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Micro & Nano Letters, IET

Issue 9 • Date September 2011

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Displaying Results 1 - 19 of 19
  • Controllable synthesis of hierarchical ZnO microstructures via a hydrothermal route

    Page(s): 741 - 744
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (393 KB)  

    Hierarchical ZnO superstructures assembled by ZnO nanorods have been successfully constructed in mixed solvents of ethylene glycol (EG)-water via a facile hydrothermal method. ZnO nanostructures with dumb-bell-like and microsphere morphologies were obtained by only a change of the precursor concentration. The products were characterised by means of X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Raman scattering and room-temperature photoluminescence spectra. The possible formation mechanism of these hierarchical ZnO nanostructures is also proposed. View full abstract»

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  • Rapid pathogen detection using an organic field effect transistor

    Page(s): 745 - 748
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (381 KB)  

    A pentacene field effect transistor (FET) for the detection of DNA from pathogenic organisms is fabricated. The pentacene FET is an excellent candidate for disposable sensor applications because of its low-cost fabrication process and fast detection. A viral (λ-phage) genomic DNA was chosen as a model organism and its presence was successfully detected by probe DNA hybridisation on the pentacene layer. The process produced a dramatic change in the channel current and field-effect mobility of the devices. This result demonstrates the feasibility of our device as a disposable sensor for DNA hybridisation and can lead to the development of a biosensor for rapid pathogen detection. View full abstract»

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  • In situ method of densification for powder-based piezoelectric thick films for microelectromechanical system applications

    Page(s): 749 - 754
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (743 KB)  

    Piezoelectric (PZT) (Pb(Zr0.52Ti0.48)O3) thick film-based microtransducers demonstrate excellent piezoelectric performances. PZT thick films on Si-based substrate can be used as piezoelectric actuators and sensors with the introduction of microelectromechanical system technology and the screen printing method. However, the thick films made just by the screen printing method have high porosity compared with bulk product, and the PZT thick films on Si-based substrate have problems regarding degradation of active materials and interface properties owing to inter-diffusion or reaction between Si substrate and PZT materials at high temperature for sintering. Thus, the authors have fabricated screen printed PZT thick films on Si substrate using the screen printing method and sol infiltration for enhancing densification. Ethanol-based photo-cross-linkable sol and conventional diol-based sol were used to compare influence of patterning process. Thick films with relative high densities at low temperature, 800°C and without inter-diffusion and reaction between the layers and thick film were accomplished. Also, it was revealed that the PZT thick film treated by ethanol-based photo-cross-linkable sol showed better electrical properties as well as excellent patternability. View full abstract»

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  • Steps to fabricate 3D overhanging nanostructures using focused ion beam

    Page(s): 755 - 758
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (327 KB)  

    Novel methodologies to overcome some of the difficulties in standard deposition procedures in focused ion beam (FIB) systems to fabricate 3D nanostructures are described. The geometrical restriction put on by the position of electron and ion columns and the precursor gas needles in a conventional FIB chamber, complicates the 3D fabrication process. As case studies, wide vertical walls and overhanging bridge-type structures of tungsten are fabricated. The overhanging bridge-type structure of tungsten can be used as a nanofilament for producing heat within a few micrometre distances. The heat, produced in the filament, is sensed by a tungsten-platinum nanothermocouple fabricated underneath the filament. View full abstract»

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  • Dosimeter based on silver-nanoparticle precursors for medical applications with linear response over a wide dynamic range

    Page(s): 759 - 762
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (291 KB)  

    In this Letter the authors study a liquid detector based on Ag nanoparticles for dosimetry purposes. They use two different concentrations of silver nitrate (1 mM AgNO3) and sodium citrate (1 and 0.1% C6H5O7Na3) as precursors for the formation of Ag nanoparticles in an aqueous colloidal solution. The authors utilise a linear accelerator to expose the solutions to absorbed doses ranging from 0.5 to 120 Gy and they find that gamma radiation induces the synthesis of Ag nanoparticles already at 2 Gy, when the sodium citrate concentration is lowered to 0.1 . The authors find a correlation between shape/dimension of the Ag nanoparticles and the absorbed dose. More importantly, the authors show that the absorbance peak intensity of the Ag nanoparticles increases with the absorbed dose and that a linear dependence is achieved at the lower sodium citrate concentration. View full abstract»

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  • Optoelectronic property and sensing applications of crystalline nano/microwires of decacyclene

    Page(s): 763 - 766
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (275 KB)  

