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This article proposes a low cross-axis sensitivity resonant MEMS(Micro-Electro-Mechanical Systems) accelerometer that is optimized based on the BP and NSGA-II algorithms. When resonant accelerometers are used in seismic monitoring, automotive safety systems, and navigation applications, high immunity and low cross-axis sensitivity are required. To improve the high immunity of the accelerometer, a coupling structure is introduced. This structure effectively separates the symmetric and antisymmetric mode frequencies of the DETF resonator and prevents mode coupling. To obtain higher detection accuracy and low cross-axis sensitivity, a decoupling structure is introduced. To find the optimal dimensional parameters of the decoupled structure, the BP and NSGA-II algorithms are used to optimize the dimensional parameters of the decoupled structure. The optimized decoupled structure has an axial stiffness of 6032.21 N/m and a transverse stiffness of 6.29 N/m. The finite element analysis results show that the sensitivity of the accelerometer is 59.1 Hz/g (Y-axis) and 59 Hz/g (X-axis). Cross-axis sensitivity is 0.508% (Y-axis) and 0.339% (X-axis), which is significantly lower than most resonant accelerometers. The coupling structure and optimization method proposed in this paper provide a new solution for designing resonant accelerometers with high interference immunity and low cross-axis sensitivity. [ABSTRACT FROM AUTHOR]

With the continuous progress of aerospace, military technology, and marine development, the MEMS resonance pressure sensor puts forward the requirements of not only a wide range but also high sensitivity. However, traditional resonators are hardly compatible with both. In response, we propose a new sensor structure. By arranging the resonant beam and the sensitive diaphragm vertically in space, the new structure improves the rigidity of the diaphragm without changing the thickness of the diaphragm and achieves the purpose of increasing the range without affecting the sensitivity. To find the optimal structural parameters for the sensor sensitivity and range, and to prevent the effects of modal disturbances, we propose a multi-objective optimization design scheme based on the BP and NSGA-II algorithms. The optimization of the structure parameters not only improved the sensitivity but also increased the interference frequency to solve the issue of mode interference. The optimized structure achieves a sensitivity and range of 4.23 Hz/kPa and 1–10 MPa, respectively. Its linear influence factor is 38.07, significantly higher than that of most resonant pressure sensors. The structural and algorithmic optimizations proposed in this paper provide a new method for designing resonant pressure sensors compatible with a wide range and high sensitivity. [ABSTRACT FROM AUTHOR]

AlSi10Mg has a good forming ability and has been widely accepted as an optimal material for selective laser melting (SLM). However, the strength and elongation of unmodified AlSi10Mg are insufficient, which limits its application in the space industry. In this paper, yttrium oxide (Y2O3) nanoparticles modified AlSi10Mg composites that were manufactured using SLM. The effects of Y2O3 nanoparticles (0~2 wt.% addition) on the microstructure and mechanical properties of AlSi10Mg alloys were investigated. An ultimate tensile strength of 500.3 MPa, a yield strength of 322.3 MPa, an elongation of 9.7%, a good friction coefficient of 0.43, and a wear rate of (3.40 ± 0.09) ×10−4 mm3·N−1·m−1 were obtained with the addition of 0.5 wt.% Y2O3 nanoparticles, and all these parameters were higher than those of the SLMed AlSi10Mg alloy. The microhardness of the composite with 1.0 wt.% Y2O3 reached 145.6 HV0.1, which is an increase of approximately 22% compared to the unreinforced AlSi10Mg. The improvement of tensile properties can mainly be attributed to Orowan strengthening, fine grain strengthening, and load-bearing strengthening. The results show that adding an appropriate amount of Y2O3 nanoparticles can significantly improve the properties of the SLMed AlSi10Mg alloy. [ABSTRACT FROM AUTHOR]

