This study presents an absolute-pressure capacitive vacuum sensor featuring an open-hole structure and a silicon–silicon–glass sandwich configuration for real-time dynamic measurements of minute variations in pressure. The vacuum-sealed cavity is fabricated using bonding technology, which effectively addresses the challenges of low bonding yields and high-vacuum packaging in conventional silicon–silicon bonding processes while extending the measurement range from 1 Pa to 84000 Pa. To validate the performance advantages of the proposed structure, silicon–silicon and silicon–silicon–glass sensors with identical dimensional parameters were simultaneously fabricated using MEMS (Micro-Electro-Mechanical Systems) technology and tested over the full (1~84000) Pa pressure range in a vacuum testing system. The experimental results demonstrate that the trends in the fabricated sensors’ capacitance closely match the simulation results, with the silicon–silicon–glass structure achieving a maximum sensitivity of 20.387 fF/Pa and resolution of 1 Pa in the low-pressure range of (1~1000) Pa. Compared to the silicon–silicon counterpart with identical dimensions, the proposed structure exhibits approximately 29.5% and 66.7% improvements in sensitivity and resolution, respectively, while significantly enhancing vacuum packaging performance. The maximum measurement error remained below 0.27% throughout the 45-day test, confirming its excellent reliability for vacuum measurement applications.

This study employed direct current magnetron co-sputtering to deposit thin films with Nb/V atomic ratios of 1:1 and 3:7 using NbV alloy targets, and systematically examined the effect of composition on the structure and properties of the films. The results reveal that the film with a 1:1 composition tends to develop coarse columnar crystals during deposition ， which leads to a significant increase in specific surface area. The dynamic hydrogen adsorption testing was conducted by constant pressure method, and the results showed that its initial hydrogen adsorption rate and saturation adsorption capacity are 2.5 times and 1.5 times higher, respectively, than those of the 3:7 composition films at activation temperature of 450°C. The comparison with our previously reported ZrCoRE film, the NbV film shows a significant reduction in activation temperature by roughly 100 °C under the same conditions. Analysis of surface roughness and residual stress further shows that the 1:1 composition film exhibits a surface morphology that is more suitable for gas adsorption and a lower overall stress level. This study confirms the potential of binary NbV alloys as high-performance absorber films with low activation temperatures and the performance can be improved by precise control of the Nb/V stoichiometric ratio.

Micro-electro-mechanical systems (MEMS) capacitance diaphragm gauges (CDGs) integrate complementary metal-oxide-semiconductor (CMOS) technology, providing low cost, low power consumption, and high integration. However, their accuracy is limited by leakage currents that reduce capacitance-to-digital conversion precision. To overcome these limitations, this study presents a high-precision capacitance-to-digital conversion circuit. The circuit adopts a continuous-time switched-capacitor architecture and incorporates a calibration module to suppress leakage current effects and improve conversion accuracy. Simulation results indicate that the effects of leakage currents and circuit mismatches are suppressed to approximately 24% of their original level by the proposed design. Experimental validation further confirms that the circuit extends the measurement range below 0.1 torr, maintaining a correlation coefficient of 0.999, improved repeatability, and a root mean square error (RMSE) of 0.024 torr under constant pressure. These results improve both the accuracy and stability of MEMS CDG and lay a robust foundation for their deployment in high-precision vacuum measurement.