    The characterisation and potential sensing applications of nano- and microwires of decacyclene are reported in this study. Attenuated total reflection infrared and differential thermal analyses reveal that the nano/microstructures are composed of aggregated decacyclene molecules that are held by π-π interactions. Transmission electron microscopy images and the electron diffraction patterns show that, in the nanowires, the decacyclene molecules are oriented with their long axis perpendicular to the wires and the π-π stacking direction parallel to the wire. Cross-optical polarised microscopy results shows a birefringent crystal structure of the decacyclene crystalline wires. Fluorescent imaging shows that the crystalline wires might be used as a waveguide material. Both the conductivity and fluorescence of the nanobelts change selectively in the presence of vapour of nitrobenzene, a representative nitroaromatic, suggesting that the nanowires of decacyclene may be used for selective detection of explosives. View full abstract»

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  • Structural and optical properties of ZnO thin films prepared by sol-gel method

    Page(s): 767 - 769
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (401 KB)  

    In this Letter thin films of zinc oxide (ZnO) are prepared by sol-gel method and deposited on glass substrate to evaluate structural and optical properties of the film. The films were grown at different thicknesses in the range of 100-180-nm. The properties of layers were characterised using X-ray diffractometer (XRD), atomic force microscope (AFM) and optical spectrophotometer to evaluate the quality of the thin film for photovoltaic applications. The results from XRD pattern revealed that the grown films exhibit wurtzite structure with (002) preferential plane. The results from AFM data revealed that the films had nano-sized grains with a grain size from-25 to 60-nm depending on the film thickness. The optical spectrophotometer studies exhibited direct allowed transition with an energy bandgap of 3.12-3.02-eV for films with thicknesses of 100-180-nm, respectively. The refractive index as well as extinction coefficient of films was also measured. View full abstract»

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  • Non-destructive and controllable catalyst deposition of in situ growing carbon nanotubes onto the carbon fibre fabric

    Page(s): 770 - 773
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (358 KB)  

    To in situ grow carbon nanotubes (CNTs) on the surface of carbon fibre fabric (CFF) with suitable diameter and uniform distribution, controllable catalyst deposition is the key process. A controllable and non-destructive pre-treatment, that is, electrochemical oxidation pre-treatment, was explored to facilitate uniform `seeding` nano-sized catalyst particles on the surface of CFF without causing damage to carbon fibres. Main factors, such as voltage, concentration of electrolyte, electrolytic time, catalyst type and concentration of the catalyst precursor, were investigated. X-ray photoelectron spectroscopy tests indicated that voltage, concentration of electrolyte and duration of electrochemical treatment determined the distribution density of catalyst nanoparticles by controlling the concentration of the functional groups, while the diameter of catalyst particles was decided by the concentration of Fe(NO3)3 and CO(NH2)2. Besides, the diameter of catalyst particles could be modulated by adding Al(NO3)3 in the solution of the catalyst precursor. At the same time, to avoid cementite produced during the calcination and reduction process, the temperature should be controlled below 773 K. Scanning electron microscopy observations indicated that well-dispersed in situ grown CNTs could be obtained after CFF had been chemical oxidised at the voltage of 10 V for 10 s with 0.02 M NH4HCO3 as electrolyte and followed by catalyst deposition. View full abstract»

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  • Synthesis and characterisation of CuO nanorods via a hydrothermal method

    Page(s): 774 - 776
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (244 KB)  

    CuO nanorods were synthesised on a large scale via a simple hydrothermal method. CuCl2·2H2O and cetyltrimethylammonium bromide (CTAB) were used as the copper source and surfactant, respectively. The microstructure and morphology of the CuO nanorods were examined by X-ray diffraction, Raman spectrum, field-emission scanning electron microscopy, transmission electron microscopy (TEM) and UV-vis spectrum. The CuO nanorods were monoclinic, and their diameter and length ranged from 20 to 30 nm and 150 to 200 nm, respectively. High resolution TEM and selected area electron diffraction results indicated that the CuO nanorods grow along the [010] direction. A possible growth mechanism for the formation of CuO nanorods was proposed. The concentration of surfactant CTAB in the solution was found to be a critical factor on the CuO morphology during the hydrothermal stage. The bandgap of the CuO nanorods was calculated to be 2.01 eV from the UV-vis spectrum. View full abstract»

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  • Power VDMOS transistor with the step oxide trench breaks the limit line of silicon

    Page(s): 777 - 780
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (283 KB)  