Quartz glass shows superior physicochemical properties and is used in modern high technology. Due to its hard and brittle characteristics, traditional polishing slurry mostly uses strong acid, strong alkali, and potent corrosive additives, which cause environmental pollution. Furthermore, the degree of damage reduces service performance of the parts due to the excessive corrosion. Therefore, a novel quartz glass green and efficient non-damaging chemical mechanical polishing slurry was developed, consisting of cerium oxide (CeO2), Lanthanum oxyfluoride (LaOF), potassium pyrophosphate (K4P2O7), sodium N-lauroyl sarcosinate (SNLS), and sodium polyacrylate (PAAS). Among them, LaOF abrasive showed hexahedral morphology, which increased the cutting sites and uniformed the load. The polishing slurry was maintained by two anionic dispersants, namely SNLS and PAAS, to maintain the suspension stability of the slurry, which makes the abrasive in the slurry have a more uniform particle size and a smoother sample surface after polishing. After the orthogonal test, a surface roughness (Sa) of 0.23 nm was obtained in the range of 50 × 50 μm2, which was lower than the current industry rating of 0.9 nm, and obtained a material removal rate (MRR) of 530.52 nm/min. [ABSTRACT FROM AUTHOR]

The x-SnO2/α-Fe2O3 (x = 0.04, 0.07, and 0.1) heterogeneous composites were successfully prepared via a two-step solvothermal method. These composites were systematically characterized by the X-ray diffraction technique, field emission scanning electron microscopy, an energy dispersive spectrometer, X-ray photoelectron spectroscopy and a UV–visible spectrometer. It was found that SnO2 nanoparticles were uniformly decorated on the surface of α-Fe2O3 particles in these heterogeneous composites. A comparative study of methylene blue (MB) photodegradation by α-Fe2O3 and x-SnO2/α-Fe2O3 composites was carried out. All x-SnO2/α-Fe2O3 composites showed higher MB photodegradation efficiency than α-Fe2O3. When x = 0.07, the MB photodegradation efficiency can reach 97% in 60 min. Meanwhile, the first-order kinetic studies demonstrated that the optimal rate constant of 0.07-SnO2/α-Fe2O3 composite was 0.0537 min−1, while that of pure α-Fe2O3 was only 0.0191 min−1. The catalytic mechanism of MB photodegradation by SnO2/α-Fe2O3 was examined. The SnO2 can act as a sink and help the effective transfer of photo-generated electrons for decomposing hydrogen peroxide (H2O2) into active radicals. This work can provide a new insight into the catalytic mechanism of the photo-Fenton process. [ABSTRACT FROM AUTHOR]

A novel structure of a metal/dielectric/metal (Ag/SiO2SiO2/Ag) sandwich nanocrescent has been proposed and studied. We make a detailed numerical analysis on the extinction efficiency and LSPR property of the sandwich nanocrescent by using the finite difference time domain (FDTD) method. It clearly demonstrates that a comparable field enhancement can be achieved by varying the thickness of the SiO2SiO2 layer at different incident polarizations. Excited in the Y-polarization, the maximum electric field enhancement factor reaches 600 at the peak wavelength 1108.9 nm, which is six times higher than previous reported single layer nanocrescent. The refractive index sensitivity of this new sandwich nanocrescent is 375.5 nm/RIU (refractive index unit). The structure is shown to produce a high local field enhancement as well as wide plasmon resonance tunabilities. Besides, compared with adjusting the shape and size of the single layer nanocrescent structure, it is much more convenient and easier to change the thickness of the sandwich nanocrescent. Due to its excellent properties, this structure is very suitable for LSPR and SERS nanosensing substrate. [ABSTRACT FROM PUBLISHER]

This paper presents a microfluidic device that geometrically constrains the development of individual Dictyostelium discoideum cells into multicellular organisms (slugs). A microchip for the stimuli-directed migration of slugs is also presented. To demonstrate the formation of slugs in a predetermined shape, a microchip is designed to confine the slugs in the vertical direction. In the microchip, sufficient oxygen is supplied to the cells via a membrane, allowing the formation and adaptation of slugs to the shape of the channel. In addition, the manipulation of slug migration direction in a microchip via external stimuli, such as light and temperature gradients, that induce phototaxis and thermotaxis of slugs, respectively, is demonstrated. To direct slug migration with external stimuli, an optical fiber is used for phototaxis and an electrical wire heater is used for thermotaxis. Experimental results show slug formation in a predefined geometry in the microchip, suggesting that this chip is potentially useful for understanding the relationship between the shape and function of cells or tissue. The controlled migration of slugs demonstrated in the microchips can potentially be employed in biologically based microactuators or microrobots.