Nanoscale convection assisted self-assembly of nanoparticle monolayer

Abstract

Micron and sub-micron particles tend to be self-organized into well-defined arrays during conventional convective assembly, however this technique hardly works for the assembly of tiny nanoparticles smaller than 10 nm into monolayered arrays. The intrinsic difficulty is mainly related to the evaporation and convections occurring at a much larger volume than nanoparticle size. As a result, multilayered nanoparticle arrays are usually created. In this paper, we report that solvent evaporation and nanoparticle convection are artificially confined in nanoscale grooves near a pipette's periphery and the grooves can help assemble parallel strips because of the uni-directional translation of the pipette. The stacking layer of each strip is correlated with the grooves' diameter, thus the nanoparticle monolayer is fabricated in the tiny grooves. The narrowest strip width observed experimentally is geometrically limited by the effective diameter of the charged nanoparticles in gold colloid because nanoparticle convections from the inner chamber to the pipette's periphery will not occur within the grooves finer than the effective diameters.

Electrical conduction of nanoparticle monolayer for accurate tracking of mechanical stimulus in finger touch sensing

“…46 The entire quantity of the HAuCl 4 aqueous solution was utilized to calculate the nanoparticle concentration in gold colloids, which was estimated as 4.5 × 10 10 per ml. 47 Polyethylene terephthalate (PET) film with a scale of 30 × 10 × 0.09 mm treated by plasmon cleaning was selected as the flexible substrate to support the nanoparticle monolayer in favor of characterizing the mechano-electrical properties of the strain gauge. 37 Convective assembly 37 was utilized to fabricate the nanoparticle strip with a width of 1-1.5 μm.…”

LSPR properties of metal nanoparticles adsorbed at a liquid–liquid interface

“…However, normal spontaneous Raman scattering is intrinsically very weak and often signals of sufficient quality for structural information analysis from the interface are difficult to attain unless extra enhancements are provided. Fortunately, the interface between two immiscible liquids has been confirmed as an important means of generating two dimensional self-assemblies of metal nanoparticles, [6][7][8][9][22][23][24][25][26][27] and localized plasmon resonance (LSPR) has been experimentally observed for a planar close-packed assembly of gold nanoparticles adsorbed at the water-1,2-dichloroethane interface. 11 These metal nanoparticles, with suitable LSPR bands, are capable of enhancing the efficiencies of Raman scattering by as much as 10 6 -10 10 fold if the exciting laser has an appropriate wavelength.…”

Nanohybrids of Gold Particles

“…This effect occurred spontaneously when the specimens were prepared by drop-casting using a regular glass pipette which should not affect the self-assembly. [73] No annealing was performed. The polymer shells cannot be seen directly in high magnifications, as would be the case with larger nanohybrids [74] or cores of materials with less electron-interaction, [75] but their presence causes the gold cores to be evenly spaced from each other.…”