    A power vertical double-diffusion metal-oxide-semiconductor (VDMOS) transistor is designed with the step oxide trench based on the oxide-bypassed concept proposed by Liang and co-workers. It is suitable for breakdown voltage below 300 V to obtain ultra-low specific on-resistance. The electric field of the drift region is modulated because of the new electric field peak introduced by the various thicknesses of sidewall oxide. As a result, the breakdown voltage was increased no less than 20 because of more uniform electric field distribution in the drift region, while the specific on-resistance was reduced by 40 60 resulting from the step oxide trench compared with the oxide-bypassed structure. The limit line of the silicon has been broken because the trade-off is improved between the breakdown voltage and the specific on-resistance. The low Ron,sp of 15.0 m mm2 with the breakdown voltage (BV) of 150 V and 28.0 m mm2 with the BV of 230 V in the proposed step oxide trench MOS are improved greatly compared to the Ron,sp of 163.4 m cm2 with the BV of 150 V and 475.75 m mm2 with the BV of 230 V in the conventional VDMOS. View full abstract»

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  • Synthesis and photoluminescence study of Ce3+/Dy3+-activated KLa(WO4)2 phosphors

    Page(s): 781 - 784
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (259 KB)  

    In this study, the authors report the synthesis of Ce3+- and Dy3+-activated double potassium lanthanum tungstates [KLa(WO4)2], prepared by solid-state diffusion method. The prepared phosphors were characterised by X-ray diffraction, scanning electron microscopy and photoluminescence (PL) techniques. The PL spectra of KLa(WO4)2:Dy3+ shows the emission peaks at 569 and 476 nm. KLa(WO4)2:Ce3+ showed the emission peaks at 388 nm. Excitation wavelengths of these Ce3+- and Dy3+-activated tungstates are in near-UV region, that is, Hg-free excitation. Accordingly, Ce3+- and Dy3+-activated KLa(WO4)2 may be the promising materials for solid-state lighting applications. View full abstract»

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  • Numerical investigation and optimisation of hollow-core photonic crystal fibre for optical trapping of fluorescent microparticles

    Page(s): 785 - 789
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (445 KB)  

    This Letter proposes and demonstrates the optical trapping of fluorescence sample in a transversely-probed microstructured hollow-core photonic crystal fibres (HC-PCFs). The transmission intensity distribution at the central core of liquid-filled HC-PCFs with different central wavelengths is monitored for both the transverse electric and transverse magnetic modes, with illumination in the Γ-M direction. Forces acting on a sphere located inside the central core along the transverse direction of these liquid-filled fibres are calculated and compared using finite-difference time-domain method and Maxwell stress tensor-based method. The proposed concept is illustrated by trapping fluorescent microsphere particles to the core of liquid-filled HC-PCF and the presence of sample particles is confirmed by fluorescence signatures. The obtained results indicate that the proposed concepts have tangible potential for developing novel optical manipulation and trapping inside HC-PCFs and are expected to find potential biomedical diagnostic applications. View full abstract»

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  • Influence of TiC nanoparticles on microstructures and properties of electrodeposited Ni??P coatings

    Page(s): 790 - 793
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (233 KB)  

    Electrodeposited composite coatings show large development potential, thanks to particular properties obtained by the incorporation of particles. In the present work, Ni-P and Ni-P/nano-TiC coatings were electroplated on steel substrates. X-ray diffraction technique, scanning electron microscopy, energy-dispersive analytical X-ray, microhardness, potentiodynamic polarisation and electrochemical impedance spectroscopy were utilised to study the influence of addition TiC nanoparticles and heat treatment on corrosion resistance and physical properties of the applied coatings. The TiC nanoparticles were found to be embedded in the Ni-P alloy matrix and post heat treatment resulted in NixPy phase precipitation which caused the increasing microhardness of deposits. Electrochemical impedance spectroscopy and polarisation tests showed that the addition of nano-TiC particles and proper heat treatment demonstrated significant increase in corrosion resistance of Ni-P coatings in 3.5-wt.- NaCl solution. View full abstract»

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  • Atomic force microscopy tip-sample interaction analysis using nanocontact mechanic models

    Page(s): 794 - 798
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (263 KB)  

    Various nanocontact mechanic models have been proposed for modelling of the atomic force microscopy (AFM) cantilever tip and its interaction with the sample. In this Letter, the role of adhesion force on tip-sample contact radius and applied load are compared using different nanocontact mechanic models including Hertz, Derjaguin-Muller-Toporov, Johnson-Kendall-Roberts-Sperling, Burnham-Colton-Pollock, Carpick-Ogletree-Salmeron, Pietrement-Troyon, Sun and Maugis-Dugdale. According to dynamics modelling of the AFM cantilever tip and its interaction with the sample by nanocontact mechanic models, the variation of applied load and tip-sample contact radius by applying cantilever base position displacement is discussed. In addition, influence of the AFM probe geometry is investigated. View full abstract»

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  • Resistance-switching behaviour in ZnO-Nb2O5 thin films for non-volatile memory application

    Page(s): 799 - 801
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (311 KB)  