The performance of vacuum packaged micro-electromechanical system (MEMS) devices is affected by the exfoliation of getter films, making it necessary to reduce film stress while improving the adsorption properties of the getter films. To this end, we investigated getter films structure in single- and double-layered configurations deposited on SiO2/Si substrates, such as ZrCoRE/SiO2/Si and ZrCoRE/Ti/SiO2/Si. The surface roughness and adsorption properties of the deposited getter films with single- or double-layered films were tested using a constant volume method and an atomic force microscope (AFM), respectively. The results showed that the microstructure of the films is columnar and influenced by the surface roughness of the substrate due to the atomic shadowing effect and low mobility of atoms. This kind of columnar structure increases the initial adsorption speed and adsorption quantity of ZrCoRE/Ti to H2 from 472.32 ml/s x cm2 and 89 Pa x ml/cm2 to 701.9 ml/s x cm2 and 104 Pa x ml/cm2. The residual stresses of the getter films were measured using techniques for surface analysis. The results showed that the residual stress of ZrCoRE getter films is realized by the substrate containing the Ti seed layer. We conducted long-term stability and repeatability analysis of two types of absorbent films placed in MEMS capacitance vacuum sensors with similar C-P curves. The results showed that the sensor with the double-layer ZrCoRE/Ti film performs significantly better than the sensor with the single-layer ZrCoRE film. Therefore, the Ti layer introduced in this article combines the functions of an absorber and an adhesive layer, effectively improving the gas absorption performance and reducing film stress, thereby reducing the risk of device failure.

High sensitivity is crucial for anisotropic magnetoresistive (AMR) sensors in industrial applications. In this paper, a high- sensitive AMR sensor based on magnetoresistive thin films with Ta/NiFe/Ta/Al four-layer structure is proposed and fabricated. Firstly, the structural parameters were optimized by finite element analysis. Secondly, thin film samples and AMR sensors were prepared. Through the analysis and characterization of reluctance change rate, hysteresis loop, x-ray diffraction and surface morphology and structure, the process parameters were optimized. Finally, the sensor was connected to the designed external circuit, and its technical parameters were tested in a magnetic field test system. The results show that the prepared AMR sensor performs well. It has a high sensitivity of 1.27 mV/V/Oe, a low bridge offset voltage of +/- 1.64 mV V-1, and a low temperature coefficient of sensitivity of -0.102%/degrees C. The results contribute to the future development of AMR magnetic field sensor chips.

A capacitance diaphragm gauge based on a glass-silicon-glass structure was designed to possessed two sealed reference cavities. Square pressure-sensing diaphragm with four corners chamfered was used as the sensitive element, and non-evaporation getter film was utilized to maintain the vacuum pressure in the reference cavities. The gauge with the size of 13×8×1.4 mm 3 was manufactured by micromachining technology and its performance was studied systematically. Measurement rang, sensitivity and long-term stability of the gauge were tested and analyzed. The experimental results indicated that the gauge had an operating range of 1 to 8.5×10 5 Pa, and it can be used to measure accurate vacuum pressure ranging from 1 to 1000 Pa with a high sensitivity. Moreover, the long-term tests demonstrated that the gauge was stable enough for absolute vacuum pressure measurement.

Miniaturization of sensors using micromachining technology is full of potential and challenges. A miniature capacitance diaphragm gauge for absolute vacuum measurement is developed in this work. Both theoretical calculation and simulation method are used to analyze the working principle of the pressure sensitive diaphragm in different pressure regions. During the manufacturing processes, a silicon block coated with non-evaporable getter films is used to protect the diaphragm and maintain the vacuum pressure of the reference cavity. The capacitance diaphragm gauge with an overall size of 8 x 10 x 1.4 mm(3) was successfully fabricated, and its vacuum metrologies in rough and medium vacuum regime were evaluated systematically. The lower measure-ment limit of the gauge is 0.1 Pa, its maximum and minimum sensitivities in the range of 0.1 Pa to 84 kPa are 10.96 and 0.16 fF/Pa, respectively. The repeatability and the hysteresis errors of the gauge are less than 1.3% and 5.3%.

基于微机电系统(MEMS)技术研制了一种新型电容薄膜真空计,结合测量电路,对真空计的整体性能进行了研究.结果表明,MEMS电容薄膜真空计具有良好的稳定性,测量范围为0.2～1050 Pa,分辨率为0.1 Pa,准确度达到0.1％FS.封装后的MEMS电容薄膜真空计质量为5.0 g,体积为4.1 cm3,整机功耗为2 W左右,具有质量轻、体积小、功耗低、成本低的特点,在空间应用以及工业生产应用中比传统的机械式电容薄膜真空计更具优势.

