Dielectric metasurfaces for next-generation optical biosensing: a comparison with plasmonic sensing

Abstract

In the past decades, nanophotonic biosensors have been extended from the extensively studied plasmonic platforms to dielectric metasurfaces. Instead of plasmonic resonance, dielectric metasurfaces are based on Mie resonance, which provide comparable sensitivity with superior resonance bandwidth, Q factor, and figure-of-merit. Although the plasmonic photothermal effect is beneficial in many biomedical applications, it is a fundamental limitation for biosensing. Dielectric metasurfaces solve the Ohmic loss and heating problems, providing better repeatability, stability, and bio-compatibility. We review the high-Q resonances based on various physical phenomena tailored by meta-atom geometric designs, and compare dielectric and plasmonic metasurfaces in refractometric, surface-enhanced, and chirality sensing for various biomedical and diagnostic applications. Departing from conventional spectral shift measurement using spectrometers, imaging-based and spectrometer-less biosensing are highlighted, including single-wavelength refractometric barcoding, surface-enhanced molecular fingerprinting, and integrated visual reporting. These unique modalities enabled by dielectric metasurfaces point to two important research directions. On the one hand, hyperspectral imaging provides massive information for smart data processing, which not only achieve better biomolecular sensing performance than conventional ensemble averaging, but also enable real-time monitoring of cellular or microbial behaviour in physiological conditions. On the other hand, a single metasurface can integrate both functions of sensing and optical output engineering, using single-wavelength or broadband light sources, which provides simple, fast, compact and cost-effective solutions. Finally, we provide perspectives in future development on metasurface materials, configurations, nanofabrication, surface modification and system integration, towards next-generation optical biosensing for ultra-sensitive, portable/wearable, lab-on-a-chip, point-of-care, multiplexed and scalable applications.

Review of metasurface structures for biomedical sensing platforms: Principles, applications, fabrication, and future perspectives

“…In recent years, metasurface biosensors have also expanded to include dielectric metasurfaces based on Mie resonance (resonances of spherical/spheroidal dielectric particles), Fano resonance (coupling between two/multiple resonance modes), etc. These provide comparable sensitivity with superior resonance bandwidth, enhanced quality (Q) factors, better field confinement, and the potential to address the ohmic loss and heating issues associated with current plasmonic sensors, thereby ensuring improved stability and biocompatibility [11,12].…”

Dielectric terahertz metasurface governed by symmetry-protected BIC for ultrasensitive sensing

“…Due to the intrinsic material loss, the Q factor of metallic metasurface is generally lower than that of dielectric metasurface. But dielectric metasurface generally suffers from low sensitivity on account of low spatial distributions of enhanced fields in the sensing analyte [54,55]. The designed metasurface in this work shows an intense electromagnetic field around the pillars so that the QBIC resonance can be more sensitive to the surrounding analyte.…”

Off-axis bifocal metalens for displacement measurement

“…They clarified that transmitted light and reflected light can propagate in any direction in their respective half space, and the propagation direction depends on the direction of the metasurface phase gradient, the numerical magnitude and the refractive index of the surrounding medium. Metasurfaces have been widely used in wavefront engineering [3][4][5][6], focusing or imaging elements [7][8][9][10][11], beam shaping [12], vortex beam generation [13][14][15][16], holographic technology [17][18][19], biosensing [20], electromagnetic concealment [21], achromatic focusing [22], electromagnetic wave modulation [23] and nonlinear interactions [24,25] have been applied in 3D imaging [26], Cellular-resolution optical coherence tomography [27], holographic imaging [28][29][30][31], optical cryptography [32,33] and wireless power transfer (WPT) system [34][35][36]. For example, researchers achieved optical information multiplexing by a designed multifocal metalens using of nonlinear coding Pancharatnam-Berry phase metasurface [37].…”