Micro & Nano Letters
Volume 12, Issue 2, February 2017
Volumes & issues:
Volume 12, Issue 2
February 2017
MEMS-based nanoreactor for in situ analysis of solid–gas interactions inside the transmission electron microscope
- Author(s): Hector Hugo Pérez Garza ; Diederik Morsink ; Jeff Xu ; Mariya Sholkina ; Yevheniy Pivak ; Merijn Pen ; Sander van Weperen ; Qiang Xu
- Source: Micro & Nano Letters, Volume 12, Issue 2, p. 69 –75
- DOI: 10.1049/mnl.2016.0290
- Type: Article
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A nanoreactor-based system for in situ analysis of solid–gas interactions inside the transmission electron microscope, referred to as the ‘climate system’, is introduced here. The latter uses an micro-electro mechanical systems (MEMS)-based device as a multi-functional sample carrier and microsized laboratory for simultaneous heating and gas experiments. To assemble the nanoreactor, two chips are sandwiched together to form a minimised chemical reaction chamber. The bottom chip contains a four-point-probe microheater, which controls and introduces the heating environment (up to 1300°C) around the sample. Similarly, it contains the spacers that define the height of the gas chamber. The top chip confines the gas in the microchamber while isolating it from the external environment. Both chips contain electron transparent windows that allow the electron beam to pass through for in situ imaging. The sample can be deposited or prepared directly on the windows, which are made of silicon nitride and can sustain pressures up to 1.5 bar and high temperatures while ensuring low background atomic resolution imaging.
Superoleophobic surfaces on stainless steel substrates obtained by chemical bath deposition
- Author(s): Liu Huang ; Jinlong Song ; Yao Lu ; Faze Chen ; Xin Liu ; Zhuji Jin ; Danyang Zhao ; Claire J. Carmalt ; Ivan P. Parkin
- Source: Micro & Nano Letters, Volume 12, Issue 2, p. 76 –81
- DOI: 10.1049/mnl.2016.0576
- Type: Article
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Superhydrophobic surfaces have shown great potential in domestic and industrial applications. However, these surfaces lose their superhydrophobic functions once being contaminated by oily liquids. In this work a simple chemical bath deposition method is reported to fabricate superoleophobic surfaces on steel substrates that repel both water and oil. The synthesis of superoleophobic surfaces involves the fabrication of the micro/nanometre-scale origami-ball-like structures on steel substrates, followed by the modification of low surface energy material. The fabricated surfaces have glycerol, peanut oil and hexadecane contact angles larger than 150° and roll-off angles smaller than 10°. This method is highly efficient because it takes only 5 min to create the surface re-entrant structures that are required by superoleophobicity. The prepared surfaces showed remarkable durability and retained superoleophobicity even after exposure to high and low temperatures (−30 and 100°C), and UV irradiation. This work will enrich the processing methods of the superoleophobic surfaces on stainless steel substrates.
Influence of substrate on structural properties and photocatalytic activity of TiO2 films
- Author(s): Dong Pan ; Haibo Fan ; Zan Li ; Siyi Wang ; Yinhao Huang ; Yang Jiao ; Hebao Yao
- Source: Micro & Nano Letters, Volume 12, Issue 2, p. 82 –86
- DOI: 10.1049/mnl.2016.0550
- Type: Article
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Titanium dioxide (TiO2) thin films were successfully grown on glass (TiO2/glass) and fluorine tin oxide (TiO2/FTO) substrates by using radio frequency magnetron sputtering. The as-prepared films were characterised and compared by X-ray diffraction, scanning electron microscopy, atomic force microscopy, ultraviolet–visible spectroscopy and photocatalytic test. It was found that the film deposited on FTO has better crystallinity, rougher superficial morphology, narrower optical bandgap and higher photocatalytic efficiency. The relationship between the factors and the photocatalytic performance has been analysed. Besides, it has been found that the internal electric field developed at the interface of TiO2/FTO may also play a positive effect on the improvement of the photocatalytic efficiency.
