The nanofabrication of nanometre-scale multiple-level structures by nanoimprint lithography and CF₄/O₂ etching rates was investigated for nanoelectro mechanical systems and three-dimensional (3D) wafer-level packaging. A TiO₂–SiO₂ sol–gel photocurable material with high titanium concentration of 20.9 wt% was developed for CF₄/O₂ etch selectivity with a pattern transferring carbon layer in a bi-layer process. The nanostructures of 3D micropatterns, holes with 200 nm diameter and 130 nm-wide dense lines with line edge roughness of ∼10 nm were provided. The CF₄/O₂ etching rate of the TiO₂–SiO₂ photocurable material was ∼3.7 times lower than that of the referenced SiO₂ sol–gel photocurable material. The CF₄/O₂ etch rates of titanium-based photocurable materials were confirmed for deep plasma etching processes.

A simple process for nickel nanoimprint stamp replication is proposed. Based on this process, the replication of a 15 × 20 mm nickel nanoimprint stamp with 60 nm grating structures was carried out. First, the nanograting structures on the master silicon stamp were transferred to a polymer substrate using the hot embossing process; then, a layer of nickel was sputtered to fill the nanostructures on the substrate surface and form the seed layer for the electroforming process; finally, the back plane of the replica is electroformed. The observation results show good correlation between the dimensions of the master stamp's features and the corresponding replicated features. The performance test result of the replicated stamp demonstrated that the mechanical strength of the replica is sufficient for the hot embossing process.

The microstructure and geometrical dimensions of the scales on a butterfly Papilio peranthus Fabricius wing are obtained using scanning electron microscopy and transmission electron microscopy. Two kinds of scales are found in a butterfly wing and the structural colour mainly comes from the cover scale. Different structural models of cover scale that are related to ridge and concavity are constructed and their corresponding optical properties are investigated using the finite-difference time-domain  method. It is concluded that the structural colour on the cover scale mainly comes from the sculpted multilayer structure and the ridge on the scale has few effects on the structural colour. When the curvature of the sculpted multilayer structure decreases, the dominant wavelength of colour will shift to a longer wavelength and move slower and slower. The two-dimensional planar multilayer model can be used to calculate the structural colour when the curvature exceeds a certain value.

Interdigitated microelectrodes (IDμE) are always used as the sensing structure of a biosensor to detect the hormone content in the human body. To increase the sensitivity of the IDμE biosensor, the authors provide an improved method that utilises IDμE with nanodot arrays, that is, the nanodot arrays are put into the inter-electrode gap in IDμE. The nanodot arrays can reduce the conducting distance between microelectrodes, thereby reducing the resistance to electricity and improve the sensitivity of biosensors. The improved biosensor is composed of IDμE and nanodot arrays: the IDμE is made by microelectro mechanical system (MEMS) technology, whereas the fabrication of nanodot arrays makes use of the nanosphere lithography (NSL) technology. Double Cr/Au bilayers are used to make a conjunction between the MEMS and NSL process. The biosensor based on the IDμE with nanodot arrays was used in the detection of low-level thyroid-stimulating hormone (TSH), and proved to provide about three times sensitive detection than the biosensor without nanodot arrays. The TSH detection limit of the biosensor based on the IDμE with nanodot arrays can reach 0.005 mIU/l. The improved biosensors can be used in the detection of other hormones, which are critical for disease intervention strategies.

A report is presented on the preparation of surface-functionalised nanosilica from silicon tetrachloride (SiCl₄, one of the major by-products in the polycrystalline silicon industry) by in-situ surface modification in aqueous solution. The approach uses both SiCl₄ and sodium metasilicate as the silicon sources to generate nanosilica, whereas the proportion of sodium metasilicate and SiCl₄ is adjusted to control the pH value of the reaction system. In this way, desired SiO₂ nanoparticles were in-situ surface-modified by hexamethyldisilazane as soon as they were generated in the reaction solution, which makes it feasible to prevent the severe aggregation of nanosilica that often happens during the hydrolytic process. The obtained nanosilica with uniform particle size distribution (mean diameter 35–40 nm) shows superhydrophobicity (a water contact angle of 165°) and excellent organic dispersibility. Thanks to the low cost of raw materials as well as the superhydrophobicity and lipophilicity of as-prepared nanosilica, its application for improving the selective penetration of oil is primarily investigated. The result shows that quartz sand modified by as-prepared nanosilica can separate diesel oil from water successfully, which could be significant for improving crude oil recovery efficiency.

The hexagonal rotor-like cerium carbonate hydroxide (CeCO₃OH) and CeO₂ nanostructures were successfully synthesised via a facile hydrothermal method using Ce(NO₃)₃ · 6H₂O as the cerium resource, HNO₃ additive to form an acidic solution, CO(NH₂)₂ as both precipitator and carbon source and polyvinylpyrrolidone as surfactant. Characterisation techniques using an X-ray diffractometer, scanning electron microscope, transmission electron microscope, X-ray photoelectron spectroscopy, thermogravimetric differential thermal analysis apparatus and UV–vis absorption spectrum have been used for studying the roles of Ce(NO₃)₃ · 6H₂O and HNO₃. It was found that the amount of Ce(NO₃)₃ · 6H₂O has an obvious effect on the morphology of the as-synthesised CeCO₃OH and CeO₂ nanostructures, whereas HNO₃ has a significant influence on the crystalline phase. CeO₂ has a higher UV absorption than as-synthesised CeCO₃OH, which is likely associated with the charge-transition between Ce³⁺ and Ce⁴⁺.

