Online ISSN
1750-0443
Micro & Nano Letters
Volume 6, Issue 6, June 2011
Volumes & issues:
Volume 6, Issue 6
June 2011
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- Author(s): Lian-Yang Bai ; Yu-Ping Zhang ; Na Chen ; Jun Chen ; Xiao-Mao Zhou ; Lin-Feng Hu
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 337 –341
- DOI: 10.1049/mnl.2011.0047
- Type: Article
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An efficient visual detection method of Ba2+ using tiopronin (Tio)-modified gold nanoparticles (GNPs) in aqueous solution is reported. Tio could bind onto the GNP surfaces through the sulphur atom and the cross-linking of Tio-functionalised GNPs could be quickly accomplished by chelation upon the addition of Ba2+. Colour changes were observed from red to blue (or purple) within minutes with the increased concentration of Ba2+, in response to surface plasmon absorption of dispersed and aggregated nanoparticles. Using this colourimetric sensor, the concentration of Ba2+ was determined with a limit of detection lower than 1.5×10−6 M by the naked eye and could further be easily monitored by a UV–vis spectrometry. The possible mechanism of the aggregated Tio-GNPs was discussed by the addition of ethylenediaminetetraacetate and Ba2+ in different orders. - Author(s): R. Kitsomboonloha ; C. Ngambenjawong ; W.S. Mohammed ; M.B. Chaudhari ; G.L. Hornyak ; J. Dutta
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 342 –344
- DOI: 10.1049/mnl.2011.0160
- Type: Article
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A novel approach for optical filter implementation by tuning the plasmon resonance absorption of gold and silver nanoparticles in layer-by-layer (LBL) composite structures is presented. The LBL composite structures consisted of alternating layers of polyacrylic acid (PAA)-capped Au and PAA-capped Ag bi-layers. The results show clear spectrum tuning of green and blue peaks. Spectrum tuning can be extended when more metals or oxide nanoparticles are incorporated. - Author(s): Zhiyong Gao ; Ying Xiao ; Dapeng Wu ; Kai Jiang ; Fang Xu ; Yafei Yuan
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 345 –348
- DOI: 10.1049/mnl.2011.0065
- Type: Article
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Nano-sized GdPO4:Eu3+ hierarchical hollow spheres were successfully synthesised through chemical conversion using Gd(OH)CO3:Eu3+ nanospheres as templates. The obtained hollow spheres were composed of primary nanowires. Based on the time-dependent experiments, the hollow shells were proposed to be formed through chemical conversion from the precursor spheres. The as-prepared GdPO4:Eu3+ hollow spheres exhibit good photoluminescence performance. Furthermore, the current method can serve as a general way for the synthesis of rare-earth phosphates hollow spheres. - Author(s): C. Rodriguez ; E. Castro ; A. Martin ; J.R. Marín ; J. Berganza ; J.M. Cuevas
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 349 –352
- DOI: 10.1049/mnl.2011.0098
- Type: Article
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Polymer-iron hybrid magnetic microspheres with different carboxyl functionalisation for biomedical applications, thanks to suitable bio-recognition of the carcinoembryonic antigen (CEA), were prepared by the precipitation polymerisation of styrene-divinylbenzene-acrylic acid embedding iron oxide magnetic nanoparticles (∼10 nm). The influence of the acrylic acid concentration in the final size of copolymer and, consequently, in the efficiency of the antibody coupling between the primary amino group (–NH2) and the carboxyl functional groups (–COOH) in the polymeric surface were evaluated by varying monomers ratio with fixed content of magnetite nanoparticles. Particle size and morphology were investigated by scanning electronic microscopy and transmission electronic microscopy, as well as the saturation magnetisation values were measured in an electromagnet. The –COOH functionalisation and the covalent bounding of the antibodies, via detecting amino and carbonyl groups, were characterised by Fourier transform infrared spectroscopy. Regarding possible applications in molecular/cellular recognition and solid supports for immunoassays, efficient immobilisation of antibodies against CEA on particles surface via covalent bonding of the antibody and surface –COOH groups was demonstrated by immunochemistry techniques. - Author(s): Xiaokuo Yang ; Li Cai ; Hongtu Huang ; Peng Bai ; Weidong Peng
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 353 –357
- DOI: 10.1049/mnl.2011.0077
- Type: Article
