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Micro & Nano Letters, IET

Issue 4 • Date December 2007

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Displaying Results 1 - 10 of 10
  • Aerodynamically assisted jetting: a rapidly emerging microfabrication methodology

    Publication Year: 2007 , Page(s): 78 - 84
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (622 KB)  

    Processing science and technology can have an immense influence on advancing a field of research, with the power to bridge the physical with the life sciences. An emerging processing science is reported, which is completely driven by aerodynamic forces that are brought about by a pressure difference over an orifice. Free jets formed by this methodology had previously been investigated for single-phase media for relatively low applied chamber pressures. Applying this technology to materials science implies that the media generally or in most cases would be multiphase in nature having high viscosity. Developmental studies on this jetting route demonstrate the promise this processing methodology shows in handling multi-phase high-viscosity media (nano- suspensions). Furthermore, the investigations extend to elucidating the protocol to manipulate operational parameters together with the rheological properties of the multi-phase media to generate a near-mono distribution of composite droplets and threads for deposition. This is most important if this technique is to play a pivotal role in materials science and engineering. The results presented here give birth to a novel microfabrication by drop/thread-and-place approach by way of aerodynamically assisted jetting. View full abstract»

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  • Studies on electromagnetic interference shielding characteristics of metal nanoparticle- and carbon nanostructure-filled polymer composites in the Ku-band frequency

    Publication Year: 2007 , Page(s): 85 - 89
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (445 KB)  

    The dispersion behaviour and electromagnetic interference (EMI) shielding properties were investigated for metal nanoparticle- and carbon nanostructure-filled polymer composites. It was observed that carbon nanostructure-polymer composites exhibited a much higher shielding performance than Ag nanoparticle-polymer composites at the same filler loading. The results also showed that Ag nanoparticle-polymer composites could exhibit an ideal shielding performance only with a very high Ag loading (> 30 wt%). The experimental data exhibited that the shielding effectiveness of the polymer composite containing 5 wt% carbon nanotubes could reach more than 20 dB in the measured frequency region, indicating such composites can be applied to the practical EMI shielding materials. In addition, some possible approaches to further improve the shielding performance of carbon nanotube-polymer composites were proposed and discussed. View full abstract»

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  • Preparation of ethyl cellulose nanoparticles from nano-emulsion obtained by inversion at constant temperature

    Publication Year: 2007 , Page(s): 90 - 95
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (291 KB)  

    A new method for the preparation of nanoparticles from nano-emulsions using a low- energy emulsification method based on phase inversion at constant temperature (catastrophic inversion) is described. This method does not require any special equipment such as high-pressure homogenisers. The method is demonstrated for the preparation of ethyl cellulose nanoparticles containing pyrene (a microviscosity and micropolarity probe) as a hydrophobic model molecule. The nano-emulsions were prepared using a combination of non-ionic surfactants: Polyglycerol fatty acid ester (decaglycerol mono laurate) and sorbitan ester (Span 20), volatile organic solvent (toluene) and ethyl cellulose. Toluene was evaporated from the nano-emulsions, resulting in ethyl cellulose nanoparticles 50-120 nm in size. The emission colours of the pyrene-embedded nano-emulsions changed from blue to violet after the evaporation of the toluene because of the absence of excimers. This method may be applied for the preparation of a variety of polymeric nanoparticles in which functional molecules are embedded within the particles. View full abstract»

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  • Printable high-speed thin-film transistor on flexible substrate using carbon nanotube solution

    Publication Year: 2007 , Page(s): 96 - 98
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (218 KB)  

    A printable high-speed thin-film transistor (TFT) fabricated on a regular plastic transparency film is proposed. The carrier transport layer of the TFT is an ultrapure carbon nanotube (CNT) thin film of high density (> 1000 CNTs per mum2) formed at room temperature by dispensing a tiny droplet of an electronic-grade CNT solution, which does not contain any surfactant. This CNT-TFT exhibited a high-modulation speed of 312 MHz and a large current-carrying capacity beyond 20 mA. A unique ink-jet printing compatible process demonstrated herein would enable mass production of large-area electronic circuits on any virtually desired flexible substrate at low cost and high throughput. View full abstract»

