(50b) Assembly of Gold Nanowires on Gold Nanopad Arrays: Simulation and Experiment

Nanowires (NWs) have a large aspect ratio and available surface area, which has made them beneficial for applications in biosensors, electronic/optic devices and power storage devices. However, realization of many of these applications requires NWs to be positioned and oriented through an assembly process. Hence, it is essential to develop assembly strategies and techniques to achieve desired structures. Self-assembly techniques can be utilized to assemble NWs over a wide range of sizes in the absence of an externally applied driving force (i.e., fluid flow or magnetic or electric fields). In this work, we explored NW assembly using a patterned NW-substrate interaction. Experimentally, silica-coated Au nanowires (diameter 340 nm, lengths of 2.4 μm and 4.4 μm) are observed to assemble into various different patterns on parallel aligned, Au nanopads (widths of 2.4, 4.5 and 4.8 μm), which create a series of “stripes” on a glass substrate. We develop a model of this system considering van der Waals (vdW) and electrostatic interactions among NW and vdW interactions between NW and the nanopads. Due to roughness, NW accumulate extra charge at their ends, and this plays an essential role in describing the assembly. Monte Carlo simulations of assembly were performed based on this model. The assembly patterns and properties for various NW agree well with experimental results. The simulations indicate that while the patterned vdW attraction generated by the Au nanopads plays a leading role in bringing NWs onto the pads, interparticle forces dictate NW ordering on the pads.