Here we report on the DNA-templated self-assembly of conducting gold nanowires between gold electrodes lithographically patterned on a silicon oxide substrate. An aqueous dispersion of ...4-(dimethylamino)pyridine-stabilized gold nanoparticles was prepared. These nanoparticles recognize and bind selectively double-stranded calf thymus DNA aligned between the gold electrodes to form a linear nanoparticle array. Continuous polycrystalline gold nanowires are obtained by electroless deposition that enlarges and enjoins the individual gold nanoparticles. The above nanowires were structurally characterized using a range of electron and scanning probe microscopies and electrically characterized at room temperature using a standard probe setup. The results of these characterizations show these wires to be 20 nm high and 40 nm wide, to be continuous between interdigitated gold electrodes with an interelectrode spacing of 0.2 or 1.0 μm, and to possess a resistivity of 2 × 10-4 Ωm. These DNA-templated nanowires, the smallest reported to date, exhibit resistivities consistent with reported findings and current theory. The use of DNA as a template for the self-assembly of conducting gold nanowires represents a potentially important approach to the fabrication of nanoscale interconnects.
This discussion paper aims to set out the key challenges and opportunities emerging from distributed manufacturing (DM). We begin by describing the concept, available definitions and consider its ...evolution where recent production technology developments (such as additive and continuous production process technologies), digitisation together with infrastructural developments (in terms of IoT and big data) provide new opportunities. To further explore the evolving nature of DM, the authors, each of whom are involved in specific applications of DM research, examine through an expert panel workshop environment emerging DM applications involving new production and supporting infrastructural technologies. This paper presents these generalisable findings on DM challenges and opportunities in terms of products, enabling production technologies and the impact on the wider production and industrial system. Industry structure and location of activities are examined in terms of the democratising impact on participating network actors. The paper concludes with a discussion on the changing nature of manufacturing as a result of DM, from the traditional centralised, large-scale, long lead-time forecast-driven production operations to a new DM paradigm where manufacturing is a decentralised, autonomous near end user-driven activity. A forward research agenda is proposed that considers the impact of DM on the industrial and urban landscape.
We describe a fully programmable Electrostatic Tactile (ET) feedback system that delivers a range of tactile textures to a mobile display. The ET system is a robust, thin, and optically transparent ...structure that can be overlaid unobtrusively on top of a display screen. The system exploits the phenomenon of electrovibration to create a controllable frictional force between a user's fingertip and the surface. The system enables the realization of localized tactile information delivered to the user's skin directly, without moving parts. A tactile image is formed in accordance with the visual information displayed (virtual textures, tactile silhouettes, etc.). The magnitude and pattern of the frictional force on the display can be programmed to correspond to the images shown on the display and actual coordinates of the touch interaction in real time. This has been achieved using a variety of different materials, including those that are compatible with flexible devices.
This paper describes a novel strategy to make fully transparent, solid-state and flexible supercapacitors based on room temperature ionic liquid (RTIL) gel and ITO electrodes coated on transparent ...polymer substrate without a separator, which enables the roll-to-roll technique for fabrication of such supercapacitors as printable devices. This is the first type of transparent electrochemical double layer capacitor (EDLC) based on ionic liquid gel.
This paper reports on the synthesis of zinc oxide (ZnO) nanostructures and examines the performance of nanocomposite thin-film transistors (TFTs) fabricated using ZnO dispersed in both n- and p-type ...polymer host matrices. The ZnO nanostructures considered here comprise nanowires and tetrapods and were synthesized using vapor phase deposition techniques involving the carbothermal reduction of solid-phase zinc-containing compounds. Measurement results of nanocomposite TFTs based on dispersion of ZnO nanorods in an n-type organic semiconductor (6, 6-phenyl-C 61 -butyric acid methyl ester) show electron field-effect mobilities in the range 0.3-0.6 cm 2 V -1 s -1 , representing an approximate enhancement by as much as a factor of 40 from the pristine state. The on/off current ratio of the nanocomposite TFTs approach 10 6 at saturation with off-currents on the order of 10 pA. The results presented here, although preliminary, show a highly promising enhancement for realization of high-performance solution-processable n-type organic TFTs.
Nanowire lithography (NWL) uses nanowires (NWs), grown and assembled by chemical methods, as etch masks to transfer their one-dimensional morphology to an underlying substrate. Here, we show that ...SiO2 NWs are a simple and compatible system to implement NWL on crystalline silicon and fabricate a wide range of architectures and devices. Planar field-effect transistors made of a single SOI-NW channel exhibit a contact resistance below 20 kΩ and scale with the channel width. Further, we assess the electrical response of NW networks obtained using a mask of SiO2 NWs ink-jetted from solution. The resulting conformal network etched into the underlying wafer is monolithic, with single-crystalline bulk junctions; thus no difference in conductivity is seen between a direct NW bridge and a percolating network. We also extend the potential of NWL into the third dimension, by using a periodic undercutting that produces an array of vertically stacked NWs from a single NW mask.
We report on exploration of internanocrystal coupling in assemblies of CoPt3 nanocrystals (i.e., artificial atom solids) probed by variable temperature charge transport measurements. Nanocrystal ...devices can be tuned in situ from Mott insulating to metallic behavior using mild thermal annealing. Thermal analysis suggests that the observed insulator-to-metal transition is due to melting and reorganization of the nanocrystal ligand shells causing a reduction in mean internanocrystal distance and is not due to nanocrystal ligand desorption or nanocrystal sintering.
External magnetic fields direct the destabilization and anisotropic aggregation of CoPt3 nanocrystal dispersions, producing one‐dimensional nanocrystal microwires. These microwires comprise ...disordered assemblies of discrete nanocrystals (see Figure). The observed activated‐charge‐transport properties of the microwires are determined by charging of individual nanocrystals.
The electronic properties of metal nanocrystal quantum dot solids in the insulating state have been measured as a function of nanocrystal diameter under conditions of controlled inter‐nanocrystal ...separation. Such properties of these weakly coupled nanocrystal arrays (see image), in particular the array charging energy, can be manipulated through experimental control of the nanocrystal diameter and mean inter‐nanocrystal separation.
We report on charge transport through laterally contacted assemblies of weakly coupled, 10.2-nm-diameter CoPt3 nanocrystals, where the shortest conducting paths consist of fewer than five ...nanocrystals. High-resolution electron microscopy reveals that the mean inter-nanocrystal separation can be reduced in situ through the use of mild thermal annealing without melting or sintering the nanocrystals. Devices annealed at 150 °C show measured resistances that are several orders of magnitude lower than that for unannealed assemblies, which is attributable to increased inter-nanocrystal tunneling. Variable-temperature dc electrical characterization demonstrates that these devices act as Mott insulators with transport characteristics governed by single-electron charging energies of the electrically isolated nanocrystals. Observed scaling behavior of low-temperature current−voltage characteristics indicates transport through current-carrying networks with dimensionality greater than two dimensions and also reflects the finite geometric disorder in the nanocrystal assembly.
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