One-pot synthesis of flake Cu1.81S/C composite for high-performance supercapactiors electrodes
- Author(s): Haihua Hu ; Yanwei Sui ; Yaoyao Zhou ; Jiqiu Qi ; Fuxiang Wei ; Yezeng He ; Qingkun Meng ; Zhi Sun ; Yulong Zhao
- Source: Micro & Nano Letters, Volume 12, Issue 2, p. 87 –89
- DOI: 10.1049/mnl.2016.0389
- Type: Article
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One-pot fabrication of flake Cu1.81S/C composite with size of 300 nm was successfully demonstrated in this work. As the supercapacitor electrode material, the obtained Cu1.81S/C composite sample displayed good cycling stability of 83.6% capacitance retention after 1000 cycles and high specific capacitance of 617 F g−1 at current density of 0.5 A g−1. The excellent electrochemical performance is mainly attributed to flake nanostructure, which provides large electrode-electrolyte contact area and facilitates an easy access of electrolyte ions to the electrode surface. This result provides a new pathway for the fabrication of high-performance electrode material for supercapacitors.
Reliable and high quality adhesive bonding for microfluidic devices
- Author(s): Jingmin Li ; Chao Liang ; Hao Zhang ; Chong Liu
- Source: Micro & Nano Letters, Volume 12, Issue 2, p. 90 –94
- DOI: 10.1049/mnl.2016.0478
- Type: Article
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Some issues, such as the removing of air bubbles from bonding interface, microchannel clogging by adhesive, the methods to increase bonding efficiency, as well as the adhesive bonding of a multilayer chip, still limit the use of adhesive bonding in the mass fabrication of microfluidic devices. In this work, an automatic adhesive bonding machine is developed which can obviously increase bonding efficiency and quality as compared with the traditional manually methods. A bonding method which uses a soft pressing head to extrude the air bubbles from bonding interface is presented. The relationship between the adhesive film thickness and the channel clogging is investigated. The adhesive bonding of three types of two-layer microfluidic devices and a five-layer microfluidic device are studied. Results have shown that the uses of the soft pressing head can effectively removing the air bubbles from the bonding interface. The bonding ratios of all devices are above 95%. The channel residual depth, which is the channel depth excluding the protrusion height of the adhesive film within the channel, will increase to follow the increase in microchannel width and adhesive film thickness.
Synthesis of TiO2–Al2O3 and TiO2–Ta2O5 composite nanotubes on planar Si substrates
- Author(s): Karumbaiah N. Chappanda ; Mano Misra ; Swomitra K. Mohanty
- Source: Micro & Nano Letters, Volume 12, Issue 2, p. 95 –99
- DOI: 10.1049/mnl.2016.0516
- Type: Article
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Morphological studies of TiO2–Al2O3 and TiO2–Ta2O5 nanocomposite nanotubes synthesised on silicon substrates are presented here. Nanocomposite Ti–Al and Ti–Ta thin films were deposited on silicon substrates via simultaneous multi-target sputtering of Ti and Al targets or Ti and Ta targets, followed by anodisation in a fluorinated electrolyte. By increasing the Al or Ta concentration in the sputtered films, the morphology of the anodised films is changed from tubular oxides (with ripples on the outer walls) to well-aligned porous oxides (smooth walls, near zero gap between walls). By increasing the concentrations of Ta, formation of random Y-branched porous oxides in the anodised films is demonstrated. These nanotubes were synthesised on a planar substrates making them suitable for integrated circuits.
Determination of the alumina membrane geometrical parameters using its optical spectra
- Author(s): Lev B. Matyushkin ; Ekaterina N. Muratova ; Mikhail F. Panov
- Source: Micro & Nano Letters, Volume 12, Issue 2, p. 100 –103
- DOI: 10.1049/mnl.2016.0353
- Type: Article
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The transmission spectra for the porous alumina membranes prepared by electrochemical etching were investigated in a broad wavelength range from 0.2 to 12 μm. It is shown that the spectrum of the membrane maybe divided into regions enabling characterisation of average pore size and size distribution, the membrane thickness, and the presence of residual etching agent anions.