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Magnetic quantum cellular automata (MQCA) is a nano-scale computational paradigm that utilises magnetic dipolar interaction and coupling to propagate and process binary information. Characteristics of signal propagation in MQCA circuits with pipelined clocking signals are evaluated for the purposes of fast and reliable logic operation. These circuits are simulated via the Landau–Lifshitz–Gilbert equations and object-oriented micro-magnetic framework tool. It is found that signal propagations in the thin nanomagnet circuits are blocked significantly as the damping parameter is increased; however, their switching times decrease as the damping parameter increases. Switching speeds of MQCA structures are improved as the thickness and damping parameter are increased. The results also show that the majority logic gate performs a complete reliable operation for nanomagnet thicker than about 20 nm, whereas for interconnect wire, thickness ranging from only about 20 to 25 nm introduces a successful operation. - Author(s): B.S. Randhawa and J. Singh
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 358 –362
- DOI: 10.1049/mnl.2011.0148
- Type: Article
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Nano-sized magnesium-doped Li–Zn mixed ferrite system, Li0.25Mg0.5−XZnXFe2.25O4 where X varies from 0 to 0.5 in steps of 0.1 has been prepared by novel solution combustion method using oxalyl-dihydrazide as capping agent and were characterised by X-ray diffraction, infrared, Mössbauer studies and transmission electron microscopy (TEM). The magnetic and electrical properties of the nanoparticles have been investigated by vibrating sample magnetometer and two-probe method, respectively, and results are compared with bulk materials. TEM and electrical studies reveal the formation of one-dimensional semiconducting nanorods that find an extensive application in lithium batteries and in the fast-paced miniaturisation of modern electronic devices. The variation in dielectric constant with frequency has been studied. - Author(s): F. Perdigones ; A. Luque ; J.M. Quero
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 363 –365
- DOI: 10.1049/mnl.2011.0150
- Type: Article
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This Letter presents the design, fabrication and experimental characterisation of a pneumatically actuated positive gain microvalve fabricated using SU-8 and gold over a printed circuit board substrate. The experimental results show that this microvalve has a n-channel metal-oxide semiconductor (NMOS)-like function in fluidic channel networks, with a maximum positive gain of 90 mL/(min·bar) and flow regulation of air from 3 to 40 mL/min for a working pressure of 10 mbar. The device has linear and saturation regions as p-channel microfluidic transistors. In addition, a new region named shock zone is obtained experimentally together with the rest, using air both as actuation and control fluid. The new shock zone corresponds to the breakdown region in microelectronic NMOS transistors. The proposed microvalve working as NMOS microfluidic transistor completes the field of transistors regarding the kind of channel. Furthermore, the device can be used as an active device in fluidics circuits and completes both the possibilities of flow control and microfluidic circuits design. - Author(s): Haibo Xie ; Yurun Fan ; Huayong Yang
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 366 –371
- DOI: 10.1049/mnl.2011.0091
- Type: Article
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A splitting and recombination-type micromixer (SAR-micromixer) based on the principle of fluid splitting, rearranging and recombination was optimised by the computational fluid dynamics (CFD) technique, fabricated and tested experimentally. Based on the split ratio, the mixing efficiency and the average pressure gradient, the branch angle of 70° and the zero straight channel length were chosen as the optimised structure parameters for an SAR mixing unit. The SAR-micromixer was fabricated by a standard photolithographic technique that is much easier than the fabrication of some 3D micromixer. To comprehensively evaluate the SAR-micromixer, its performance was compared with the straight channel micromixer (SCM) and the slant block micromixer (SBM) at various Reynolds numbers using dyed glycerol−water mixture fluids with various viscosities. Mixing experiments indicates that the mixing length of SAR-micromixer is much smaller than that of SCM and SBM; it is robust and efficient from slight viscous (0.00097 Pa s) to highly viscous (0.3792 Pa s) fluids. - Author(s): Hao Peng and Xiang Ling
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 372 –377
- DOI: 10.1049/mnl.2011.0069
- Type: Article
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Simulated gas–liquid two-phase horizontal flow characteristics were compared with corresponding experimental data taken from the Triplett. For the simulation of the two-phase flow characteristics, the well-known volume of fluid approach co-operated with the piecewise linear interface calculation interface reconstruction method was carried out. First, a variety of two-phase flow patterns were reproduced. The numerical results give good agreement with the flow regimes expected from the Triplett. Next to that, the two-phase pressure drops in micro-channels were analysed numerically by using the same computational fluid dynamics method. Also, the comparison of pressure drop among the numerical simulations, experimental data and the results calculated by homogeneous equilibrium model was presented. The agreement between numerical results and the existing experimental data was found to be satisfactory. So, it can be deduced that the numerical analysis procedure proposed here can achieve a better prediction for two-phase flow characteristics in micro-channels. - Author(s): Tao Han ; Qingping Xiao ; Dachuan Zhu ; Mingjing Tu ; Jin Zhang
