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Chen Y.,Monash University | Chen Y.,Melbourne Center For Nanofabrication | Zi O.,Swinburne University of Technology | Gu M.,Swinburne University of Technology | And 2 more authors.
Advanced Materials | Year: 2013

Metallic membranes of about 2.5 nm thick but with macroscopic lateral dimensions have been successfully fabricated from ultrathin gold nanowires. Such metallic nanomembranes are transparent, conductive and mechanically strong, with an optical transmittance of 90-97%, an electrical resistance of ∼1142 kΩ sq-1, and a breaking strength of ∼14 N m-1 with a typical atomic force microscope probe. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Nishijima Y.,Yokohama National University | Rosa L.,Swinburne University of Technology | Juodkazis S.,Swinburne University of Technology | Juodkazis S.,Melbourne Center For Nanofabrication
Optics Express | Year: 2012

We analyze the localized surface plasmon resonance spectra of periodic square lattice arrays of gold nano-disks, and we describe numerically and experimentally the effect of disorder on resonance width, spectrum, and EM field enhancement in increasingly randomized patterns. The periodic structure shows a narrower and stronger extinction peak, conversely we observe an increase of up to (1-2)×102 times enhancement as the disorder is gradually introduced. This allows for simpler, lower resolution fabrication, cost-effective in light harvesting for solar cell and sensing applications. We show that dipole-dipole interactions contribute to diffract light parallel to the surface as a mean of long-range coupling between the nano-disks. © 2012 Optical Society of America.


Friend J.,Melbourne Center For Nanofabrication | Yeo L.Y.,Melbourne Center For Nanofabrication
Reviews of Modern Physics | Year: 2011

This article reviews acoustic microfluidics: the use of acoustic fields, principally ultrasonics, for application in microfluidics. Although acoustics is a classical field, its promising, and indeed perplexing, capabilities in powerfully manipulating both fluids and particles within those fluids on the microscale to nanoscale has revived interest in it. The bewildering state of the literature and ample jargon from decades of research is reorganized and presented in the context of models derived from first principles. This hopefully will make the area accessible for researchers with experience in materials science, fluid mechanics, or dynamics. The abundance of interesting phenomena arising from nonlinear interactions in ultrasound that easily appear at these small scales is considered, especially in surface acoustic wave devices that are simple to fabricate with planar lithography techniques common in microfluidics, along with the many applications in microfluidics and nanofluidics that appear through the literature. © 2011 American Physical Society.


Altissimo M.,Melbourne Center For Nanofabrication
Biomicrofluidics | Year: 2010

Electron beam lithography (EBL) is one of the tools of choice for writing micro- and nanostructures on a wide variety of materials. This is largely due to the fact that modern EBL machines are capable of writing nanometer-sized structures on areas up to mm 2. The aim of this contribution is to give technical and practical backgrounds in this extremely flexible nanofabrication technique. © 2010 American Institute of Physics.


Davis T.J.,CSIRO | Davis T.J.,Melbourne Center For Nanofabrication | Hendry E.,University of Exeter
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

We show theoretically that localized surface plasmons can generate optical fields with a chirality exceeding that of circularly polarized light by a factor of 50. This superchiral optical field can be formed from linearly polarized light incident on nonchiral metal structures. We identify three mechanisms that lead to large optical chirality involving the coupling between the incident light and the evanescent fields of the surface plasmons. Two of these mechanisms create superchiral regions with nonzero average chirality suitable for the excitation of chiral molecules in solution. © 2013 American Physical Society.


Dentry M.B.,Monash University | Yeo L.Y.,RMIT University | Friend J.R.,Melbourne Center For Nanofabrication
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2014

Acoustic streaming underpins an exciting range of fluid manipulation phenomena of rapidly growing significance in microfluidics, where the streaming often assumes the form of a steady, laminar jet emanating from the device surface, driven by the attenuation of acoustic energy within the beam of sound propagating through the liquid. The frequencies used to drive such phenomena are often chosen ad hoc to accommodate fabrication and material issues. In this work, we seek a better understanding of the effects of sound frequency and power on acoustic streaming. We present and, using surface acoustic waves, experimentally verify a laminar jet model that is based on the turbulent jet model of Lighthill, which is appropriate for acoustic streaming seen at micro-to nanoscales, between 20 and 936 MHz and over a broad range of input power. Our model eliminates the critically problematic acoustic source singularity present in Lighthill's model, replacing it with a finite emission area and enabling determination of the streaming velocity close to the source. At high acoustic power P (and hence high jet Reynolds numbers ReJ associated with fast streaming), the laminar jet model predicts a one-half power dependence (U∼P1/2∼ ReJ) similar to the turbulent jet model. However, the laminar model may also be applied to jets produced at low powers-and hence low jet Reynolds numbers ReJ-where a linear relationship between the beam power and streaming velocity exists: U∼P∼ReJ2. The ability of the laminar jet model to predict the acoustic streaming behavior across a broad range of frequencies and power provides a useful tool in the analysis of microfluidics devices, explaining peculiar observations made by several researchers in the literature. In particular, by elucidating the effects of frequency on the scale of acoustically driven flows, we show that the choice of frequency is a vitally important consideration in the design of small-scale devices employing acoustic streaming for microfluidics. © 2014 American Physical Society.