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  • MEMS-based packaging of a UV-LED array

    Publication Year: 2007 , Page(s): 99 - 102
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (448 KB)  

    A packaging solution that accurately positions a microlens array over a UV-LED array for the purpose of either collimating or focusing the light emitted by the LEDs is presented. The assembled device can be used for mask-free lithography or for postfluorescence lifetime imaging of biological samples. The microdevice proposed permits the simultaneous dynamic monitoring of the microlens array in the vertical direction through electrostatic actuation and in the horizontal direction through magnetic actuation. Displacements of more than 70 mum can be achieved for the vertical actuation with less than 1% deviation over 17 h. The device, manufactured through a modified UV-LIGA process, can either be postprocessed on top of the UV-LED array or be temporarily connected to the optoelectronic component depending on whether continuous monitoring of the microlens array is required. View full abstract»

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  • Fabrication of a nanophotonic quantum dot waveguide and photodetector integrated device

    Publication Year: 2007 , Page(s): 103 - 106
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (256 KB)  

    The authors present the design and fabrication of a nanophotonic waveguide and photodetector integrated device by molecular self-assembly of nanocrystal quantum dots (QD) and two different nano-gap formation techniques, namely electromigration-induced break-junction technique and electron beam lithography nano-gap patterning. A QD waveguide with ^50 nm width integrated with a nano-scale QD photodetector is achieved. A comparison is made between the two nano-gap techniques. In addition, a method to achieve high alignment accuracy for nanophotonic integration is discussed. View full abstract»

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  • Computing the Szeged index of third and fourth dendrimer nanostars

    Publication Year: 2007 , Page(s): 107 - 110
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (159 KB)  

    Let e be an edge of a graph, G, connecting the vertices u and v. Define two sets N1(e|G) and N2(e|G) as N1(e|G) = {x isin V(G)|d(x, u) < d(x, v)} and N2(e|G) = {x isin V(G)|d(x, v) < d(x, u)}. The number of elements of N1(e|G) and N2(e|G) are denoted by n1(e|G) and n2(e|G), respectively. The Szeged index of the graph G is defined as Sz(G) = SigmaeisinE(G)n1(e|G) n2(e|G). In this Letter, the Szeged index of third and fourth dendrimer nanostars is computed. View full abstract»

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  • Stress-strain behaviour of carbon nanotubes under cyclic loading

    Publication Year: 2007 , Page(s): 111 - 114
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (206 KB)  

    The behaviour and failure of carbon nanotubes (CNTs) under cyclic loading conditions are of high interest because of the potential use of CNTs as nanoscale building blocks of synthetic biomaterials, electromagnetic devices or polymer composites. Very limited work has been reported on this topic, although substantial research has been published on the mechanical strength, plastic deformation and failure mechanisms of CNTs. The authors show theoretically for the first time the stress-strain behaviour of CNTs under cyclic tensile and compressive loads by numerical simulation. Nonlinear elasticity, preconditioning (stress softening) and hysteresis characteristics have been reported most recently on multiwalled CNT blocks. It is found that elastic instability (local and global buckling) has a large influence on the stress-strain behaviour of CNTs under cyclic compression, whereas the cyclic strength remains unchanged under cyclic loading. The residual defect-free morphological deformation is considered as the primary mechanism responsible for the cyclic failure of CNTs. View full abstract»

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  • Characterisation and application of BPR-100 thick photoresist

    Publication Year: 2007 , Page(s): 115 - 117
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (267 KB)  

    BPR-100 thick photoresist was characterised by spin speed, exposure time, ultra-violet light (UV) absorption, development time and reactive ion etching (RIE) rates. This photoresist has been found to be highly stable in chemical baths and as a mask for RIE. The thickness of the resist varies with spin speed from 15 to 90 mum with a single spin. Optical and scanning electron microscopy images show vertical sidewalls and crack-free resist surfaces with a production-type reproducibility. An aspect ratio of 3:1 was achieved under optimum conditions. View full abstract»

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  • Erratum

    Publication Year: 2007 , Page(s): 118
    Save to Project icon | PDF file iconPDF (17 KB)  
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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