Evaporative self-assembly of gold nanorings via a surface acoustic wave atomization

Ring of close packed gold nanoparticle arrays offers many fascinating properties that are not found in others assembly patterns. One of the most fantastic features of this unique organization is its ability to reroute shorter wavelengths of light in the visible region of electromagnetic spectrum, making it a very promising nanophotonic components for guiding light at the true nanoscale. Also, the creation of ring with gold nanoparticles can be used to make the world's smallest biosensors possible for multiple disease detection. Herein, we demonstrate a new paradigm for generating rings of CTAB-capped gold nanorods with the implementation of surface acoustic wave (SAW) atomization. With the ultrafast microfluidics actuation, the SAW atomizer can rapidly generate submicron fluids and efficiently form ring arrays onto desired substrates in less than 1s via the evaporative self-assembly process. The technique is able to provide a rational control over the of microfluids size distributions to engineer the smaller monodisperse rings arrays at micrometer scale. This microfluidics-assisted evaporative self assembly approach is also applicable to DNA-capped gold nanoparticles. The non-uniform mass distribution of ring is formed upon the pinning of contact line to substrates during a far-fromequilibrium dewetting process. Our method opens an avenue towards the ring assembly of gold nanoparticles in their ultimate microscopic minimal threshold to facilitate the generation of metamaterials.