Cappel U.B.,Monash University | Cappel U.B.,Imperial College London | Daeneke T.,Monash University | Bach U.,Monash University | And 2 more authors.
Nano Letters | Year: 2012

Solid state dye-sensitized solar cells (sDSCs) employing the hole conductor 2,2′7,7′-tetrakis-(N,N-di-p-methoxyphenyl-amine)-9,9′- spirobifluorene (spiro-MeOTAD) require the presence of oxygen during fabrication and storage. In this paper, we determine the concentrations of oxidized spiro-MeOTAD within devices under different operating and storage conditions by UV-vis spectroscopy. Relative concentrations of spiro-MeOTAD + were found to be greater than 10% after illumination for standard sDSCs, where no chemical dopant had been used in the solar cell fabrication but oxygen and lithium ions were present. We suggest that oxidized spiro-MeOTAD is created as a byproduct of oxygen reduction at the TiO 2 surface during cell illumination. Furthermore, we studied the effect of light soaking under different conditions and associated changes in spiro-MeOTAD + concentration on the solar cell measurements. Our findings give insights to photochemical reactions occurring within sDSCs and provide guidelines for which doping levels should be used in device fabrication in absence of oxygen. © 2012 American Chemical Society.


Juodkazis S.,Melbourne Center For Nanofabrication
International Journal of Nanomedicine | Year: 2012

The laser polymerization capabilities of biocompatible and cross-linkable materials using direct laser writing are discussed. Purpose: Cross-disciplinary highlight of synergy between medical applications and laser microfabrication. © 2012 Juodkazis, publisher and licensee Dove Medical Press Ltd.


Yeo L.Y.,Melbourne Center For Nanofabrication | Friend J.R.,Melbourne Center For Nanofabrication
Annual Review of Fluid Mechanics | Year: 2014

Fluid manipulations at the microscale and beyond are powerfully enabled through the use of 10-1,000-MHz acoustic waves. A superior alternative in many cases to other microfluidic actuation techniques, such high-frequency acoustics is almost universally produced by surface acoustic wave devices that employ electromechanical transduction in wafer-scale or thin-film piezoelectric media to generate the kinetic energy needed to transport and manipulate fluids placed in adjacent microfluidic structures. These waves are responsible for a diverse range of complex fluid transport phenomena - from interfacial fluid vibration and drop and confined fluid transport to jetting and atomization - underlying a flourishing research literature spanning fundamental fluid physics to chip-scale engineering applications. We highlight some of this literature to provide the reader with a historical basis, routes for more detailed study, and an impression of the field's future directions. Copyright © 2014 by Annual Reviews. All rights reserved.


Abbey B.,La Trobe University | Abbey B.,Melbourne Center For Nanofabrication
JOM | Year: 2013

This review summarizes the literature describing recent advances in the coherent x-ray sciences for the high-resolution characterization of materials. The principles and some of the main experimental techniques as well as their applications are discussed. The advantages of x-ray methods for characterizing 3D microstructures as well as for characterizing plasticity in the bulk become clear from the examples presented. Materials that exhibit size effects within the 0.1-10-μm range benefit enormously from these techniques, and development of the relevant x-ray methods will add to our fundamental understanding of these phenomena. Many of the ideas that have developed in the coherent x-ray science literature have been enabled through advances in x-ray source and detection technology, which has occurred over the past 10 years or so. It is a topic of considerable importance to consider how these techniques, which have matured rapidly, may be best applied to materials imaging in order to meet the growing needs of the community. As coherent x-ray methods for characterizing materials at multiple length scales have developed, several key applications for these techniques have emerged. The key breakthroughs that have been enabled by these new methods are discussed throughout this review, together with an examination of some of the problems that will be addressed by these techniques within the next few years. © 2013 The Author(s).

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