Novel nanowires/nanoparticles/colloidal composite particles have great potential in applications such as thermal coatings, paints, inks, papers, adhesives, thin films, novel sensing materials, and hybrid emulsions for imaging or drug delivery. Furthermore, the hierarchical assembly of nanowires, which provide building blocks into different architectures, will surely lead to devices with higher structural complexity and new functionality—used in microelectronics fields such as nanolaser arrays, nanowire arrays as 2D photonic crystals and light-emitting nanowire/polymer composites. This type of assembly is a process that will enable the bridging of the recently discovered nanoscopic world to the existing microscopic/macroscopic worlds. The ability to manipulate these nanoscale building blocks is critical for the future of science and technology development.
The key to the success of nanotechnologies is assembly, namely the art of putting nanostructures xactly where one desires with the necessary connectivity. Nanostructure assembly is challenging because of the incompatibility of pertinent length scales— “nano” versus “macro.” The fluidic assembly scheme has become a popular topic in the R&D community, aiming to explore a sufficient control to allow for the fabrication of simple networks and the macroscopic patterning of nanowires/nanoparticles. The research community must develop generalized assembly techniques that go well beyond current capabilities if nanowires, rods, belts, and tubes are to see widespread technological application in optoelectronics and computing. For example, to arrange vast numbers of 1D nanostructures on solid surfaces is done through Langmuir–Blodgett assembly. In the LB technique, uniaxial compression of a nanowire–surfactant monolayer floating on an aqueous phase causes the nanowires to align and pack over a large area. The aligned monolayer can then be transferred to a solid surface. Repeated transfers of different types of nanowires can produce functional nanowire lattices.