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 378 –380
- DOI: 10.1049/mnl.2011.0197
- Type: Article
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In this study, the Ni–SiO2 composite microspheres were synthesised in situ in ethylene glycol. The nickel colloidal suspension was synthesised by hydrazine reduction in ethylene glycol with the addition of polyvinylpyrrolidone, and then coated on by silica using the modified Stöber process. The as-synthesised samples were characterised by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and vibrating sample magnetometer. XRD patterns showed that as-prepared nickel colloids are consistent with face-centred cubic phase and the broad peak at around 25° is attributed to amorphous SiO2 in Ni–SiO2 composite microspheres. TEM and SEM images indicated as-obtained Ni–SiO2 composite microspheres appear near spherical with a size of about 100–200 nm, and get well dispersed. Magnetisation curves demonstrated the saturation magnetisation value of as-prepared Ni–SiO2 composite microspheres is 4.4 emu/g with the content of nickel of about 20 wt.%. - Author(s): K. You and K. Nepal
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 381 –385
- DOI: 10.1049/mnl.2011.0168
- Type: Article
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In this Letter, the authors investigate the use of carbon nanotube-based field effect transistors (CNTFET) for the design of a ternary static random access memory (SRAM). The authors consider two designs – one using 8 transistors and the other using 14 transistors. Using circuit simulation models for CNTFETs, the authors show that both designs produce a functional ternary SRAM cell. The authors also measure the delay and power of the read-and-write operation of the ternary SRAM created using both models and show that the delays are comparable. - Author(s): H.M. Abduljalil ; M.A. Abdulsattar ; S.R. Al-Mansoury
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 386 –389
- DOI: 10.1049/mnl.2011.0115
- Type: Article
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Oxidised surface and core parts of SiGe nanocrystals are investigated using first-principle techniques that incorporate self-consistent Hartree–Fock method coupled with large unit cell (LUC) method to obtain the electronic structure of Bravais and primitive LUC multiples-based nanocrystals. Results show that lattice constant and ionicity of the core part show decreasing order as nanocrystals grow up in size. The smallest investigated nanocrystal is 2.5% larger in lattice constant and 15% larger in ionicity than the converged value of largest investigated nanocrystal. The lattice constant of both the surface and core has nearly the same value indicating good adherence of oxidised surface. Surface oxygen atoms absorb some of the electronic cloud of germanium and silicon surface atoms. Contrary to what one can expect, Si is the cation in this compound. The core energy gap increases and fluctuates as nanocrystals increase in size. The oxidised surface part on the other side has a dramatically lower gap. Oxygenated Ge- and Si-terminated nanocrystals have entirely different behaviour and properties. This includes a wider gap at the Si-terminated surface and highly ionised atoms. A bilayer with positively charged Ge and Si atoms are located at the Ge-terminated surface behind the oxygen layer. The present work suggests the addition of ionicity and lattice constant to the quantities that are affected by quantum confinement phenomenon. Some quantities, such as ionisation potential and affinity, continue to fluctuate indefinitely as nanocrystals grow up in size because of the generation of new shapes and surfaces. - Author(s): P.B. Kashid ; D.C. Kulkarni ; V. Puri
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 390 –392
- DOI: 10.1049/mnl.2011.0162
- Type: Article
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The present Letter deals with the investigation on the synthesis and properties of nanostructured mixed barium hexaferrites of M-type (BaFe12O19) and Y-type (Ba2Co2Fe12O22). The nanoparticles of mixed hexaferrite (Ba–M–Y) were obtained using co-precipitation technique with and without addition of polyethylene Glycol (PEG) during synthesis. The precipitate was calcined at 600°C for 6 h and characterised for structural, morphological, electrical and microwave properties. PEG acts as a template for the formation of hexaferrite nanoparticles. Significant reduction in crystallite size and grain size was obtained for Ba–M–Y synthesised in the presence of PEG template. Owing to PEG template the temperature-dependent resistivity showed negative temperature coefficient properties whereas without PEG the Ba–M–Y showed positive temperature coefficient properties. The microwave dielectric constant of Ba–M–Y–PEG (5.5 at 10.4 GHz) was higher than that of Ba–M–Y (4.1 at 10.4 GHz). Owing to PEG the microwave absorption increases to almost 50% from less than 1% in the10–10.7 GHz range. - Author(s): M.V. Balaban ; R. Sauleau ; T.M. Benson ; A.I. Nosich
