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Nanoplasmonic sensing relies on enhanced electromagnetic fields at the vicinity of nanostructured metal surface to detect molecules at ultra-low concentrations. The EM enhancements are strongly pronounced at junctions between adjacent nanostructures resulting in gap hot-spots. EM enhancements at these hot-spots increase non-linearly as a function of gap distances down to sub-10 regime. Analyte present at these gaps can leverage these EM enhancements, resulting in ultra-high sensitivity in detection. However, such confining gaps affect the ability of large analytes such as biomolecules to enter and thereby leverage EM fields within the gaps. This presents spatial needs to enhance EM fields at odds with those for accommodating biomolecular interactions. This thesis demonstrates the rational design of array configurations that allows the EM hotspots to be better leveraged by the reporter of biomolecular binding event. The thesis uses molecular self-assembly based approach to fabricate reproducible plasmonic nanoarrays on full wafers. Multiple parameters are considered including the dimension, shape, and density of hotspots, surface functionalization, and the choice of substrates, to demonstrate quantitative detection of molecules down to picomolar concentrations.; La détection nanoplasmonique repose sur des champs électromagnétiques exaltés à proximité de la surface des métaux nanostructurés pour détecter les molécules à des concentrations ultra-faibles. Les exaltations de champ sont fortement prononcées aux jonctions entre les nanostructures adjacentes, ce qui entraîne des points chauds. Les exaltations de champ en ces points chauds augmentent de façon non linéaire en fonction des distances jusqu’au régime inférieur à 10nm. Les analytes présents à ces lacunes peuvent tirer parti de ces exaltations de champ, résultant en une sensibilité ultra-élevée dans la détection. Toutefois, ces lacunes de champ confiné affectent la capacité des grands analytes tels que les biomolécules d’entrer et de tirer ainsi parti des champs EM dans les lacunes. Cela présente des besoins spatiaux pour exalter les champs em en contradiction avec ceux pour accueillir les interactions biomoléculaires. Cette thèse démontre la conception rationnelle des configurations de réseaux qui permet aux hotspots EM d’être mieux exploités par le témoin de l’événement de liaison biomoléculaire. La thèse utilise l’approche moléculaire basée sur l’auto-assemblage pour fabriquer des nanoréseaux plasmoniques reproductibles sur des plaquettes complètes. Plusieurs paramètres sont envisagés, y compris la dimension, la forme et la densité des points chauds, la fonctionnalisation de surface, et le choix des substrats, pour démontrer la détection quantitative des molécules jusqu’aux concentrations picomolaires.

International audience

International audience

International audience

International audience

Recent developments in nanoplasmonic sensors promise highly sensitive detection of chemical and biomolecular analytes with quick response times, affordable costs, and miniaturized device footprints. These include plasmonic sensors that transduce analyte-dependent changes to localized refractive index, vibrational Raman signatures, or fluorescence intensities at the sensor interface. One of the key challenges, however, remains in producing such sensors reliably, at low cost, using manufacturing compatible techniques. In this chapter, we demonstrate an approach based on molecular self-assembly to deliver wafer-level fabrication of nanoplasmonic interfaces, with spatial resolutions down to a few nanometers, assuring high quality and low costs. The approach permits systematic variation to different geometric variables independent of each other, allowing the significant opportunity for the rational design of nanoplasmonic sensors. The ability to detect small molecules by SERS-based plasmonic sensing is compared across different types of metal nanostructures including arrays of nanoparticle clusters, nanopillars, and nanorod and nanodiscs of gold.