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Directional droplet manipulation is very crucial in microfluidics, intelligent liquid management, etc. However, excessive liquid pressure tends to destroy the solid–gas–liquid (SAL) composite interface, creating a highly adhesive surface, which is not conducive to liquid transport. Herein, we propose a strategy to enhance the surface durability, in which the surface cannot withstand liquid pressure only by “blocking” but must instead guide liquid transport for “decompression”. Learning from the water resistance of water strider legs and the drag reduction of shark skin, we present a continuous integrated system to obtain an ultrastable super-hydrophobic surface with a highly ordered scaly structure via a liquid flow-induced alignment method for lossless unidirectional liquid transport. The nonwetting scaly structure can both buffer liquid pressure and drive droplet motion to further reduce the vertical pressure of the liquid. Moreover, droplets can be manipulated unidirectionally using a voice. This work could aid in manufacturing scalable anisotropic micro-nanostructure surfaces, which inspires efforts in realizing lossless continuous liquid control on demand and related microfluidic applications.

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Surface-enhanced Raman scattering (SERS) is of great importance for the sensitive, rapid, and repeatable detection of target analytes. The electromagnetic enhancement has a major contribution to the signal enhancement in SERS which is critically dependent on the micro-/nanomorphology of noble metal (e.g., Au and Ag) film substrates. Herein, Ag nanocubes/polyelectrolyte/Au (Ag/PE/Au) sandwich-structured film is fabricated by the layer-by-layer deposition and then utilized as an efficient SERS substrate by the coupling of localized surface plasmons (LSPs) and surface plasmon polaritons (SPPs) resonances while the electromagnetic field enhancement is confined within the PE gap layer which is sandwiched between Ag nanocubes and Au film. With rhodamine 6G and crystal violet as the probe molecules, the Ag/PE/Au sandwichstructured film demonstrates highly sensitive SERS signals, which is further supported by the theoretical simulations as well. This work indicates that the Ag/ PE/Au sandwich-structured film can be employed as a reliable SERS substrate for sensitive molecular sensing applications.

A metallic nanoparticle positioned over a metal film offers enormous advantages as a highly controllable system relevant for probing field-enhancement and designing controlled-emissivity surfaces for thermophotovoltaic devices. The film-coupled silver (Ag) nanoparticle is of particular interest due to the formation of waveguide cavity-like modes between the NPs and film. The ability of individual nanopolyhedron (NP) patch antennas, consisting of Ag NP separated from gold (Au) film by a dielectric spacer layer spacer, to act as efficient and tunable absorption elements is demonstrated. The size and shape of the gap between the nanoparticle and film can be precisely controlled using relatively simple, bottom-up fabrication approaches. We show that the film-coupled NPs provide a transmission spectrum that can be tailored by varying the geometry (the size of the NPs and/or the thickness of the spacer). We perform both experimental spectroscopy and numerical simulations of individual NPs positioned over Au film, finding excellent agreement between experiment and simulation. The waveguide mode description serves as a starting point to explain the optical properties observed.