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 393 –396
- DOI: 10.1049/mnl.2011.0176
- Type: Article
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The spontaneous emission of a molecular dipole in the presence of a thin dielectric microdisk is studied as a 3D solution of Maxwell's equations with two-sided generalised boundary conditions on the disk median plane, local energy finiteness and a radiation condition at infinity. Results presented show that the radiative and non-radiative decay rates display resonance maxima associated with the disk natural frequencies which can be explained through the effective-refractive-index approximation. The numerical solution is based on a set of coupled integral equations of the Fredholm second kind, with smooth kernel functions, obtained with the aid of the method of analytical regularisation. - Author(s): Xiaolei Zhang ; Liqun Du ; Yingli Zhu ; Chong Liu
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 397 –401
- DOI: 10.1049/mnl.2011.0045
- Type: Article
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During a SU-8 lithographic process, poor adhesion performance between the SU-8 photoresist and metal substrate usually contributes to the failure of the binding. More seriously, the lithography can even be completely compromised. This significantly restricts the improvement of image resolution and enhancement of depth-to-width ratio. Concerning this problem, an indentation method was adopted to test the adhesion strength between the SU-8 and stainless steel substrate in this study. By a dimensional analysis method, empirical formula accounting for indentation stress was deduced from Evans model. Interface fracture energy release rate was also obtained to characterise interface adhesion strength. Simulation was performed based on the commercial finite element package ANSYS, and its results were compared with corresponding indentation experiment results. The good agreement of these two results demonstrated the applicability of the modified empirical formula. Besides, the influence factors of adhesion performance were discussed. The result indicated that the existence of internal stress could prompt interfacial fracture, whereas increasing substrate roughness could improve interface adhesion strength. - Author(s): M. Yeganeh ; M. Motamedi ; M. Eskandari
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 402 –404
- DOI: 10.1049/mnl.2011.0169
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Nanostructured thin film copper fabricated by electron beam-physical vapour deposition (EB-PVD) method has unique properties, which make it different from the other deposits. In this study, nanostructured copper deposits were produced by EB-PVD as well as pulse plating techniques. Transmission electron microscopy was used for investigating the morphology of the deposited film. Surface roughness of deposits was measured by DEKTAK profilometer. Furthermore, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarisation methods were used to study the corrosive behaviour of the films. The surface morphology of corroded samples was obtained by scanning electron microscopy (SEM). Data obtained by polarisation, EIS and SEM suggested that corrosion resistance of EB-PVD deposit was higher than pulse plating deposit. This might be caused by its lower surface roughness and high purity owing to deposition in high vacuum. - Author(s): G. Momen and M. Farzaneh
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 405 –407
- DOI: 10.1049/mnl.2011.0222
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The present study investigates a very simple and inexpensive superhydrophobic coating preparation by spray-coating a silicone rubber/stearic acid mixture on a flat surface using a one-step process. The wettability of the coatings was found to be dependent on the surface morphology that was governed by the stearic acid concentration. A water static contact angle of 160°±3 and low contact angle hysteresis of 4°±1 was obtained for the surface coated with 43 wt% of stearic acid, on which water droplet easily roll off and bounce. At supercooled temperature (−15°C) the fabricated superhydrophobic coating showed an important delayed freezing time and icephobic behaviour. - Author(s): Lihua Liu and Yuris Dzenis
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 408 –411
- DOI: 10.1049/mnl.2011.0167
