Surface Functionalization and Texturing of Optical Metasurfaces for Sensing Applications

Abstract

Optical metasurfaces are planar metamaterials that can mediate highly precise light−matter interactions. Because of their unique optical properties, both plasmonic and dielectric metasurfaces have found common use in sensing applications, enabling label-free, nondestructive, and miniaturized sensors with ultralow limits of detection. However, because bare metasurfaces inherently lack target specificity, their applications have driven the development of surface modification techniques that provide selectivity. Both chemical functionalization and physical texturing methodologies can modify and enhance metasurface properties by selectively capturing analytes at the surface and altering the transduction of light− matter interactions into optical signals. This review summarizes recent advances in materialspecific surface functionalization and texturing as applied to representative optical metasurfaces. We also present an overview of the underlying chemistry driving functionalization and texturing processes, including detailed directions for their broad implementation. Overall, this review provides a concise and centralized guide for the modification of metasurfaces with a focus toward sensing applications.

Probing and Manipulating Noncovalent Interactions in Functional Polymeric Systems

“…Surface modification is a widely used strategy to endow substrates with responsiveness and/or functionalities, which can be achieved via both chemical and physical approaches. Covalent functionalization commonly involves thiol chemistry (Au-SH), click chemistry (alkyne coating followed by azide–alkyne reaction), polymer brushes (initiator immobilization followed by polymerization of monomers), anchor molecules (silane, catechol, phosphate) followed by a polymer graft, 1-ethyl-3-(3-(dimethylamino)­propyl)­carbodiimide/ N -hydroxysuccinimide (EDC/NHS) linker, and so on. ,− Physical approaches, from the perspective of surface morphology, usually include roughening (plasma etching and mechanical roughening) and patterning (lithography, direct-writing, 3D patterning), which would not be discussed in details in this review . The following subsections would emphasize the approaches toward surface functionalization based on noncovalent molecular interactions, among which layer-by-layer assembly is first elucidated from the aspects of sensing, drug delivery, functional coatings, fuel cells, catalysis, packaging, water treatment, and so on.…”

Metasurface-Incorporated Optofluidic Refractive Index Sensing for Identification of Liquid Chemicals through Vision Intelligence

“…Metasurfaces alter the optical characteristics of a light beam, such as phase, intensity, polarization, and shape, exhibiting unprecedented electromagnetic domain properties. − All-dielectric metasurface-based optical devices have been used as highly sensitive optical platforms for the reliable and rapid detection of biomolecules. − They exploited the resonant wavelength shift of these devices, which were kept in close contact with a biomolecule, for their strong light-matter interaction at subwavelength scales. , In conformance with a lab-on-a-chip and micro total analysis system, ,− metasurface-integrated optofluidic devices help develop a miniaturized biosensing system featuring an expedited real-time chemical analysis . Recently reported metasurface-based biosensing approaches leveraged the hyperspectral multipixel imaging of the spectral resonance shift in the meta-atoms of an all-dielectric device with a high-Q-factor resonator and the analysis of the captured images using complex computation techniques; , this has initiated the development of compact spectrometer-free biosensors.…”

Recent Development in Metasurfaces: A Focus on Sensing Applications

“…In the literature, several interesting reviews on MSs can be found which are highly recommended to readers. For instance, in [ 51 ], the most recent developments in material-specific surface functionalization and texturing are discussed as they are applied to sample optical MSs. Detailed instructions for the widespread implementation of this approach are also provided, along with an understanding of the underlying chemistry that powers functionalization and texturing operations.…”