Manipulation of Fluid Convection by Surface Lattice Resonance

Abstract

reported that the fluid flow control can be achieved at the scale of optical wavelengths, which led to the development of applications in biochemical assaybased microfluidics and nanophysics. [1,2] However, the diffraction limit of light restricts optofluidic applications at the molecular level. Additionally, high-intensity optical pulses cause undesirable photo bleaching or photoinduced damage to biomedical molecules in an optofluidic system. Surface plasmons are the collective excitation of free electrons in metals, allowing breaking the diffraction limit for the localization of light into subwavelength dimensions, enabling strong field enhancements and light-matter interactions. [3] In particular, photothermal effects in plasmonic nanoparticles (NPs) can be enhanced via enhanced light absorption, generating heat via nonradiative decay channel. [4][5][6][7][8] One can thereby manipulate fluid flows; and control suspended objects at the subwavelength scale by using plasmonics. Localized surface plasmon (LSP) and surface plasmon polariton (SPP) have been developed to manipulate fluid convection, living cells, DNA, and proteins. [9][10][11][12][13] For example, the photothermal effect caused by LSPs of Au NPs' array in optofluidics was investigated by Miao et al. [12] Such LSP energy-induced optofluidic mixing could obtain high optical-to-thermal energy conversion efficiency. Min et al. showed the optofluidic trapping and manipulation of metallic particles by the excitation of SPP on a thin layer of the gold film. [13] Such a highly confined SPP field, strongly interacting with metallic particles, forms gradient and scattering forces required for the electromagnetic trapping act. Plasmonics can also find its application in high-sensitive biomolecular binding events. For instance, plasmonic nanohole arrays were used as substrates for label-free detection. [14] However, the practical application of these LSP-or SPP-based metasurfaces is limited in plasmonic optofluidics due to the dephasing and broad bandwidth. The high-quality (Q)-factor of the plasmonic surface lattice resonance (SLR) can alleviate the problem. The interference between the LSP and the diffractive behavior of the periodic metallic nanostructures characterizes the SLR. The SLRs are well known for overcoming the damping of LSPs and minimizing scattering losses from gratings, resulting in very narrow bandwidth. Considering that SLRs for noble metal lattices have very high Q-factors with respect to LSPs, the plasmon dephasing time is several orders of magnitude longer for SLRs, [15] allowing long-life light trapping.The capability of plasmonic metasurfaces (PMs) under illumination to generate heat and induce fluid convection is a promising building approach for optofluidic applications. However, the low quality (Q)-factor in PMs introduced into optofluidic applications remains a challenging problem. In this paper, a PM optofluidic platform based on surface lattice resonance (SLR) with a high Q-factor is proposed. Numerical results demonstrate that SLR-...

Engineering Fano‐Resonant Hybrid Metastructures with Ultra‐High Sensing Performances

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Thermal Vertical Emitter of Ultra‐High Directionality Achieved Through Nonreciprocal Magneto‐Optical Lattice Resonances

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