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Electrospinning produces continuous fibres with diameters from single nanometres to microns by jetting polymer solutions in high electric fields. Electrospun non-woven filamentary materials attract rapidly growing interest for broad range of applications. Properties of these materials depend on their nano- and microstructure that is determined in turn by the electric field and nanofibre collector. Despite critical importance, deposition of electrospun fibres on substrates has not yet been extensively studied theoretically and new methods of nanofibre collection continue to be developed mostly empirically. The objective of this Letter was to develop and demonstrate numerical simulation of electrospun nanofibre deposition on moving collectors. A dynamic model of nanofibre deposition onto a fast rotating drum was developed and used to simulate partial nanofibre alignment on this collector. The results were compared with the filamentary deposits in two classical stationary collection methods. Good agreement with experimental observations demonstrated predictive ability of simulations. The developed models can be used for the analysis of mechanisms of fibre deposition and alignment on substrates in various electric fields. Better understanding of dynamic nanofibre interaction with the electric field and collectors can lead to improved collector devices enabling one-step integrated nanomanufacturing of the designer nanofilamentary assemblies and architectures. - Author(s): H.N. Pishkenari ; S.H. Mahboobi ; A. Meghdari
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 412 –416
- DOI: 10.1049/mnl.2011.0173
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Models capable of accurate simulation of the microcantilever dynamics coupled with complex tip-sample interactions are essential for interpretation of the imaging results in non-contact atomic force microscopy (AFM). In the present research, a combination of finite element and molecular dynamics methods are used for modelling the AFM system to overcome the drawbacks of conventional approaches that use a lumped system with van der Waals interaction. To illustrate the ability of the proposed scheme in providing images with atomic resolution, some simulations have been performed. In the conducted simulations, a diamond tip is interacting with nickel samples having different surface plane directions. The results demonstrate the effectiveness of the proposed modelling method for measuring the surface topography with appropriate contrast and atomic details. - Author(s): Chunxiang Jiang ; Xiang Li ; Fei Yan ; Zhanhui Wang ; Qiaofeng Jin ; Feiyan Cai ; Ming Qian ; Xin Liu ; Lijuan Zhang ; Hairong Zheng
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 417 –421
- DOI: 10.1049/mnl.2011.0141
- Type: Article
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Microbubbles (MBs) coated by surfactant or polymer have been shown to be the most effective contrast agents for diagnostic ultrasound contrast imaging and targeted molecular imaging. With the development of both diagnostic and therapeutic applications of ultrasound contrast agents (UCAs), there is a demand for new preparation technologies to provide a high degree of control over MB size, composition, stability and uniformity in response. MBs produced by traditional methods, such as sonication or mechanical agitation, have poor control over MBs' size and uniformity. A polydisperse size distribution may have the inherent limitation of low acoustic backscattering efficiency and uncontrollable safety concern if used in vivo. This study presents successful production of five kinds of monodisperse MBs by flow-focusing method based on four flow-focusing units integrated microfluidic devices. These MBs act as a vehicle to carry fluorescent probe 6-coumarin, tumour-targeted peptide (LyP-1), paclitaxel, superparamagnetic iron oxide Fe3O4 nanoparticles and CdTe/ZnS quantum dots in the lipid shells, respectively. The sizes of MBs are controlled on the order of 2–7 µm by adjusting gas pressure and liquid flow velocity. These functional MBs have the potential applications in emerging areas, such as drug delivery, ultrasound molecular imaging and dual-modality imaging. - Author(s): S. Takei ; T. Ogawa ; C. Grant Willson
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 422 –424
- DOI: 10.1049/mnl.2011.0213
- Type: Article
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Step and repeat ultraviolet (UV) nanoimprint lithography has advantages such as metal-direct patterning, develop-less process, low line-edge-roughness and easy operation. However, the dirty-template-causing resist pattern peeling and the defect present challenges that must be resolved for mass-produce nano-devices. The approach to use the chemical adhesion by cationic polymerisation between resist material and the photoreactive underlayer during UV irradiation was investigated as the next generation of clean separation technology between template and resist material in step and repeat UV nanoimprint lithography. The obtained chemical adhesion between epoxy groups of the new fluorinated sol–gel silicon-based resist polymer and epoxy groups of novolac-type photoreactive underlayer was achieved with excellent 80 nm patterning dimensional accuracy by replication of imprint process cycles over 32 times, and was one of the key to reduce the resist pattern peeling and defect numbers. - Author(s): R. Bauer ; G. Brown ; D. Uttamchandani