Due to the need of miniaturization and integration for pressure monitoring fields, micro-electromechanical system (MEMS) vacuum sensor has attracted increasing attentions. In this paper, a touch-mode MEMS capacitance vacuum sensor with a full range of (20-84000) Pa based on silicon bonding technology was designed in the absolute pressure type. The design principle of the MEMS capacitance vacuum sensor was demonstrated, and the pressure-sensing diaphragm deflection is analyzed by ANSYS. The MEMS capacitance vacuum sensor was fabricated by self-stopped etch technique based on boron-doped process. The structure morphology and chemical composition of the boron-doped pressure-sensitive diaphragm were characterized by atomic force microscope (AFM), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The capacitance-pressure (C-P) performance of touch-mode MEMS capacitance vacuum sensor was evaluated by the vacuum testing system. The testing results show that the C-P curve is characteristic of piecewise, and the touch stage is the main working stage of the MEMS capacitance vacuum sensor, in which the sensor has relatively high sensitivity with 60.76 fF/Pa.

MEMS vacuum gauges have received a great deal of attention in recent years. In this paper, a MEMS capacitance diaphragm vacuum gauge with high sensitivity and wide range is designed for differential pressure measurement. A novel circular silicon diaphragm is used as the pressure-sensing diaphragm of the gauge. The diaphragm has a large radius-to-thickness ratio of 283 and works in touch mode. The design principle of the gauge is introduced in detail, and the finite element software is used for simulation analysis. Based on the techniques of microfabrication, a prototype of the gauge was fabricated, and its performances were investigated using a differential vacuum system. The results show that the MEMS capacitance diaphragm vacuum gauge, having good stability and repeatability, is capable to measure differential pressure from 0 Pa to atmospheric pressure. The capacitance-pressure curve is piecewise linear, with the maximum sensitivity of 26 fF/Pa in the low range and the minimum sensitivity of 0.8 fF/Pa in the high range.

In order to solve the problem of existing diagnostic methods for chronic gastritis which are complex and traumatic, a novel noninvasive method for diagnosis of chronic gastric based on e-nose and deep convolutional neural network is proposed. Firstly, in order to collect samples, a respiratory gas sampling device was established and the response curve of respiratory gas is generated. Then, a deep convolutional neural network for the diagnosis of chronic gastritis is proposed to recognize and classify the respiratory gas response curve. The DCNN model attained good results with accuracy, sensitivity, and specificity of 85.00%, 90.00%, and 80.00%, respectively, for chronic gastric prediction. The proposed method provides a new way for the clinical auxiliary diagnoses of chronic gastric.

The shape, size, and working state of the pressure-sensing elements are important factors to determine the pressure sensor performances. A touch mode micro-electro-mechanical-system (MEMS) capacitance diaphragm gauge with a circular silicon pressure-sensing diaphragm for vacuum pressure measurement is presented. The diaphragm is designed to work in touch mode, and its basic structure and working principle are introduced. The MEMS capacitance diaphragm gauge has been fabricated, packaged, and tested. The results show that the capacitance-pressure curve has the typical characteristics of touch mode, which is consistent with the original design. The gauge exhibits a good performance in the measurement range of 1 Pa to atmospheric pressure, and the maximum and the minimum sensitivities are 22.16 and 2.39 fF/Pa, respectively. Moreover, the piecewise linear fitting of the capacitance-pressure curve is analyzed.