Preparation of multi-tip arrays on flexible substrates for large-scale microfabrication
- Author(s): Jialiang Chen ; Jiantao Liu ; Bingjun Yu ; Lei Chen ; Chenning Jin ; Linmao Qian
- Source: Micro & Nano Letters, Volume 12, Issue 2, p. 104 –108
- DOI: 10.1049/mnl.2016.0501
- Type: Article
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Scanning probe microscopy (SPM) provides an important way for micro/nanofabrication. Compared with single-tip mode, parallel multi-tip mode enables an effective way for microfabrication with large scale and high efficiency by SPM. During the preparation of multi-tip array, the height difference between different tips is quite difficult to be eliminated. In the present work multi-tip arrays were prepared on different flexible rubber substrates with good bonding strength. Finite element analysis was carried out based on a hyperelastic constitutive model for selecting a suitable rubber substrate for producing the multi-tip array, and the initial shear modulus C 10 should be from 0.5 to 17. A series of comparative fabrication experiments were conducted by different multi-tip arrays. The multi-tip array with flexible substrates fulfilling the prediction model can compensate obviously the height difference resulting from microsphere size, and the flexible substrate with a lower C 10 in this range is better for the scratching fabrication. Using the multi-tip array, large-scale surface patterning can be fabricated with low cost and easy operation. This work can promote the wide application of SPM and development of the surface texture engineering.
Effects of chirality on single-file water permeability and diffusivity through single wall carbon nanotubes
- Author(s): Alireza R. Binesh and Reza Kamali
- Source: Micro & Nano Letters, Volume 12, Issue 2, p. 109 –112
- DOI: 10.1049/mnl.2016.0384
- Type: Article
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In this work, molecular dynamics (MD) simulations of single-file water permeation through carbon nanotube (CNT) membranes have been performed and for a better understanding of the relationship between water transport performance of these biomimetic membranes and chirality of CNTs, the key parameters such as osmotic and diffusive permeability constants and diffusion coefficients are investigated. For this purpose, CNTs with approximately same diameters and different chirality from armchair to zigzag are used to perform 40 nanosecond MD simulations of these membranes. The resulting permeability and diffusivity characteristics of single-file CNT membranes showed that water permeability constant and diffusion coefficient increase by changing in the chirality of CNTs from armchair to zigzag, with approximately similar size in diameter. Finally, the presented results provide useful insights into the design of CNT water transporters with best performance.
Simple biosensing method to detect DMMP based on QCM transducer and acetylcholine esterase sensitive film
- Author(s): Wenying Ma ; Shi Tang ; Yaohua Wei ; Guangzhong Xie
- Source: Micro & Nano Letters, Volume 12, Issue 2, p. 113 –116
- DOI: 10.1049/mnl.2016.0497
- Type: Article
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A simple and stable method to detect dimethyl methylphosphonate (DMMP) was studied. Through direct monitoring of acetylcholinesterase (AChE) inhibition without histological substrate, the concentration of DMMP was sensitively detected. In the experimental setup, a liquid–gas interface was developed to improve the oscillation stability of quartz crystal microbalances (QCMs) and to prevent protein denaturation of AChE. AChE was immobilised on the surface of gold electrodes on QCM by creating a cross-linked gel with glutaraldehyde. Experimental results showed that the prepared biosensor had a frequency fall of ∼4 Hz when a concentration of 1 ng/ml increment occurred for liquid DMMP. Furthermore, the detection was repeatable and selective to only DMMP. Frequency response to DMMP in gas phase was also studied. The considerable frequency response and its complete recovery showed that the sensor had wide application potential in attack defence and public safety construction.
Influence of partial substitution for CB with MWNTs on performance of CB-filled NR composites
- Author(s): Huan Zhang ; Yintao Wei ; Zhenran Kang ; Guizhe Zhao ; Yaqing Liu
- Source: Micro & Nano Letters, Volume 12, Issue 2, p. 117 –122
- DOI: 10.1049/mnl.2016.0003
- Type: Article
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The effects of substituting carbon black (CB) with multiwall carbon nanotubes (MWNTs) on the structure and properties of natural rubber (NR)/CB composites is explored. Compared with NR/CB composites, NR/MWNTs/CB presents better filler dispersity and dynamic properties of the MWNT up to a certain concentration, as confirmed by scanning electron microscope, dynamic mechanical analyser and rubber processing analyser. Sample with 1 phr MWNTs shows obviously the highest tensile strength, 28.60 MPa, and almost the lowest heat build-up, only 9.6°C, and it is attributed to that not only large cross-link density and better filler dispersity but also high effective elasticity and large filler–rubber interaction. However, when the concentration is much higher, MWNTs tend to aggregate and lead to the poor efficiency to enhance the dynamic properties of rubber composites or even deteriorate the properties.