The electrocatalytic performance of commercial PtRu/C is significantly enhanced by directly mixing a few SnO₂ nanoparticles. The composite catalysts show enhanced CO oxidation, higher activity and better stability than commercial PtRu/C. Among the different ratios of SnO₂ nanoparticles (10–40%), the SnO₂–PtRu/C (20%) composite catalyst shows the best catalytic activity for methanol oxidation. The effect of temperature on methanol oxidation was also investigated and the apparent activation energy (E _a) value of catalyst was obtained. The results here suggest a simple route to enhance the catalytic efficiency for commercial PtRu/C catalyst.

Different shapes of silicon (Si) nanotip arrays using reactive ion etching with various mask patterns were fabricated, and the surface profile, surface roughness and quantitative etch characteristics of the Si nanotip were characterised. It was found that the geometry as well as etch characteristics of Si nanotip arrays could be modified by changing the initial mask patterns. Pyramidal and conical shaped Si nanotips could be obtained from square and circular mask patterns, respectively. The alternate square array pattern resulted in a Si nanotip with a wavy array whereas the honeycomb mask pattern resulted in a Si nanotip in a hexagonal array. In terms of etch rate, the circular pattern mask showed faster etching than the square patterns. Also, the parallel pattern showed faster etching than the alternate pattern under the same conditions. The tip size and height of Si nanotip structures determined by atomic force microscopy measurement were in the range of 50–80 and 450–750 nm, respectively.

Fe₃O₄–ZnWO₄ composite microspheres with magnetically recyclable photocatalytic performance have been firstly synthesised by a simple refluxing method under mild conditions. The as-prepared Fe₃O₄–ZnWO₄ composites show good photocatalytic efficiency in degradation of rhodamine B under UV light irradiation and can be recycled five times by magnetic separation without major loss of activity, the magnetic property of Fe₃O₄–ZnWO₄ sample has been studied also. Microspheres show potential use on dye degradation from the solution considering their magnetic recovery properties.

Thiyoglycolic acid-capped CdSe nanoparticles have been synthesised at 273–279 K. A comparative study on the structural and optical characteristics of the as-synthesised and annealed samples is done using state-of-the art instruments and software. Based on these studies here the authors report a colossal change in crystallinity, particle size and red shift in the absorption spectra upon annealing. Lattice strain is also found to increase by 18.77% upon annealing. Excitation wavelength-dependent photoluminescence with giant Stokes shift and narrow full-width at half-maxima of both the samples is also reported, which may be useful for device application.

Biomaterials is a term used to indicate materials that constitute parts of medical implants, extracorporeal devices, and disposables that have been utilised in medicine, surgery, dentistry and veterinary medicine as well as in every aspect of patient health care. Ceramics biomaterials are used as components of hip implants, dental implants, middle ear implants and heart valves. Porous or particulate calcium phosphate ceramic materials such as tricalcium phosphate (TCP) have proved successful for resorbable hard tissue replacements when low loads are applied to the material. The aim of the present work was to evaluate the biological characteristics of the biomaterial developed. Interactions of TCP with polyacrylate polymers in aqueous dispersions were characterised using X-ray diffraction, Fourier transform infrared spectroscopy, pH determination and viscosity measurements.

A report is presented on a new multi-mode nanofabrication method that uses a compliant conductive atomic force microscope (AFM) probe for both AFM and scanning tunnelling microscope (STM) operation and it is demonstrated that these modes can be switched ‘on-the-fly’ during the measurement or fabrication of nanostructures. The authors oxidised Ti with the same conductive AFM probe in AFM and STM modes, alternately in a continuous writing step. An in-plane Ti–TiO_x–Ti junction was fabricated by combining AFM and STM modes and electrically characterised by taking current images in conductive AFM mode. After measurement, additional features were written to increase the electrical isolation, thus realising in situ nanoscale modification.

In this reported work, a microfluidic-based fluid electrokinetic force has been used for surface plasmon resonance or surface plasmon resonance image (SPRI) detection. In this device, a modified rectangular microarray of Au instead of previous reported square or circular gold segments was designed and microfabricated with gold segment geometries and characterised by surface morphology studies. A voltage drop of maximal 400 V/cm was applied without gold erosion to drive fluorescein isothiocyanate isomer I in a high-conductivity medium on the bare gold surface layer, enabling SPRI detection.

The quartz double-ended tuning fork (DETF) resonator is well known to be sensitive to longitudinal force and is widely used as the sensing element in modern accelerometer, force and pressure sensors. The quartz DETF resonator works in-plane, with anti-phase flexural mode vibration, which is driven into oscillation by internal strains created by AC voltages applied to electrode patterns on the beams. The DETF vibration modes and vibration characteristics are determined by the electrode pattern and its electromechanical coupling efficiency. Presented are three kinds of electrode patterns for different applications, and the effect of electrode patterns on the vibration performances are investigated experimentally. With the fundamental frequency at 65 KHz, the DETF resonator is designed and fabricated using the wet etching-based quartz MEMS technique. The vibration characteristics including Q-value, and equivalent parameters, are evaluated using a 4294 A impedance analyser. Experimental results demonstrated that the vibration characteristics of quartz DETFs are affected by the electrode patterns including pattern location and widths. These results are expected to be useful for designing quartz DETF based devices.

Compact equivalent circuit models for single-walled carbon nanotube (SWCNT) bundles are described, and the performance of SWCNT bundle interconnects is evaluated and compared with traditional Cu interconnects at different interconnect levels for through-silicon-via-based three-dimensional integration. It is shown that at local level, carbon nanotube bundle interconnects exhibit lower signal delay and smaller optimal wire size. At intermediate and global levels, delay improvement becomes more significant with technology scaling and increasing wire lengths. For 1 mm intermediate and 10 mm global level interconnects, the delay of SWCNT bundles can reach 45.49 and 51.84% of that of Cu wires, respectively.