    The microstructure and resistance switching characteristics of polycrystalline ZnO-Nb2O5 thin films prepared by the sol-gel method on indium tin oxide (ITO)/glass substrates at different annealing temperatures followed by annealing in oxygen have been investigated. The selected-area diffraction pattern showed that the deposited films exhibited a polycrystalline microstructure. The Pt/ZnO-Nb2O5/ITO/glass device exhibits reversible and steady bistable resistance switching behaviour with a narrow dispersion of resistance states and switching voltages. The resistance ratios of high-resistance state to low-resistance state were in the range of 1-2 orders of magnitude within 200 test cycles. View full abstract»

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  • Investigation of loading and release of guest molecules from hollow mesoporous silica spheres

    Page(s): 802 - 805
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (258 KB)  

    The authors report, for the first time, the investigation of loading and release of guest molecules from the hollow mesoporous silica (HMS) spheres by using confocal laser scanning microscopy (CLSM) technique. The HMS spheres with particle size of 800-1200-nm and peak pore size of 2.5-nm were well prepared by using the carbon spheres templating method. Using rhodamine 6G (Rho-6G) dye as guest molecules, the Rho-6G distribution in the HMS spheres after loading and time-dependent release from the HMS spheres were evaluated by the CLSM imaging and fluorescence intensity analysis. The results indicated that the guest molecules can diffuse into the hollow cores through the mesoporous channels on the shells, and the release of guest molecules from HMS spheres follows a diffusion-driven behaviour and exhibits a sustained release manner. Therefore this kind of HMS spheres as carriers has the potential for drug delivery. View full abstract»

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  • Facile synthesis and magnetic properties of cross α-Fe2O3 nanorods

    Page(s): 806 - 808
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (246 KB)  

    Novel cross α-Fe2O3 nanorods were obtained by forced hydrolysis of ferric chloride in the water solution system. The as-obtained products were characterised by X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectrum, Brunauer-Emmett-Teller and vibrating sample magnetometry. XRD results revealed that the product exhibited α-Fe2O3 phase. A comprehensive TEM analysis revealed that the cross structures consisted of α-Fe2O3 nanorods with an average length of 400 nm and diameter of about 75 nm. Magnetic hysteresis measurement reveals that the novel cross α-Fe2O3 nanorods display weak ferromagnetic behaviour with a remanence of 0.115 emu/g and a coercivity of 491.5 Oe at room temperature. View full abstract»

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  • Fabrication of polydimethylsiloxane microlens arrays by surface tension induced liquid separation

    Page(s): 809 - 811
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (367 KB)  

    This Letter presents a novel fabrication method to build polymer microlens arrays. The key mechanism of the fabrication process is surface tension, which induces liquid separation phenomenon when a post is immersed and detached from a bottom liquid mixture. The surface tension also acts on the formation of lens surface at liquid-air interface resulting in an excellent surface roughness. The surface profile of lenses is well fitted with an ideal lens profile. The other feature of the presented fabrication method is self-positioning of the lens into the post. The range of focal lengths was between 110.4 and 282.0--m, which were determined by three parameters such as a post radius, gap and bottom liquid thickness. In summary, the STILS method can be a powerful tool to create microlens arrays with a smooth surface and a high scalability for the future applications in optoelectronics or microfluidics. View full abstract»

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  • Solution combustion synthesis of Cu nanoparticles: a role of oxidant-to-fuel ratio

    Page(s): 812 - 815
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (270 KB)  

    Solution combustion synthesis technique is one of the novel techniques used to prepare nanoparticles, nanocomposite and ceramic oxides. The authors prove in this study the usefulness of the technique in producing copper nanoparticles. In solution combustion, the stoichiometric ratio, according to propellant chemistry, needs the oxidiser-to-fuel ratio to be unity. The combustion of cupric nitrate and citric acid at stoichiometric ratio results in copper nanoparticles. The copper nanoparticles were characterised by different techniques, such as X-ray diffraction, thermal gravimetry/differential thermal analyser, Fourier transform infrared, FT-Raman and scanning electron microscopy. The Cu nanoparticles get oxidised to Cu2O slowly at 250°C and to CuO at 530°C. The combustion of the reactants with lean and rich oxidant-to-fuel ratio (O/F) ratios results in mixed phases except in the 1:0.71 ratio. The phases in lean O/F ratios were Cu, CuO, Cu2O, whereas only CuO was present in rich O/F ratios. View full abstract»

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Aims & Scope

Micro & Nano Letters offers express publication of short research papers presenting research conducted at the forefront of micro- and nanoscale science, engineering and technology, with at least one dimension ranging from a few tens of micrometres to a few nanometres.

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Meet Our Editors

Editors-in-Chief
Professor Gwo-Bin Vincent Lee
National Tsing-Hua University, Taiwan

Professor Peter Dobson
University of Oxford, UK