An enzyme-free glucose electrochemical sensor with high sensitivity and selectivity is highly attractive. In this work, an enzyme-free glucose sensor with Cu₂O hollow microspheres (Cu₂O HMs) was prepared via hydrothermal method. The glucose sensor constructed by the prepared Cu₂O HM structure exhibited a low detection limit of 0.13 μM, a high sensitivity of 277.1 μA/mM cm², and the wide linear ranges of 0.05–1.5 and 1.5–6.0 mM. Furthermore, anti-interference tests indicated that the prepared sensor exhibited good selectivity for glucose and practical application in human serum. The Cu₂O sensor has great application potential in the development of enzyme-free glucose sensor.

UiO-66 nanoparticles (NPs) were prepared by the solvothermal method using deep eutectic solvents (DESs) and compared to those prepared using the traditional solvent, dimethylformamide. A mixture of choline chloride:glycerol with a molar ratio of 1:2 was used as a green solvent to prepare the NPs. SEM, a Fourier transform infrared spectrometer, zeta potential, N₂ adsorption/desorption, and surface area characterisations were used to characterise the NPs. Results showed that the NPs formed in the DES had a smaller size but the lower surface area and functionalised with new chemical groups due to the DES effect. Also, the modified metal–organic frameworks surface area increased by increasing the incubation time but decreased by increasing the temperature.

An 80-mg double piezo-actuated insect-inspired flapping-wing robot is presented in this Letter. With the design of the two piezoelectric actuators placed back to back, each wing of this robot is independently driven and controlled, giving this robot the ability to achieve asymmetric flapping of the two wings to generate torques for steering. The piezoelectric actuators are designed with electrical insulation and structural reinforcement to improve the reliability under high-voltage and high-frequency drive mode. Fibre directions of each component of the robot are reasonably designed to enhance strength and stiffness. The average lift generated by the robot is measured by a customised lift measurement system found to be proportional to the square of the input voltage amplitude. The three steering torques generated by the robot are measured separately by a customised lift measurement system. Each steering torque can only be linearly modulated by its specific control variable of the input voltages. With a total weight of 80 mg and a wingspan of 3.5 cm, this robot can generate sufficient lift to take off and independently modulate all three steering torques with good decoupling, which is vital for the further controlled flight.

Wet anisotropic etching of Si{100} results in micro-pyramids/hillocks bounded by four {111} planes. These kinds of geometrical structures are needed to reduce the front surface reflectance from silicon by taking multiple internal reflections of the incident ray and thus increase the efficiency of the solar cells. In this work, surface texturing of Si{100} is performed at different temperatures in a very low concentration CMOS compatible tetramethylammonium hydroxide (TMAH) without using any additive and agitation. The present research is aimed to significantly reduce the etching time in an extremely low concentration TMAH to texture the silicon surface for obtaining the lowest possible reflectance. Etching temperature is varied from 80 to 95°C with a step of 5°C. For each temperature, the etching time is also varied from 5 to 40 min with an interval of 5 min, whereas etching concentration is made a fix to 0.5 wt%. Surface morphology with dense and uniform pyramidal structures is achieved on the silicon samples etched at 85°C for 25 min. These samples provide the average solar weighted reflectance (R _sw) of around 10% and the lowest reflectance of 6.7% at 790 nm.

Compared with common TiO₂ powder, TiO₂ nanotubes can exhibit better catalytic performance for their high specific surface area. By using hydrogen TiO₂ nanotubes synthesised via the hydrothermal process as carriers, carbon and platinum co-modified TiO₂ nanotubes (C-Pt/TiO₂NTs) were prepared via impregnation–photoreduction method in this study. X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and infrared spectrum were used to characterise the structure and composition of the prepared samples. Their catalytic activities for degrading methyl orange under ultraviolet (UV) illumination and simulated sunlight were evaluated. The influences and mechanism of dopants and their contents on the catalysts’ activity were investigated. Obtained results indicated that the modification can improve the photocatalytic activity of TiO₂ nanotubes under both UV light and simulated sunlight. Among them, C-Pt/TiO₂NTs with 0.5 wt% Pt exhibited the best performance.