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 425 –428
- DOI: 10.1049/mnl.2011.0113
- Type: Article
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Experimental investigations on the influence of a frame structure around an electrostatic comb-drive actuated micromirror are presented. The comparison between two 800 µm diameter mirrors, one framed and the other frameless, fabricated with a multi-user silicon-on-insulator process was carried out in relation to the dynamic movement behaviour and the static and dynamic curvature of the mirror surfaces. Both mirror types used in the study were carefully chosen to have a similar diameter and torsional resonant frequency of the order of 7 kHz and are actuated with 10 pairs of comb-fingers. The inclusion of the frame structure is shown to increase the homogeneity of the curvature of the mirror, with a difference of radius of curvature between the main axes of 1% compared to a 10% difference for the frameless mirror. The frame also increases the achievable maximum resonant tilt angle around the second main axis by a factor of three, at the same time avoiding nonlinear frequency responses (such as hysteresis) in the tilt angle against frequency curve. - Author(s): H.H. Dabaghi ; Y. Ganjkhanlou ; M. Kazemzad ; A.B. Moghaddam
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 429 –433
- DOI: 10.1049/mnl.2011.0188
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To study the relation between conductance, photoluminescence bands and structure of indium tin oxide (ITO), nano- and microparticles of ITO were synthesised using various methods, including hydrothermal, oxalate precursor decomposition and Pechini type sol–gel combustion methods. The resultant powders were analysed by X-ray diffraction (XRD), resistance measurement, photoluminescence (PL) spectroscopy and scanning electron microscopy techniques. The crystallographic and microstructural parameters of samples were refined from the XRD patterns utilising Rietveld method. Two PL bands were observed in 475 and 560 nm and it was found that the low-energy PL band intensity presents direct relation with conductivity of samples while the other one shows inverse relation. Pechini samples demonstrated the highest conductivity and low-energy PL band intensity, while hydrothermal sample has low conductivity. It was suggested that the low-energy PL band is the characteristics of excitons trapped in oxygen vacancy while the high-energy PL band is attributed to the excitons trapped in other defects centre. The colour of samples and data resulted from XRD pattern refinement were also validated. According to the refinement results and Popa's model, all samples show anisotropic micro-strain and crystallite size. It was also deduced that hydrothermal sample was textured in the 〈111〉 direction. - Author(s): Ning Gu ; Yang Cao ; Shuangqi Hu ; Riya Jin
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 434 –436
- DOI: 10.1049/mnl.2011.0163
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Hempflower-like Fe2O3 microspheres were synthesised by a simple method and its structure was determined by the scanning electron microscopy, X-ray diffraction patterns and Fourier transform infrared spectrum. The effect of reaction temperature and time on the formation and size of hempflower-like Fe2O3 microspheres was further investigated in detail. These results show that the formation of Fe2O3 microspheres with hempflower-like structure strongly depends on the reaction temperature and that the size (ca. 2–10 µm) of hempflower-like Fe2O3 microspheres can be easily controlled by adjusting the reaction time. Moreover, the synthesised hempflower-like Fe2O3 microspheres were used as water treatment for the water containing with Cu(II). The adsorption capacity of Fe2O3 microspheres was as high as 35.4 mg/g. The hempflower-like Fe2O3 microspheres was expected to apply in water treatment. - Author(s): Qi Zhang ; Junjie Qi ; Yunhua Huang ; Xin Li ; Yue Zhang
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 437 –440
- DOI: 10.1049/mnl.2011.0229
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The authors investigated the performance of ZnO nanowire-based metal–semiconductor field effect transistors (MESFETs) by focusing electron beam on the Schottky gate. The MESFET was fabricated by employing Tantalum as drain and source and by using Schottky barrier at tungsten–ZnO interface as the gate. As to IDS against VGS curves, once the gate was illuminated with electron beam radiation, crests with a redshift as VDS increased and a p-type semiconductor transistor behaviour were observed. At the critical points, the value of VDS−VGS revealed a linear behaviour with the increasing VDS. The authors attributed these results to the gain enhanced by electron beam radiation and carrier-trapping process, while the shift may be associated with the image-force lowing effect. - Author(s): D. Buttard
