It can be seen that the

only technique being able to provide wafer-size colloidal crystals (tens of square centimeter in area) in some minutes is the spin-coating technique. It can be seen from this plot that the combination of large area, tens of monolayers of thickness, range of minutes to fabricate, good or excellent optical quality of the crystals, and 3D order is difficult to achieve in most of the techniques. In Figure 1, we have highlighted the results that we have achieved with the technique we are describing in this paper: the electrospray. Using this technique, we were able to deposit up to tens of monolayers, in a few minutes, in square centimeter size, with 3D order, and with good quality. These remarkable results, which are described in the sections Selleck MLN8237 below, compare quite well with the other state-of-the-art techniques reported in Figure 1. Thus, we can claim to have achieved a good compromise between large area and low deposition time, achieving good quality of the colloidal nanostructures. In this work, the deposition conditions, such as flow rate, solution concentration, electrical potential, LY2874455 molecular weight and distance between electrodes, are examined to find the optimal deposition conditions to create 3D self-assembly crystals. In the electrospraying deposition of particles on a substrate, several forces and physical phenomena are

involved. In the short range, electrostatic forces are important, in addition to surface tension and capillarity, to explain Methamphetamine particle adhesion to surfaces and particle chain, formation, or self-assembly. Coulombic and multipolar dielectrophoretic forces contribute to the total force acting on the particles, thereby affecting the adhesion regimes. The sign and magnitude of the dielectrophoretic component depends on the Claussius-Mossotty factor [28], which depends on the values of the permittivity of the particle and of the medium. In this work, we have observed a set of experimental conditions leading to net attractive forces between

particles, so they aggregate in the three dimensions of the layer growth. Scanning electron microscope (SEM) images and optical measurements are also shown to demonstrate the quality of the fabricated colloidal crystals. Methods The electrospray setup consisted of an infusion pump from B. Braun SA (click here Melsungen, Germany), an OMNIFIX (Braun) 5-ml syringe, a Hamilton needle (600-μm outer and 130-μm inner diameter; Hamilton, Bonaduz, GR, Switzerland), and an Ultravolt high-voltage bipolar source, −15 kV to +15 kV (Ultravolt, Ronkonkoma, NY, USA). The deposition area was placed inside a glove box with controlled N2 atmosphere. Figure 2 shows schematically the experimental setup. Figure 2 The electrospray setup. Schematic view of the experimental setup and an enlarged image of the tip of the needle with a Taylor cone and a jet of 4 μm circled in green.