Oral Presentation 26th ACMM “2020 Visions in Microscopy”

Nanocharacterisation of Gold-based Plasmonic Sensor for Performance Optimisation (#121)

Mansoor Ali Khan 1 , Ying Zhu 1 , Yin Yao 2 , Peter J Reece 3
  1. UNSW Medicine, St. George and Sutherland Clinical School, University of New South Wales, Sydney, NSW, Australia
  2. Electron Microscope Unit , University of New South Wales, Sydney, NSW, Australia
  3. Physics, University of New South Wales, Sydney, NSW, Australia

Gold-based thin-film smart plasmonic sensors are promising tool for today’s on-chip detection of biomolecular binding, drug discovery, cancer detection and other clinical diagnosis1-3. In this work, gold (Au) as a surface plasmonic film of biophotonic sensor has been systematically investigated by correlating scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and atomic force microscopy (AFM) techniques. In the context of high-surface sensitivity, two critical aspects have been scrutinized on the nanoscale: (1) surface topography, and (2) grain morphology of the Au-metallic film. For comparative analysis, electron-beam and thermal methods have been applied for Au deposition. Using advance SEM/EBSD and AFM tools, we found that the surface morphology, which includes grain size (grain morphology) and surface roughness (surface topography) of the Au-layer impacts the optical properties, quality factor and sensitivity of the plasmonic nanohole array sensor. Meanwhile, the grain morphology and topographical analyses revealed the nanomorphology of the Au film, where a nanograin size of ∼30-50 nm with special nano-twinned boundaries and an extremely smooth surface of sub-nm are required for better surface plasmonic resonance.

Furthermore, based on these electron and atomic force microscopy results, suggestions on sensitivity optimization are given to improve the performance of standard Au-based biophotonic sensors. Our findings via powerful microscopy tools enable fresh and deep understanding of performance−microstructure correlation of plasmonic sensor on the nanoscale, thus providing guidance to design and fabricate high-performance sensor devices for biomedical applications.

  1. (1) Prasad, A.; Choi, J.; Jia, Z.; Park, S.; Gartia, M. R. Nanohole Array Plasmonic Biosensors: Emerging Point-of-Care Applications. Biosensors and Bioelectronics 2019, 130, 185–203. https://doi.org/10.1016/j.bios.2019.01.037. (2) Im, H.; Shao, H.; Park, Y. I.; Peterson, V. M.; Castro, C. M.; Weissleder, R.; Lee, H. Label-Free Detection and Molecular Profiling of Exosomes with a Nano-Plasmonic Sensor. Nature Biotechnology 2014, 32 (5), 490–495. https://doi.org/10.1038/nbt.2886. (3) Lopez, G. A.; Estevez, M.-C.; Soler, M.; Lechuga, L. M. Recent Advances in Nanoplasmonic Biosensors: Applications and Lab-on-a-Chip Integration. Nanophotonics 2017, 6 (1), 123–136. https://doi.org/10.1515/nanoph-2016-0101.