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 441 –443
- DOI: 10.1049/mnl.2011.0179
- Type: Article
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Nanoporous alumina film was realised on a silicon substrate. The structure investigated by scanning electron microscopy is presented and reveals homogeneous pores on the entire sample surface. The pore-cell is polygonal and has sometimes a hexagonal shape. The pore-cell is limited by six-edges, leading to alumina nanowires brushes normal to the substrate after an enlargement of the pores. Owing to the geometry of the initial pore structure, the resulting nanowires have an exponential shape with a foot larger than the top, leading to good mechanical behaviour. The alumina annealing has also been investigated by grazing incidence X-ray diffraction measurements and reveals the presence of the γ-Al2O3 phase for a temperature upper than 800°C. - Author(s): Shen Haijun
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 444 –447
- DOI: 10.1049/mnl.2011.0180
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The melting and axial compression of one (5, 5) single-walled boron nitride (BN) nanotube, as well as the (5, 5) BN tube embedded in one (10, 10) carbon nanotube, were simulated by molecular dynamics method. According to the calculated results, their differences in thermal-stability and compressive properties were discussed. It is shown that (i) the single-walled BN nanotube melts at about 4600 K, and the BN tube restricted in the carbon tube basically holds its configuration even at the high temperature of 5000 K; (ii) the restricted BN tube has much better anti-compression capability than the single-walled BN nanotube. - Author(s): A. Zandiatashbar ; C. Gaire ; C.R. Picu ; T.-M. Lu ; G. Subramanian
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 448 –450
- DOI: 10.1049/mnl.2011.0233
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One of the crucial factors that affects the performance of solid electrolyte – lithium-ion batteries is the electrode/electrolyte contact characteristics. Better contact implies greater ion transfer efficiency, leading to improved charge/discharge characteristics, and higher-power densities. In this study, the authors investigate the contact characteristics, viz. wettability, of germanium nanorod thin films initially by water, followed by polyethylene oxide (PEO)/water solution and PEO melt. The authors demonstrate that the electrode surface is hydrophilic, and considerably wettable, as evidenced by the contact angle for PEO/water solution and PEO melt, which are both below 25°. Electron microscopy was used to investigate the electrode/electrolyte contact area, and our results showed that PEO melt efficiently penetrates the inter-rod space, which is a further indication of considerable increase in the contact area. - Author(s): Qing Xie ; Dong En Zhang ; Feng Li ; Shan Zhong Li ; Xiao Bo Zhang ; Gui Quan Han ; Ai Ling Ying ; Zhi Wei Tong
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 451 –453
- DOI: 10.1049/mnl.2011.0205
- Type: Article
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p.
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Highly uniform four-fold shape Ce(OH)CO3 dendrites were successfully prepared in large quantities through a facile reduction hydrothermal approach. The samples were prepared from the reaction of Ce(NH4)2(NO3)6 with CO(NH2)2 at 160°C in a water–N2H4 complex. X-ray diffraction, scanning electron microscopy and transmission electron microscopy were used to characterise the products. The influence of the N2H4 on the dendrites formation was discussed. - Author(s): Qing-Yu Ma ; Rui-Fang Guan ; Guo-Zhong Li
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 454 –458
- DOI: 10.1049/mnl.2011.0165
- Type: Article
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p.
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Gold nanostructures are successfully synthesised under Langmuir monolayers of ionic liquid-type Gemini imidazolium surfactants [Cnim-4-Cnim][Br2] (n=10, 16) through interfacial reduction of AuCl4− by formaldehyde gas. The Au nanostructures are characterised using transmission electron microscopy and UV–vis spectroscopy. It is found that the concentration of HAuCl4 aqueous solution, the surface pressure and the length of the hydrophobic chains of the surfactants strongly influence the formation of Au nanostructures. A potential mechanism of such diverse morphologies is also discussed. - Author(s): Shanying Li ; Yang Jiang ; Binbin Wang ; Di Wu ; Junwei Li ; Yugang Zhang ; Ben Yang ; Xianan Ding ; Hongyang Zhou ; Honghai Zhong
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 459 –462
- DOI: 10.1049/mnl.2011.0219
- Type: Article
