Xu et al. Nanoscale Research Letters 2011, 6:525 http://www.nanoscalereslett.com/content/6/1/525 AAM and Si substrate, this results in a further step to remove the barrier layer, weak bonding between AAM and Si or even the detachment of the AAM from the Si surface have been observed if the barrier were not prop- erly removed [17]. It would also be very difficult to achieve large area uniform nanowire arrays on a solid substrate using the AAM template prepared by the above techniques, due to the difficulty in achieving uniform Al thickness over a large area, and of maintaining appropri- ate homogeneity of the template’s pore channels [18]. Recently, Taberna [19] attached a commercial AAM to a smooth copper foil as an electrode without using any conductive glue between AAM template and the copper foil. In this work, another thicker copper foil was put on the top of AAM and worked as an anode with a cellulose paper separator between the AAM and anode copper foil. Copper nanowire arrays, directly attached to the smooth copper foil were achieved. Theoretically, this method can also achieve ultra-long nanowires on other solid substrates, but this setup requires a flat anode which is not process friendly when mesh type anodes are required. Furthermore, it is not easy to get homoge- neous nanowire arrays with a large area due to the pore blocking effect of the cellulose paper, specifically when the template’s pore diameters are comparable to the width of the cellulose fibres. Nano-pillar gold arrays on a gold-coated glass substrate have also been achieved using a similar procedure [19]. However, the length of these nano-pillars was less than 1 μm. So far, no nano- wire arrays with length above 9 μm on Si or glass sub- strate have been achieved by this template method. In this paper, we report an effective procedure using a new setup for the fabrication of ultra-long metal nanowire arrays directly onto Si and glass substrates. Both copper and silver nanowires were fabricated using this setup. The length of these nanowire arrays can be up to 30 μm with length uniformity in an area covering up to 25 mm in diameter. This technique when combined with litho- graphy technology enabled micrometre-size-patterned nanowire array pads on a glass substrate to be fabri- cated. The strong bonding between nanowires and the bottom substrate was demonstrated by a tensile stress test, performed on the large area nanowires and the subsequent scanning acoustic microscopy (SAM) analy- sis on patterned nanowires. Furthermore, conductive atomic force microscopy analysis on the nanowire-AAM composite was performed to show the uniform conduct- ing properties of the composite and to prove that the each wire was electrically connected to the substrate. Experimental details Electrodeposition Electrodeposition of copper nanowires was carried out at room temperature at a constant current with a Page 2 of 7 density of 1.0 mA/cm2. Electrodeposition usually takes about 5 to 12 h from an electrolytic bath where a typical copper bath consists of 200 g l-1 of CuSO4.5H2O and 20 g l-1 of H2SO4 and a silver bath consists of 16 g l-1 of Ag2SO4, and 224 g l-1 of potassium thiocyanate. A two electrode cell was used for deposition and copper or Ag foil was used as counter electrode. The deposition was performed at a stirring speed of 500 rpm at room tem- perature. The commercial AAM used in this paper are Anodisc™ membrane filter with a 200-nm nominal pore diameter from Whatman plc (Maidstone, Kent, UK). To obtain nanowire arrays on substrate, the tem- plate was removed in 6.0 M KOH, washed with plenty of de-ionised water and dried in air. Pull-off adhesion tensile test The adhesion testing was carried out using an Elcometer 110 P.A.T.T.I. pneumatic tester according to the ASTM D4541-95e1 standard. A Ag nanowire-AAM on Si sam- ple was selected to avoid the effect of oxidation of the copper nanowire tips. The sample size was 11 mm in diameter. The diameter of the test stud was 8.16 mm which is related to 0.52-cm2 test area. To run the adhe- sion test, the stud was attached to the Ag nanowire- AAM surface with Araldite epoxy adhesive as shown in Figure S1a (see Additional file 1). The Si wafer was attached on a flat metal base plate as shown in Figure S1b (see Additional file 1). For execution of a pull-off test, the stud of the test equipment has to be firmly attached to the nanowire-AAM surface. To ensure this, the surfaces of the stud and the nanowire-AAM compo- site were polished using a coarse sand paper and subse- quently cleaned in acetone before applying the adhesive epoxy. After the sample was mounted, the specimen under test was pulled perpendicular to the wafer sub- strate until some part of the structure under ruptures. SAM characterization SAM characterization was carried out by SONIX HSl000 with software IC5.98d and transducers with nominal fre- quencies of 75 MHz. The transducer tip and sample were immersed in distilled water at room temperature. The test was performed with the Si substrate side up, in order to avoid signal scattering due to the rough sur- faces of the nanowires. Signals from the sample were transferred to a personal computer for advanced numer- ical data analysis. Conductive AFM characterization Conductive AFM characterization was performed using a Dimension D3100 scanning probe microscope. The tip used in this study was electrically conductivity probes made from 0.01 to 0.025 Ωcm antimony (n)-doped Si. The nominal tip radius is 20 nm and the front and