A green and natural biomass carbon with hollow structure was first reported derived from waste makeup cotton, which was prepared by facile pyrolysis and carbonisation in the nitrogen-filled vacuum tube furnace. Utilised as lithium-ion batteries (LIBs) anode materials, the hollow structure exhibits superior cycling and rate performance. At the current density of 100 mA g⁻¹, it demonstrates a reversible capacity of 340 mAh g⁻¹ with the Coulombic efficiency of 58.8%, and the reversible capacity gradually increases to 450 mAh g⁻¹ at 300 cycles, displaying long cycling stability. Even at a higher current density of 500 mA g⁻¹, the capacity can be maintained around 245 mAh g⁻¹ after 150 cycles. Moreover, the hollow carbon exhibits excellent rate capability (222 mAh g⁻¹ at an ultrahigh rate of 2000 mA g⁻¹). This enhanced property can be attributed to its special hollow structure, which could provide fast lithium ions and electrons transfer path to facilitate the electrochemical reaction. The authors believe this work could help to design new carbon materials with green and environmental protection as anode materials for LIBs.

Neotame is an artificial sweetener with increasing consumption in recent years, excessive intake of it may bring potential health risk. In this work, a rapid method was developed to detect neotame in instant grain beverages, which was based on surface-enhanced Raman scattering (SERS) technique and filter paper-based silver nanoparticles (AgNPs@FP) substrates. The designed substrate exhibits good SERS activity with an enhancement factor of 10⁵ because of the synergistic effect of the concentrated silver nanoparticles and filter paper. Meanwhile, the stability and repeatability of this fabricated substrate have been investigated with the relative standard deviation of 6.1%. In addition, it shows an excellent linear relationship (R ² = 0.997) between the SERS signal and the logarithm concentration of neotame with a wide concentration range (0.05–5 g/kg) in the quantitative analysis. The limit of detection of neotame can be as low as 0.01 g/kg in instant grain beverages, which is below the maximum allowable addition level for neotame in instant grain beverages set in China (GB2760-2014, 0.16 g/kg). The proposed method has great potential for the identification and quantification of neotame in food safety applications with high sensitivity.

Functionalised multi-walled carbon nanotubes (MWCNTs) are exclusively used in antibacterial activity due to their high aspect ratio and surface penetration characteristics. This study reports the synthesis of piperazine and dopamine functionalised MWCNTs to investigate antibacterial activity against strains like Staphylococcus aureus and Micrococcus luteus. MWCNTs were activated through acid oxidation and then refluxed at 75°C for 10 and 8 h in the presence of piperazine and dopamine, respectively. The functionalised MWCNTs were characterised by scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction and Raman spectroscopy. Moreover, functionalised MWCNTs were subjected to zone inhibition assay on agar plates. Results revealed the significant antibacterial activity against various bacteria up to 50%. Similarly, it was observed that the effect of different solvents, such as dimethyl formamide (DMF) and dimethyl sulfoxide (DMSO) was non-prevalent to the bacterial zone of inhibition. Such facile nano-modifications provide passage to nano-antibacterials for advanced studies.

By an in-situ seeding synthetic route, with biocompatible reagents being used, walnut kernel-like Ag nanostructures (Ag nanowalnuts) composed of nanoplates were fabricated. The in-situ formation of seeds and introduction of complex [Ag₃(C₆H₅O₇)_n+1]³ⁿ⁻were indispensable steps for this kind of self-assembled nanostructure. The size of Ag nanowalnuts was in the range of 200–400 nm and the thickness of a single nanoplate was about 30 nm. The morphology of nanoplates was of variety, and their surface was bumpy. Such Ag nanostructures with rough surface and high curvature provided plenty of ‘hot spots’ on a single particle for surface-enhanced Raman scattering (SERS) enhancement. Experimental results indicated that the Ag nanowalnuts offered great surface enhancement for 4-mercaptobenzoic acid and malachite green molecules. The limit of detection was low to 10⁻¹⁰ and 10⁻⁸ M, respectively.

The combination of microstructures and nanostructures has broad application prospects. However, most existing methods are oriented to fabricating microstructures and nanostructures separately, and the fabrication of nanostructures on a microstructured surface at the wafer level is rarely studied. In this work, a new method of fabricating large-area high aspect ratio nano-cylinders on micro-pillars based on a colloidal crystal mask is proposed. An experimental device for stripping and draining was designed to create a polystyrene colloidal crystal mask. Together with reactive-ion etching and metal-assisted chemical etching, high aspect ratio nano-cylinders on micro-pillars with controllable size were obtained on a 4-inch silicon wafer. Wetting tests were performed on four groups of fabricated structures of different sizes, and the results showed that all samples were superhydrophobic. Thus, a method for fabricating uniform, size-controllable, large-area high aspect ratio nano-cylinders on micro-pillars with great potential as a superhydrophobic engineering material is proposed.

