Proceedings of the Institution of Mechanical Engineers,Part N: Journal of Nanomaterials,Nanoengineering and Nanosystems

Generally, two spiral tool path generation methods are applied to ultra-precision three-axis turning of off-axis convex ellipsoidal surface, which are tool path generating by revolving around the axis of convex ellipsoidal surface and revolving around the axis of cylindrical surface. In this article, two different computed results of spiral tool path generation for off-axis convex ellipsoidal surface are analyzed, and several key technologies during tool path generation are analyzed in theory. The general procedure of generating the precision tool trajectory is also presented. The characteristics of two different turning trajectories for the surface manufacturing are compared and studied in some typical aspects in the end. The studies show that each of the two different tool path generation methods has its own suitable work environment, and a reasonable method should be chosen according to the processing requirement and work environment during the process of single-point diamond turning. The analysis and argument presented provide an effective choice of the accurate spiral tool path generation method in ultra-precision manufacturing of the off-axis convex ellipsoidal surface, and the method can be used in the accurate spiral tool path choice of any kind of off-axis surface.

In this research, Ni–P/nano-SiC composite coatings were prepared on wood surface by simple electroless plating approach. The flatness, porosity, and crystallinity of Ni–P/nano-SiC composite coatings were investigated. The flatness and porosity of the composite coatings enhanced with the increase in nano-SiC content of the coatings, and the composite coatings were obtained within the range of 0.5–1.5 g (1.8 g/L) nano-SiC in the solution bath. The full width at half maximum values of Ni X-ray diffraction peaks in the composite coatings broadened and strengthened with the increment of nano-SiC content in the coatings, which triggered preferred growth direction of diffraction peaks. The composite structure was characterized with scanning electron microscopy images. The uniformity of particles in the composite coatings could be improved obviously with the increase in the nano-SiC content of the coatings because an amorphous phase of SiC hindered the movement of dislocations and declined the size of Ni–P crystallite. Besides, the flatness, porosity, and crystallinity of composite coatings depended on the P content in the composite coatings. P content can be decreased by increasing SiC content of plating solutions. The flatness, porosity, crystallinity, and wear resistance of composite coatings exhibited excellent properties as the content of nano-SiC in the composite coatings reached 1.0 g (1.8 g/L).

A passive wireless pressure sensor based on low-temperature co-fired ceramic was investigated. The sensor is equivalent to a LC resonant circuit, which has a planar spiral inductor and an interdigital capacitor electrically connected. The inductor and capacitor are fabricated by screen printing technology. The working principle of the sensor is based on the pressure-sensitive resonant frequency of the LC circuit. Wireless detection can be realized by electromagnetic coupling with two inductor coils. The results show that the resonant frequency of sensor decreases with the increase in pressure, and sensitivity of the sensor is about 412.32 kHz/bar.

The influence of gravity on mass transport and micro direct methanol fuel cell performance is presented in this article. A multi-physics three-dimensional model calculated by COMSOL Multiphysics is established. The results show that gravity significantly affects the distribution of pressure and methanol concentration. To verify the simulation, a self-breathing transparent micro direct methanol fuel cell with horizontal orientation and vertical orientation is designed, fabricated and tested. The polarization curves of horizontal orientation exhibit the best performance with the power density of 25.57 mW cm⁻². Moreover, the cell placed with horizontal orientation exhibits faster CO₂ emission velocity than that of the cell with vertical orientation.

Piezoelectric inchworm actuators have a wide application in the field of nano-positioning and ultra-precision detecting instruments. Ultra-precision positioning equipments are urgently needed in the field of precision optics. A new piezoelectric linear actuator, based on inchworm motion principle, with a symmetry lever displacement amplification mechanism has been designed in this article. The whole structure adopts uniaxial-type double-notch right circular flexible hinge as its main hinges, which offers the driving part a larger displacement and makes clamping part have enough clamping force at the same time. High-precision cross roller guide ways are utilized to improve the positioning accuracy of the actuator. Both theoretical analysis and finite element analysis of clamping mechanism and driving mechanism have been carried out. An experimental test platform has been built, and a controlling program of the actuator is compiled by LabVIEW. The experimental results show that the working stroke of the actuator is ± 25 mm, resolution is 60 nm, the clamping force is 17 N, and the bearing capacity is 11 N; the actuator has a highest speed of 1.259 mm/s at the driving voltage 150 V.

