Xu et al. Nanoscale Research Letters 2011, 6:525 http://www.nanoscalereslett.com/content/6/1/525 backside of the tip was coated with 20 nm Pt/Ir on top of 3 nm Cr. (see Figure S2 in Additional file 1) The scanning parameters (scan rate = 1 Hz; integral gain = 2; proportional gain = 3 to 4; deflection set point = 1 V; DC sample bias = 1 to 2 V) were set to these values for all experiments. Results and discussion Fabrication of metal nanowire arrays on a solid substrate were performed by cathodic electrodeposition from an electrolytic bath inside a commercial AAM [20]. The AAM was directly attached to a Au/Ti-coated solid sub- strate (either Si or glass) using a specially designed sam- ple holder as shown in Figure 1. A plastic O-ring was mounted on the edge of the AAM template to distribute the pressure evenly and to avoid the destruction of the AAM template due to its brittle nature. For the deposi- tion of patterned nanowire arrays on a solid substrate, the substrate was treated using the procedures shown in Figure 2. Initially, a thin conductive layer of Au/Ti (300:20 nm) was sputtered on the Si substrate followed by spin-coating of a thin layer (about 1.2 μm) of photo- resist. After exposure to UV light under a photolitho- graphic mask, the substrate was soaked in developer solution. The patterned underlying Au layer was exposed and used as a cathode. In order to achieve non- patterned nanowires on a large surface area, lithography process is not required; however the thin conductive layer of Au/Ti is necessary as a seed layer for the growth of nanowires. What the most important in this process is to ensure that the applied pressure is even across the entire sample or substrate because this will ensure even growth of nanostructures. Figure 1 Setup for electrodeposition. Page 3 of 7 Figure 2 Schematic for fabrication process of metal nanowire patterns on substrate. Figure 3 shows the Cu nanowire arrays within the AAM template on a Si substrate before and after mechanical polishing. Nanowires within the AAM over a large circular area (25 mm in diameter) were achieved as shown in Figure 3a. The overgrowth layer was manu- ally removed and the scanning electron microscopy (SEM) image of Figure 3b revealed that about 30% pores were fully filled according to the calculation of ratio of pores filled with nanowires to all the template pores on the top surface. This low filling ratio, which was initially observed from the top of the template, was due to the overgrowth of selected wires. The commercial template used in this study has branched pore structures [21] (on the filtration side) and therefore a few wires may reach