Mesoporous nanoparticles have a larger surface area and therefore, suitable for dye-sensitised solar cells and photocatalytic applications. This Letter presents the analysis of solvothermal derived as-prepared TiO₂ and doped TiO₂ nanocrystals by utilising acetone as the solvent. The as-prepared and doped TiO₂ nanoparticles endorsed the presence of anatase phase along with the slightly deviated diffraction peaks with the reduced crystallite size as a result of doping. Surface morphology analyses evidenced the mesoporous microspheres of nanoparticles, whereas the stoichiometry study exhibited the elementary peaks in the as-prepared and doped samples. The estimated optical bandgaps are found to be 2.68, 2.92, 2.48 and 2.88 eV in accordance with the doped TiO₂ with copper, tin, barium and zinc–magnesium as compared to 3.16 eV of TiO₂. Doped samples evidenced the enhanced scattering capability, whereas tin and zinc–magnesium co-doped samples demonstrated the highest diffuse reflectance in a broad wavelength range from 550 to 800 nm.

Various sizes and morphologies of noble metal/zinc oxide hybrid materials have promising applications in surface-enhanced Raman scattering (SERS). Generally, organic agents used during the synthesis of metal nanoparticles will inexorably induce organic pollution on the surface of SERS substrate, resulting in a negative effect on detection sensitivity. Herein, a stable and clean 3D flower-like ZnO/Ag hierarchical microstructure SERS substrate was designed and fabricated via a simple photocatalytic method. This synthetic strategy does not involve usage of any organic agents, which ensures the cleanness and free of impurities interferences. As anticipated, the as-fabricated 3D flower-like ZnO/Ag SERS substrates with high surface-to-volume ratio increased numerous hot spots, and exhibited excellent detection sensitivity to Rhodamine 6G. A linear relationship between the Raman intensity and the concentration of Rhodamine 6G ranging from 10⁻¹¹ to 10⁻⁴ M was realised. This work demonstrated a performance-enhanced SERS sensor based on microflower-like ZnO@Ag hybrids, which provides a potential method to develop highly sensitive and stable SERS sensor for organic molecules detection.

The pure rutile and Ag-rutile nanomaterials were synthesised using sol–gel route and the effect of Ag concentration on the composite photocatalyst activity was investigated. The results show that the Ag⁰ particles are deposited on the rutile surface, forming Ag-rutile heterojunctions. The high concentration of Ag is beneficial to inhibit the recombination of electrons and holes, meanwhile, excessive Ag particles will hinder the absorption of light source and adsorption of RhB molecules. Therefore, 2% of Ag rutile exhibits the highest photocatalytic activity.

The study presents the design of a magnetic nanosystem functionalised with Escherichia coli for bacteriophage isolation. The chitosan-coated nanoparticles (C-MNP) were synthesised by coprecipitation, then functionalised with E. coli cells. Different concentrations of C-MNP and incubation times were tested. The immobilisation kinetics and adsorption isotherm were studied. The kinetics was described with the pseudo-stationary state after 30 min. The isotherm was linearized in the Freundlich model. Thermogravimetric analysis verified the functionalisation of C-MNP with E. coli. The complex was used for the extraction of coliphage, for the analysis of the effect of time and salt concentration on phage desorption, and phage extractions with the reuse of the magnetic nanosystem. Compared with traditional methods, an increase in the phage titre collected with the nanocomplex was achieved. The obtained results suggest that C-MNP/E. coli nanosystem can be used at least three cycles for the phage extraction. The release of the phages from the nanosystem was sensitive to the salt concentration. The use of a designed nano-bio complex allowed a rapid and efficient separation of the phages from the water sample under the application of an external magnetic field, and with the possibility of reusing the magnetic complex.

Over the past two decades, the manipulation of nanoparticles has attracted increasing attention. This process provides essential information about tribology, which is of great significance for the exploration of the origin of friction. However, the motion state of the nanoparticles during this process must first be determined. Furthermore, since the nanoparticles could slide, roll, or spin when manipulated by the probe of the atomic force microscope, it was difficult to distinguish whether the force measured in the experiments denoted sliding or rolling friction. In this Letter, considerable manipulation and friction measurement experiments were performed, while the theoretical rolling and sliding friction were calculated using the Double-Hertz model. Furthermore, by comparing the theoretical calculations and experimental results, the motion state of the nanoparticle could be determined. Additionally, it was found that the critical rolling distance, which is essential for calculating rolling friction, decreases as the particle size increases.

