Aluminum Metasurface with Hybrid Multipolar Plasmons for 1000-Fold Broadband Visible Fluorescence Enhancement and Multiplexed Biosensing

Abstract

Aluminum (Al)-based nanoantennae traditionally suffer from weak plasmonic performance in the visible range, necessitating the application of more expensive noble metal substrates for rapidly expanding biosensing opportunities. We introduce a metasurface comprising Al nanoantennae of nanodisks-in-cavities that generate hybrid multipolar lossless plasmonic modes to strongly enhance local electromagnetic fields and increase the coupled emitter's local density of states throughout the visible regime. This results in highly efficient electromagnetic field confinement in visible wavelengths by these nanoantennae favoring real-world plasmonic applications of Al over other noble metal. Additionally, we demonstrate spontaneous localization and concentration of target molecules at metasurface hotspots, leading to further improved on-chip detection sensitivity and a broadband fluorescence-enhancement factor above 1000 for visible wavelengths with respect to glass chips commonly used in bioassays. Using the metasurface and a multiplexing technique involving three visible wavelengths, we successfully detected three biomarkers, insulin, vascular endothelial growth factor, and thrombin relevant to diabetes, ocular and cardiovascular diseases, respectively, in a single 10-L droplet containing only 1 fmol of each biomarker.

Metasurfaces for biomedical applications: imaging and sensing from a nanophotonics perspective

“…Hence we have made the scope of this review paper to metasurface biosensing at the molecular and cellular levels with a focus on results that have appeared after the first introduction of the metasurface concept [8]. This section covers metasurface biosensors developed and applied for the targeted detection of antibodies and proteins [127][128][129][130][131][132][133][134][135][136], DNAs [138][139][140][141][142][143], cells [141][142][143][144][145], and cancer biomarkers [146][147][148][149]. Table 1 summarizes the performance of different metasurface Box 2 Performance factors of metasurface biosensors…”

“…Aluminum normally provides weak plasmonic response due to the relatively low electron density compared to noble metals. However, Siddique et al [133] recently presented a metasurface structure comprising aluminum-based nanodisks-in-cavities array which could achieve 1000-fold fluorescence enhancement in the visible wavelength range. This designed structure generated hybrid multipolar lossless plasmonic modes, which enabled strong electromagnetic field confinement.…”

Butterfly wing architectures inspire sensor and energy applications

“…However, existing traditional sensors exhibit limitations that impede their efficiency and accuracy. These include, sophisticated microfabrication methods, narrow test ranges, low spatial resolution, low selectivity and difficulty in controlling the microstructures [ 92 ]. Therefore, the development of sensors that overcome these limitations is of great importance.…”

Progress in wafer bonding technology towards MEMS, high-power electronics, optoelectronics, and optofluidics

“…Sensing technologies are important for personal healthcare, [106][107][108][109] studies of biochemical reaction, [110,111] and environment monitoring. [112][113][114][115][116][117][118][119][120][121][122][123][124] A single technique is not enough to meet the multiple requirements of detection analysis.…”