Coupling light into organic nanofibres via Raman scattering: waveguiding properties for near-infrared light
- Author(s): Ken Takazawa
- Source: Micro & Nano Letters, Volume 12, Issue 2, p. 123 –127
- DOI: 10.1049/mnl.2016.0448
- Type: Article
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A technique to couple near-infrared (IR) light into organic nanofibres that function as active optical waveguides by utilising Raman scattering is developed. Using this technique, light was coupled with λ = 800–910 nm into an organic nanofibre of thiacyanine (TC) dye and waveguiding properties in this wavelength range were investigated. A number of organic nanofibres, including TC nanofibres, have been found to function as active waveguides that propagate their own fluorescence along themselves. The waveguiding properties of these nanofibres have been extensively investigated in their fluorescence wavelength range, which is usually in the ultraviolet to visible region. However, their waveguiding properties outside of the fluorescence range are completely unknown because of the difficulties in coupling light from an external light source. The technique enables coupling of light with various wavelengths from the visible to the near-IR into nanofibre waveguides and investigation of the waveguiding properties at these wavelengths.
Synthesis of transferable nanoporous PtFe/Au film with enhanced electrocatalytic activity
- Author(s): Yingying Yin ; Jianwei Zhao ; Lirong Qin ; Yu Yang ; Lizhong He
- Source: Micro & Nano Letters, Volume 12, Issue 2, p. 128 –132
- DOI: 10.1049/mnl.2016.0539
- Type: Article
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An ordered nanoporous PtFe/Au film is synthesised via a simple two-step strategy based on sputtering and electrochemical deposition onto anodic aluminium oxide template. The morphology image of PtFe/Au film is characterised. The results reveal that the prepared porous film consists of ordered hexagonal array of nanoholes with a pore diameter of 40 nm and a periodic distance of 120 nm. PtFe/Au film after dissolving the template can maintain its integrality and is transferable. The PtFe/Au nanoporous film based electrode shows high catalytic activity for oxidation of methanol in alkaline ambiance which making it more attractive for fuel cell operations.
Synthesis of double-shelled hollow silica sphere with single-shelled hollow silica sphere and cetyltrimethyl ammonium bromide as dual templates
- Author(s): Gaoxin Zhou ; Zhilong Zhang ; Bo Chen ; Ying Wang ; Yu Ding ; Xiaolu Zhang ; Min Ji
- Source: Micro & Nano Letters, Volume 12, Issue 2, p. 133 –135
- DOI: 10.1049/mnl.2016.0415
- Type: Article
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In this work, single-shelled hollow mesoporous silica nanoparticles (SHMSNs) were first fabricated via template method and surface-protected etching strategy with the aid of cetyltrimethyl ammonium bromide (CTAB). Then, double-shelled hollow mesoporous silica nanoparticles (DHMSNs) were successfully synthesised based on single-shelled hollow mesoporous silica. The etching procedure using sodium carbonate as etchant, the surface-protected etching time and the influence of CTAB were discussed in detail. Experimental results showed that a warm and effective etching process could be achieved at 39°C for 3 h with CTAB protection. The resulting SHMSNs and DHMSNs were characterised by transmission electron microscope, scanning electron microscope, and nitrogen adsorption–desorption isotherms. In addition, it was proved that SHMSNs and DHMSNs possessed a well-defined hollow structure and uniform size. It is believed that the nanostructure feature some implication for creating other hollow structures.
Revised look at the effects of the channel model on molecular communication systems
- Author(s): Yi Lu ; Matthew D. Higgins ; Mark S. Leeson ; Yunfei Chen ; Paul A. Jennings
- Source: Micro & Nano Letters, Volume 12, Issue 2, p. 136 –139
- DOI: 10.1049/mnl.2016.0368
- Type: Article
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Molecular communications, where information is passed between the transmitter (TX ) and the receiver (RX ) via molecules is a promising area with vast potential applications. However, the infancy of the topic within the overall taxonomy of communications has meant that to date, several channel models are in press, each of which is applied under various constraints and/or assumptions. Amongst them is that the arrival of molecules in different time slots can be, or is, considered as independent events. In practice, this assumption is not accurate, as the molecules arriving in the previous slot reduce the possible number of molecules in the next slot and hence make them correlated. A more realistic performance of a molecular communication is analysed assuming correlated events. The key result shown is that the widely used model assuming independent events significantly overestimates the error rates in the channel. This result is thus critical to researchers who focus on energy use at the nanoscale, as the new analysis provides a more realistic prediction, and therefore less energy will be needed to attain a desired error rate, increasing system feasibility.
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