Large‐Scale “Surface‐Programmed Assembly” of Pristine Vanadium Oxide Nanowire‐Based Devices

Abstract

Nanowires and nanotubes are drawing a tremendous amount of attention due to their potential applications in various nanoscale devices, such as field-effect transistors (FETs), [1±4] chemical and biological sensors, [5±8] nanoprobes, [9] and nanocables.[10] Divanadium pentoxide (V 2 O 5 ) nanowires or nanotubes have been utilized in FETs, [11] sensors, [12,13] spintronic devices, [14] and nanolithography templates. [15,16] However, previous reports have only shown the fabrication of a few devices, so the lack of a mass-production method is holding back their practical applications. Since nanowires are usually synthesized in a solution or powder form, individual nanowires have to be picked up and assembled onto the substrate to build functional devices, which cannot be achieved by conventional microfabrication strategies. Previous techniques used for nanowire assembly include flow-cell methods, [17] electromagnetic-field alignment, [18] biomolecular methods, [19] etc. [20±23] However, since these methods often rely on external forces to precisely align nanowires, it can be a time-consuming task to produce a large number of nanowire circuits with arbitrary orientations. In addition, the surface functionalization of nanowires in some techniques may even change the properties of the nanowires. Herein, we report a simple but efficient method named ªsurface-programmed assemblyº for high-precision assembly and alignment of a large number of pristine V 2 O 5 nanowires on solid substrates. In this strategy, positively charged surface molecular patterns are utilized to assemble and align millions of V 2 O 5 nanowires over a large surface area, while neutral surface molecular patterns are utilized to avoid any unwanted adsorption of nanowires. This method does not rely on any external force for nanowire alignment, and it is compatible with conventional microfabrication processes. Significantly, we demonstrate precision assembly and alignment of V 2 O 5 nanowire arrays and nanowire-based devices over a large surface area (~1 cm 1 cm). This method may pave the way toward industrial-level production of V 2 O 5 nanowire-based devices for practical applications. Figure 1 shows the schematic diagram of our strategy. First, we patterned the substrates with a self-assembled monolayer (SAM) of molecules with positively charged and neutral terminal groups. For example, on Au surfaces, we utilized cysteamine or 2-mercaptoimidazole (2-MI) as a positively charged SAM molecule, while 1-octadecanethiol (ODT) was utilized as a neutral molecular species. On SiO 2 surfaces, aminopropylethoxysilane (APTES) and 1-octadecyltrichlorosilane (OTS) were utilized as positively charged and neutral SAM molecular species, respectively. The molecular patterning process was carried out by patterning the first molecular species via dip-pen nanolithography (DPN), [24±26] Figure 1. Schematic diagram depicting ªsurface-programmed assemblyº of V 2 O 5 nanowires on solid substrates. a) Patterning a self-assembled monolayer with positively charged and neut...

Biomimetic Nanopatterns as Enabling Tools for Analysis and Control of Live Cells

“…Ordered/Disordered Surface Texturing -Self-Assembly Block Copolymer [ 89] -Patterned Nanotube [ 27] -Bio-MEMS [ 130] Nanopatterning of Functional Peptides /Proteins -Dip-Pen Nanolithography [19][20][21]30,35,36] -Nanocontact Printing [ 42] -Nanoimprinting [ 47] Figure 2 . A schematic representation of bio-functional surface array system patterned with chemical and biomechanical signaling and adhesion molecules.…”

Recent advances in large-scale assembly of semiconducting inorganic nanowires and nanofibers for electronics, sensors and photovoltaics

“…In addition, a simple method named ''surface-programmed assembly'' has also been reported by using electrostatic interactions. 22 In this strategy, positively charged surface molecular patterns are utilized to assemble and align negatively charged V 2 O 5 nanowires in an aqueous solution over a large surface area (B1 Â 1 cm 2 ), while neutral surface molecular patterns are utilized to avoid any unwanted adsorption of nanowires. Besides, a highly specific and selective assembly of nanowires on pre-patterned Au electrodes using DNA hybridization has been demonstrated recently.…”

Polycrystalline Vanadium Oxide Nanorods: Growth, Structure and Improved Electrochemical Response as a Li-Ion Battery Cathode Material

“…This reduces pulverization issues associated with bulk materials and consequently improves cycle life. 2 Vanadium oxides and their derivative compounds have attracted special attention because of their outstanding physical and chemical properties and potential applications in various areas, such as catalysts, [25][26][27][28][29][30] sensors [31][32][33][34][35][36][37][38] and electrodes. [39][40][41][42][43][44][45][46][47] The magnetic and optical properties of vanadium oxide nanotubes (VONTs) have also been thoroughly investigated.…”