The perspectives of broadband metasurfaces and photo-electric tweezer applications

Abstract

With strong demands of real-time monitoring of biomolecules or environmental pollutants, overcoming technical hurdles on control and detection of freely diffusive nanoscale objects become a question of issue to solve in a variety of research fields. Most existing optical techniques inevitably require labeling to the target material, which sometimes denature the measuring biomaterials. For highly efficient real-time monitoring without complicated pretreatment or labeling, many successes in development of label-free or non-destructive detection techniques via increased sensitivity were accomplished by the additional structures. Metasurface-based two-dimensional photonic/electric devices have recently represented extraordinary performances in both manipulation and sensing for various small particles and biochemical species, repeatedly overcoming the limit of detection achieved right before. In parallel, various metasurface-based devices were also introduced promoting transportation of targets into optical hotspot sites, overcoming diffusion limits. We noted this point, therefore, reviewed two major research fields such as metasurface-assisted material sensing and transportation technologies that have contributed to present prospective sensing technologies, then showed perspective views on how great synergy can be created when two technologies are cleverly integrated. Recently, a trend of conceptual merging of optical detection and transporting schemes beyond both diffraction limit and diffusion limit leads to a creation of exceptional performance in molecular detections. In this review, the trends of the latest technologies accomplishing this purpose by hybridization of various composite materials and functional metasurfaces will be introduced.

Real-Time Underwater Nanoplastic Detection beyond the Diffusion Limit and Low Raman Scattering Cross-Section via Electro-Photonic Tweezers

“…In the absence of these external forces for target migration, the accumulation process is significantly hindered by the diffusion limit , (left; Figure d). For a solution containing the target analytes (initial concentration of c 0 ), the time ( t ) required to accumulate n number of analytes (irreversible adsorption) on a circular disk-shaped detection region (radius of a ) is theoretically given as t ( n ) = n /4 DN A c 0 a , where D and N A represent the diffusion constant of analytes and Avogadro’s number.…”

“…Therefore, systematic measurement and analysis of Raman signals, precise measurement of material properties of target analytes, and integration with microfluidic screening systems remain our future work to realize practical biosensing platforms with target-selective separation. Furthermore, as our platform ensures high degrees of flexibility on device geometry, our device configuration can be integrated into metasurfaces to facilitate the development of optical nanosensors at various frequency regimes. , Consequently, our strategies, which adopt electrical tweezing and 3D reconfigurable SERS nanoparticles, will present considerable implications in various fields, from nanophotonic sensors to biosensing.…”

“…13 However, the effective in situ monitoring of sub-100-nm nanoplastics directly from the ecosystem is primarily limited by two factors: (i) diffusion limit and (ii) low Raman scattering cross-section. The diffusion limit issue 14,15 intrinsic nature of nanoplastics caused by their extremely low concentration in the ecosystem (approximately 20 μg•L −1 in seawater 16 ). 17 The Raman analytic procedure requires target molecules to be located within a micrometer-scaled laser spot as modern Raman spectroscopy relies on the inelastic Raman scattering of photons from laser sources.…”

Dynamic Trapping and Manipulation of Self-Assembled Ag Nanoplates as Efficient Plasmonic Tweezers

“…To increase metal heat dissipation, the metal nanocavity-based structures could improve the efficiency of heat dissipation, and the concave structures in the metal film surrounded by large heat sinks can dissipate heat rapidly. , Additionally, the LSPRs and optical force can be tuned by controlling the geometry and arrangement of the plasmonic nanostructures, − allowing for the creation of hot spots at a desired position. The enhanced trapping force and precise control offered by plasmonic tweezers have expanded the capabilities of OTs and have become a valuable tool in the fields of biological sensing, − biomedicine, , label-free single bioparticle imaging, − and single-atom manipulation. − …”

Diffractive optical elements 75 years on: from micro-optics to metasurfaces

“…Metasurfaces, 2D planar structures with subwavelength thickness, represent the 2D counterparts to metamaterials and have garnered significant attention owing to their straightforward fabrication processes. They are heralded as the next-generation flat-optics devices, boasting a multitude of functions [3–32] . One of their most crucial attributes lies in their capacity to provide diverse degrees of freedom for the precise modulation of light beams.…”