Based on strain gradient theory with surface effect, this article discusses magneto-vibration of coupled double-layered visco-elastic graphene sheet systems embedded on elastic foundation. Graphene sheets were placed in uniform magnetic field and coupled with each other by an enclosing visco-Pasternak medium. Considering the Kirchhoff plate theory and Kelvin–Voigt model, the governing equation is derived using Hamilton’s principle. The equation is solved analytically to obtain the frequency of the coupled system. The parametric study is thoroughly performed, concentrating on the series effects of a magnetic field, visco-elastic damping structure coefficient, aspect ratio, surface layer, visco-Pasternak elastic medium, shear modulus, and mode number. In this system, in-phase and out-of-phase vibrations are investigated. The numerical results of this article show a perfect correspondence with those of the previous researches. The effect of magnetic field on the vibration of graphene sheet with different Winkler coefficients is exposed. Results from the model demonstrate that the magnetic field increases the natural frequencies.

Static and continuous-flow micro-gap reactors have been designed for the sterilization of bacteria. Their performances were verified using some pulsed electric fields. Several parameters such as electric field strength, pulse number and width, as well as flow rate, which may impact the sterilization effect, have been experimentally evaluated on these devices. Experimental results showed that the strength and width of pulses had significant impacts on the sterilization. Stronger and wider pulses favored the sterilization. More pulses could also achieve better sterilization effect. Continuous-flow manipulation contributed to realize high-efficiency sterilization. However, flow rate should be lower than a critical value. Higher flow rate may reduce the residence time in the reactor and harm the sterilization effect. Micro-gap reactor between the two parallel plate electrodes can contain more solution and the sample can be manipulated in a continuous way to realize higher sterilization throughput, but it is sometimes difficult to form even gap between these plate electrodes. Rough surface or burrs on these electrodes may induce discharge and limit the electric field strength. Some coatings on their surface may decrease the discharge, but they also undermine the electric field.

The objective of this article is to simulate a piezoelectric cantilever beam generator with power harvesting from ambient vibration energy. This power device will act as the electrical energy supply of a micro-system, which can be used in inaccessible situations, to eliminate dependence on batteries. Optimization of the micro-silicon-based piezoelectric cantilever parameters was achieved by determining the most advantageous dimensions for the piezoelectric generator, while varying the beam length, width, thickness, proof mass weight and so on. The program also made sure that the piezoelectric cantilever beam structure’s natural frequency is equal to the desired input frequency from the ambient exciting vibration. In addition, a prototype miniature generator was fabricated with bulk silicon combined with etching.

K₂Ti₆O₁₃ nanowires are excellent inorganic nanomaterials, which have high value and huge potential use in many fields. However, the biocompatibility of K₂Ti₆O₁₃ nanowires will be directly related to its application. But the quantity of its hemocompatibility reports is limited. In this study, K₂Ti₆O₁₃ nanowires were first synthesized by sol–gel/hydrothermal combined method. In view of its biosafety, the hemocompatibility of the novel nanomaterial was investigated by a hemolysis test. Fresh whole blood was drawn by venipuncture from a healthy human volunteer. The absorbance of free hemoglobin in the clear supernatant of the blood mixtures in contact with the test, positive and negative control groups was measured by ultraviolet–visible spectrophotometer for evaluating the hemolysis ratio. The hemolysis ratio of the test group is far lower than the standard of 5%. And the results indicate that the novel material has no hemolytic effect and has application prospects in the fields of biomedicine and biomaterials.