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The atmosphere compensating technique with an individual selenium source is, first, used in the growth of phosphorus-doped p-type ZnSe nanowires. The morphology and structure characterisations reveal that the as-synthesised ZnSe nanowires have a wurtzite structure with a diameter of about 160 nm, a growth direction of [001]. The electrical properties’ characterisations demonstrate that the selenium atmosphere compensation technique assisted with phosphorus-doping leads to a substantial action in p-type conductivity of ZnSe nanowires with a high mobility of 1.25 cm2 V−1 S−1 and carrier concentration of 1.47×1018 cm−3. The photoluminescence measurements show a dominant emission and two donor–acceptor pair emission. - Author(s): Sheng-Yen Wu ; Siu-Ming Yuen ; Chen-Chi M. Ma ; Yuan-Li Huang ; Chih-Chun Teng
- Source: Micro & Nano Letters, Volume 6, Issue 6, p. 463 –467
- DOI: 10.1049/mnl.2011.0138
- Type: Article
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In this study, both epoxy resin and multi-wall carbon nanotubes (MWCNTs) were modified with 3-isocyanato-propyltriethoxysilane (IPTES). Scanning electron microscopy and transmission electron microscopy microphotographs show that the MWCNTs dispersed well in the epoxy matrix. The molecular motion of silane-modified MWCNT/epoxy composites was studied using high-resolution solid-state 13C NMR. Results show that 1 wt% silane-modified MWCNT/epoxy composite exhibits less molecular motion than composite with a lower silane-modified MWCNT content. The glass transition temperature (Tg) of the neat epoxy is 192.6°C and increases to 212.5°C with 1 wt% IPTES-MWCNT content. Dynamic mechanical analysis data of the MWCNT/epoxy composites show the storage modulus at 50°C and the Tg of the IPTES-modified epoxy increased with IPTES-MWCNT content.
Visual detection of barium ions using tiopronin functionalised gold nanoparticles
Plasmon resonance tuning of gold and silver nanoparticle-insulator multilayered composite structures for optical filters
Facile synthesis of GdPO4:Eu3+ hierarchical hollow spheres via chemical conversion
Magnetic poly (styrene/divinylbenzene/acrylic acid)-based hybrid microspheres for bio-molecular recognition
Characteristics of signal propagation in magnetic quantum cellular automata circuits
Synthesis, characterisation and magnetic/electrical properties of the magnesium-doped Li–Zn nanoferrites
Pneumatically actuated positive gain microvalve with n-channel metal-oxide semiconductor-like behaviour
New 3D SAR micromixer based on 2D standard photolithographic technique
Computational fluid dynamics modelling on flow characteristics of two-phase flow in micro-channels
Synthesis of Ni–SiO2 composite microspheres in situ in ethylene glycol
Design of a ternary static memory cell using carbon nanotube-based transistors
SiGe nanocrystals core and surface electronic structure from ab initio large unit cell calculations
Modification of nanostructured mixed hexaferrite using a polyethylene glycol template
Accurate quantification of the Purcell effect in the presence of a dielectric microdisk of nanoscale thickness
Investigation of adhesion properties between SU-8 photoresist and stainless steel substrate
Comparison of corrosion resistance of nanostructured copper produced in vacuum and electrolytic solution in neutral chloride media
Simple process to fabricate a superhydrophobic coating
Simulation of electrospun nanofibre deposition on stationary and moving substrates
Hybrid finite-element method–molecular dynamics approach for modelling of non-contact atomic force microscopy imaging
Microfluidic-assisted formation of multifunctional monodisperse microbubbles for diagnostics and therapeutics
Study of fluorinated silicon-based resist material and photoreactive underlayer for defect reduction in step and repeat ultraviolet nanoimprint lithography
Comparison of the curvature homogeneity and dynamic behaviour of framed and frameless electrostatic X/Y scanning micromirrors
Relation between conductance, photoluminescence bands and structure of ITO nanoparticles prepared by various chemical methods
Controlled synthesis of hempflower-like Fe2O3 microspheres applied on the water treatment
Electron irradiation effect on the Schottky gate of ZnO nanowires-based field effect transistors
Elaboration of alumina nanowire field normal to a generic substrate
Thermal-stability and compressive properties of one boron nitride nanotube embedded in another carbon tube
Wetting of nanostructured germanium electrodes by polyethylene oxide
Chemical reduction route towards fabrication of four-fold shape Ce(OH)CO3 dendrites
Synthesis of gold nanostructures using Langmuir monolayers of ionic liquid-type Gemini imidazolium surfactants
Synthesis of p-type ZnSe nanowires by atmosphere compensating technique
Molecular motion, morphology and properties of 3-isocyanato-propyltriethoxysilane-modified multi-walled carbon nanotube/epoxy composites
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