai |
| author2 | Ng Beng Koon |
| author_facet | Ng Beng Koon Lim, Lu Kai |
| author_sort | Lim, Lu Kai |
| collection | NTU |
| description | Due to its excellent signal uniformity and reproducibility, well-ordered plasmonic nano-arrays demonstrate great potential as practical SERS probe for real-time in-situ analysis of molecules. A basic study of SERS mechanism was carried out to elucidate relevant factors that can affect SERS enhancement. The results revealed that the rarely discussed scattering cross-section can have substantial influence on SERS enhancement and should be considered for a complete understanding and optimization of the performance of SERS substrates. Two commonly used metallization techniques, DC sputtering and electron-beam (E-beam) evaporation, was investigated to quantify their effect on SERS performance. It was found that the E-beam evaporation technique produces inherently roughened gold film which serve as additional EM hotspots favourable for SERS. A hybrid metal deposition approach to exploit the advantages of both the sputtering and E-beam technique is proposed and verified. Two well-ordered and cost-effective SERS substrates were proposed and investigated. The first is a Au-SiO2 nano-pillar substrate fabricated by performing an additional plasma enhanced chemical vapour deposition of SiO2 on nanosphere-lithorgraphy fabricated Si pillars to tune the plasmonic resonance of the nano-structures. The optimized Au-SiO2 nano-pillar exhibits comparable SERS performance as the well-established gold-film-over-nanosphere substrate and has the added advantage of better stability and reusability due to its inherently rigid structure. The second SERS substrate developed in this work comprises non-lithographic anodized aluminium oxide (AAO)-based nano-fibres (ANF) that are fabricated by optimizing the second anodization and incorporating an additional chemical wet-etching step. The optimized ANF substrate exhibits better sensitivity, signal-to-noise ratio, signal uniformity and stability than those of conventional substrates. The fabrication process of the ANF SERS substrate is also highly reproducible and scalable. Label-free detection of two DNA and RNA nucleobases are also demonstrated with the ANF SERS substrate. |
| first_indexed | 2024-10-01T07:31:27Z |
| format | Thesis |
| id | ntu-10356/75742 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2024-10-01T07:31:27Z |
| publishDate | 2018 |
| record_format | dspace |
| spelling | ntu-10356/757422023-07-04T17:31:22Z Study of plasmonic nano-arrays for the development of cost-effective SERS substrate Lim, Lu Kai Ng Beng Koon School of Electrical and Electronic Engineering DRNTU::Engineering::Nanotechnology Due to its excellent signal uniformity and reproducibility, well-ordered plasmonic nano-arrays demonstrate great potential as practical SERS probe for real-time in-situ analysis of molecules. A basic study of SERS mechanism was carried out to elucidate relevant factors that can affect SERS enhancement. The results revealed that the rarely discussed scattering cross-section can have substantial influence on SERS enhancement and should be considered for a complete understanding and optimization of the performance of SERS substrates. Two commonly used metallization techniques, DC sputtering and electron-beam (E-beam) evaporation, was investigated to quantify their effect on SERS performance. It was found that the E-beam evaporation technique produces inherently roughened gold film which serve as additional EM hotspots favourable for SERS. A hybrid metal deposition approach to exploit the advantages of both the sputtering and E-beam technique is proposed and verified. Two well-ordered and cost-effective SERS substrates were proposed and investigated. The first is a Au-SiO2 nano-pillar substrate fabricated by performing an additional plasma enhanced chemical vapour deposition of SiO2 on nanosphere-lithorgraphy fabricated Si pillars to tune the plasmonic resonance of the nano-structures. The optimized Au-SiO2 nano-pillar exhibits comparable SERS performance as the well-established gold-film-over-nanosphere substrate and has the added advantage of better stability and reusability due to its inherently rigid structure. The second SERS substrate developed in this work comprises non-lithographic anodized aluminium oxide (AAO)-based nano-fibres (ANF) that are fabricated by optimizing the second anodization and incorporating an additional chemical wet-etching step. The optimized ANF substrate exhibits better sensitivity, signal-to-noise ratio, signal uniformity and stability than those of conventional substrates. The fabrication process of the ANF SERS substrate is also highly reproducible and scalable. Label-free detection of two DNA and RNA nucleobases are also demonstrated with the ANF SERS substrate. Doctor of Philosophy (EEE) 2018-06-13T06:04:19Z 2018-06-13T06:04:19Z 2018 Thesis Lim, L. K. (2018). Study of plasmonic nano-arrays for the development of cost-effective SERS substrate. Doctoral thesis, Nanyang Technological University, Singapore. http://hdl.handle.net/10356/75742 10.32657/10356/75742 en 151 p. application/pdf |
| spellingShingle | DRNTU::Engineering::Nanotechnology Lim, Lu Kai Study of plasmonic nano-arrays for the development of cost-effective SERS substrate |
| title | Study of plasmonic nano-arrays for the development of cost-effective SERS substrate |
| title_full | Study of plasmonic nano-arrays for the development of cost-effective SERS substrate |
| title_fullStr | Study of plasmonic nano-arrays for the development of cost-effective SERS substrate |
| title_full_unstemmed | Study of plasmonic nano-arrays for the development of cost-effective SERS substrate |
| title_short | Study of plasmonic nano-arrays for the development of cost-effective SERS substrate |
| title_sort | study of plasmonic nano arrays for the development of cost effective sers substrate |
| topic | DRNTU::Engineering::Nanotechnology |
| url | http://hdl.handle.net/10356/75742 |
| work_keys_str_mv | AT limlukai studyofplasmonicnanoarraysforthedevelopmentofcosteffectiveserssubstrate |