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Reports that pulse-induced nanometer-scale lithography has been performed on graphite surfaces that were in contact with pure water or other organic liquids. Observation of reproducible control over the pit diameter in aqueous solutions.

Wafer scale (cm2) arrays and networks of nanochannels were created in polydimethylsioxane (PDMS) from a surface pattern of electrodeposited gold nanowires in a master-replica process and characterized with scanning electron microscopy (SEM), atomic force microscopy (AFM), and fluorescence imaging measurements. Patterns of gold nanowires with cross-sectional dimensions as small as 50 nm in hnight and in, tins in width were prepared on silica subsirates using the process of lithographically patterned nanowire electrodeposition (LPNE). Thtie nanowire patterns were then employed at masters for the fabrication of inverse replica nanochannels in a special formulation of PDMS. SEM and AFM measurements verified a linear correlation between the widths and heights of the nanowires and nanochannels over a range of 50 to 500 nm. The PDMS replica was then oxygen plasma-bonded to a glass substrate in order to create a linear array of nanofluidic channels (up to 1 mm in length) filled with solutions of either fluorescent dye or 20 nm diameter fluorescent polymer nanoparticles. Nanochannel continuity and a 99% fill success rate was determined from the fluorescence imaging measurements, and the electrophoretic injection of both dye and nanoparticles in the nanochannel arrays was also demonstrated. Employing a double LPNE fabrication method, this master-replica process was also used to create a large two-dimensional network of crossed nanofluidic channels. [ABSTRACT FROM AUTHOR]

Arrays of nanowires of an electronically conductive polymeric affinity medium tailored to the detection of Fe(III) are prepared, and their properties for detecting Fe(III) are evaluated. This polymeric affinity medium consists of poly(3,4-ethylenedioxythiophene) (PEDOT) into which an iron chelator, deferoxamine (DFA), has been doped during the polymerization process. PEDOT-DFA nanowires are potentiostatically deposited from a solution containing both EDOT and DFA using lithographically patterned nanowire electrodeposition (LPNE). The through-nanowire electrical resistance of PEDOT-DFA nanowires is measured as a function of the Fe(III) concentration. In parallel with measurements on PEDOT-DFA nanowire arrays, the electrochemical impedance of PEDOT-DFA films is characterized as a function of the Fe(III) concentration and the frequency of the impedance measurement in order to better understand the mechanism of transduction. PEDOT-DFA nanowires detect Fe(III) from 10-4 to 10-8 M with a limit of detection of 300 pM (calculated) and 10 nM (measured). [ABSTRACT FROM AUTHOR]

We describe the fabrication of arrays of nanowires onglass inwhich a gold core nanowire is encapsulated within a hemicylindricalshell of manganese dioxide. Arrays of linear gold (Au) nanowires arefirst prepared on glass using the lithographically patterned nanowireelectrodeposition (LPNE) method. These Au nanowires have a rectangularcross-section with a width and height of ≈200 and 40 nm, respectively,and lengths in the 1 mm to 1 cm range. Au nanowires are then usedto deposit MnO2by potentiostatic electrooxidation fromMn2늉溶⨧, forming a conformal, hemicylindrical shellwith a controllable diameter ranging from 50 to 300 nm surroundingeach Au nanowire. This MnO2shell is δ-phase andmesoporous, as revealed by X-ray diffraction and Raman spectroscopy.Transmission electron microscopy (TEM) analysis reveals that the MnO2shell is mesoporous (mp-MnO2),consisting of a network of ≈2 nm fibrils. The specific capacitance, Csp, of arrays of gold:mp-MnO2nanowires is measured using cyclic voltammetry.For a mp-MnO2shell thickness of 68 ±3 nm, core:shell nanowires produce a Cspof 1020 ± 100 F/g at 5 mV/s and 450 ±70 F/g at 100 mV/s. The cycle stability of this Csp, however, is extremely limited inaqueous electrolyte, decaying by >90% in 100 scans, but after ovendrying and immersion in dry 1.0 M LiClO4, acetonitrile,dramatically improved cycle stability is achieved characterized bythe absence of Cspfadefor 1000 cycles at 100 mV/s. Core:shellnanowires exhibit true hybridenergy storage, as revealed by deconvolution of Cspinto insertion and noninsertion components. [ABSTRACT FROM AUTHOR]

The formation of a nanometer-scale chemically responsivejunction(CRJ) within a silver nanowire is described. A silver nanowire wasfirst prepared on glass using the lithographically patterned nanowireelectrodeposition method. A 1–5 nm gap was formed in this wireby electromigration. Finally, this gap was reconnected by applyinga voltage ramp to the nanowire resulting in the formation of a resistive,ohmic CRJ. Exposure of this CRJ-containing nanowire to ammonia (NH3) induced a rapid (<30 s) and reversible resistance changethat was as large as ΔR/R0= ()138% in 7% NH3and observable down to 500ppm NH3. Exposure to water vapor produced a weaker resistanceincrease of ΔR/R0,H2O= ()10–15% (for 2.3% water) while nitrogen dioxide (NO2) exposure induced a stronger concentration-normalized resistancedecrease of ΔR/R0,NO2= (−)10–15% (for 500 ppm NO2). The proposed mechanism of the resistance response for a CRJ, supportedby temperature-dependent measurements of the conductivity for CRJsand density functional theory calculations, is that semiconductingp-type AgxO is formed within the CRJ andthe binding of molecules to this AgxOmodulates its electrical resistance. [ABSTRACT FROM AUTHOR]

The Seebeck coefficient, S, and the electrical conductivity, σ, of electrodeposited poly(3,4-ethylenedioxythiophene) (PEDOT) nanowires and thin films are reported. PEDOT nanowires were prepared by electropolymerizing 3,4-ethylenedioxythiophene (EDOT) in aqueous LiClO4 within a template prepared using the lithographically patterned nanowire electrodeposition (LPNE) process. These nanowires were 40−90 nm in thickness, 150−580 nm in width, and 200 μm in length. σ and S were measured from 190 K to 310 K by fabricating heaters and thermocouples on top of arrays of 750 PEDOT nanowires. Such PEDOT nanowire arrays consistently produced S values that were higher than those for PEDOT films: up to −122 μV/K (310 K) for nanowires and up to −57 μV/K (310 K) for films. The sample-to-sample variation in S for 14 samples of PEDOT nanowires and films, across a wide range of critical dimensions, is fully explained by variations in the carrier concentrations in accordance with the Mott equation. In spite of their higher |S| values, PEDOT nanowires also had higher σ than films, on average, because electron mobilities were greater in nanowires by a factor of 3. [ABSTRACT FROM AUTHOR]