To the best of the authors’ knowledge, this Letter reports and validates for the first time an on-chip reseTable test method that can be used to in-situ evaluate the impact reliability of a process-related silicon microbeam. A test structure integrating impact generating device, test samples, and a lock module is proposed to evaluate the impact-resistant reliability of the process-related microbeam samples with only a common optical microscope and probe station in the fabrication line. A calculation model that uses the LS-Dyna module in the finite-element commercial software ANSYS to process the test results is proposed to obtain the numerical parameters of the impact resistance reliability of the microbeam specimen. The test structure can be manufactured using a variety of mainstream MEMS silicon processes, so it can characterise the impact reliability of silicon microbeam structures under various processes. The above three parts constitute a self-aligned, low-cost test method with automation potential, which can be used for large-scale characterisation of the impact resistance reliability of silicon microbeam structures on the fabrication line. Finally, beam specimens under three different process conditions were manufactured and successfully evaluated using this test method, which verified the rationality of this method.

In this Letter, new chrysanthemum-shaped micrometre calcium carbonate was prepared by using CaCl₂ aqueous solution + NH₃H₂O + CTAB + n-butanol + n-hexane inverse microemulsion system. Scanning electron microscope, X-ray powder diffraction, and Fourier transform infrared spectroscopy were used to characterise the morphology and structure of the micron calcium carbonate. Further, the formation mechanism of chrysanthemum-shaped micron calcium carbonate was discussed.

This Letter reports the synthesis of nanoceramic composite ZnAl₂O₄TiO₂ by using a cost-effective and straight forward sol–gel route. X-ray diffraction (XRD) showed the ZnAl₂O₄ cubic structure along with the mixed anatase- and rutile-phases of TiO₂. Rietveld refinement is performed using XRD pattern to study the structural parameters. Raman investigation endorsed the corresponding vibration peaks of TiO₂ and ZnO. Field-emission scanning electron microscopy evidenced the agglomerated spherical nanoparticles. Energy-dispersive spectroscopy analysis demonstrated the elementary peaks of Zn, Al, and Ti at 4.5, 1.5, and 1 eV, respectively. LCR measurement revealed the decreased dielectric permittivity with the rise in frequency and temperature. This dielectric characteristic is attributed to the dipole movement of the charge carriers. Furthermore, the authors present the investigation of the conductivity and impedance of the prepared dielectric ceramic material.

Bismuth halide oxide with three halogen elements (P-BiOXs) catalyst was prepared by a facile precipitation method at room temperature only for 30 min. Several measurement technologies were employed to characterise the structures and morphologies of the obtained samples. Coloured Rhodamine B (RhB), methyl orange (MO), methylene blue (MB) and colourless bisphenol A (BPA) were selected to evaluate the photocatalytic activity of the samples. The experimental results showed the P-BiOXs thin nanoplates exhibited the most excellent photocatalytic activity among the prepared samples for the degradation of MO under visible light illumination. More importantly, the catalyst P-BiOXs could effectively degradate RhB, MB and BPA. The P-BiOXs catalyst displayed good photocatalytic stability by the recycling tests. The highly efficient visible light catalytic properties of P-BiOXs could be due to the high specific surface area, enhanced light-harvesting ability, the suitable bandgap energy and the lower recombination rate of the photogenerated electrons and holes.

Accurate and meticulous measurement is an important prerequisite to obtain the real surface information of samples in atomic force microscopy (AFM). A severe problem is the frequent occurrence of measurement errors, which are mainly caused by the nonlinearity of the probe driver, the temperature drift of the system and the tip characteristics. The measurement errors caused by probe tip are the main source of errors in AFM nanoscale measurements. The shape and state of AFM tip will distort the AFM image from the actual sample morphology. If the information about the probe is known, the measurement error caused by the probe tip can be greatly reduced. In order to obtain accurate AFM images, a new method based on geometric measurement model and blind tip reconstruction is proposed to eliminate tip-sample convolution in the measurement of grating samples. The static and dynamic characteristics of the AFM tip are described by four parameters: cone angle, curvature radius, scanning inclination angle and mounting inclination angle. Finally, the feasibility and effectiveness of the new calibration method are verified by evaluating the image reconstruction quality. In conclusion, the proposed method can effectively reconstruct accurate AFM images of the grating.