Study of coffee stains for various nano concentrations

The gold nanorod arrays have been examined using helium ion microscopy (HIM) for different concentrations of nanoparticles. The assembled arrays were close-packed multilayers for the highest concentration of nanoparticles establishing continuous coffee stain deposits. At smaller concentrations, the deposited arrays of nanoparticles were mono-layered and broke the coffee stain effect after the initial deposition. The results were compared and examined in relation to interparticle forces. The droplet evaporation technique to self-assembly arrays in the CTAB environment, as well as the structural modification of the coffee stain ring with varying nanoparticle concentrations, will be presented. It is important to look at how the concentration of nanoparticles relates to the droplet contact angle and coffee stain width. HIM is often beneficial for establishing the real composition of surface deposits. The goal of this study was to study the effect of particle concentration that can lead to the construction of desired micrometer superstructures.