This paper presents a touch mode MEMS capacitance diaphragm gauge for differential pressure measurement. The design principle of the gauge is demonstrated, then the diaphragm deflection and capacitance sensitivity are analyzed theoretically. Experimental work was carried out using a principle prototype, which has a square pressure-sensing diaphragm with large width-to-thickness ratio. The test results are consistent with the theoretical model for pressure from 1 Pa to 1000 Pa, and the capacitance-pressure curve of the gauge is near linear in three pressure sections and a maximum sensitivity of 135 fF/Pa is achieved in low pressure range. Moreover, high pressure test results ranging from 1000 Pa to atmospheric pressure indicate that the developed touch mode gauge has wide load range and good overload protection. (C) 2020 Elsevier B.V. All rights reserved.

提出了一种基于MEMS技术的差压式电容薄膜真空规设计方案.通过有限元分析软件建立了仿真模型,对感压薄膜尺寸和电极间距离进行了优化.根据优化结果,完成了真空规的研制和性能测试.测试结果表明,测量范围下限5 Pa,上限1000 Pa,灵敏度优于10 fF/Pa,测试曲线可以实现分段线性.

An absolute MEMS capacitance vacuum sensor with a full range of (1-1000) Pa has been designed, fabricated and tested. The working principle of the capacitance vacuum sensor is explained and its fabrication process is introduced. For obtaining high sensitivity, the sensor's pressure-sensing diaphragm with large width-to-thickness ratio is manufactured using the silicon-on-insulator (SOI). A silicon buffer block is adopted to improve the linearity of the sensor and prevent the pressure-sensing diaphragm from being damaged due to overload. The sensor is packaged by anodic bonding process in a certain high vacuum environment to form a sealed cavity, in which the vacuum degree is maintained by the non-evaporable getter (NEG) film deposited on the buffer block surface. The absolute pressure measurement of the packaged sensor has been performed with a vacuum measurement system. The tests results show that the capacitance-pressure curve is piecewise linear in the full range (1-1000) Pa. And the sensor exhibits high stability and reproducibility. The maximum sensitivity of the sensor is 33.03 fF/Pa, while the resolution can reach 0.5 Pa. Moreover, the temperature characteristic of the sensor has been evaluated, and it turns out that the effect of temperature on the sensor is quite small in a certain temperature range. [2020-0276]

Thermal conductivity is an important quantity which represents the characteristic of Vacuum Insulation Panel’s (VIP’s) performance. Precise measurement of thermal conductivity provides better quality assurance for the users. In this paper, we presented a novel embedded sensor method to measure the thermal conductivity of VIP. The proposed method evaluated the quality of VIP primarily based on the relationship between thermal conductivity and frequency characteristic of the output signal. In addition, we presented a new mean ridge regression extreme leaning machine (M-RRELM) model via improving extreme learning machine (ELM) by ridge regression to modify the relationship between the thermal conductivity and the output signal frequency characteristic. Experiments have shown that the M-RRELM model has higher precision compared with the traditional ELM. The proposed method achieved good performance and was faster than the well known methods.

针对目前真空绝热板导热系数测量时间较长、成本昂贵等问题,提出一种埋入热流计快速测量真空绝热板(VIP)导热系数的方法.首先应用ANSYS仿真证明了测量原理的可行性,建立了VIP导热系数测量系统,以获取内部压力不同VIP的输出信号频率变化值.然后,通过埋入真空绝热板内传感器因温度变化引起的输出信号频率变化与导热系数之间的关系,对真空绝热板的质量和寿命作出评价.最后,利用基于岭回归方法改进了极限学习机的模型(RRELM),提高了极限学习机(ELM)的泛化能力.实验结果表明:埋入热流计法可以实现VIP导热系数的快速测量,且与传统极限学习机相比,提出的RRELM模型通过修正导热系数与输出信号频率变化之间的关系,具有更高的测量精度.

In this paper, a D33-mode piezoelectric micro-accelerometer with Pb1.1(Zr0.52Ti0.48)O3(PZT) thin film is designed, fabricated and tested. Both the polarization and deformation directions of the piezoelectric thin film are horizontal in this structure. With the high sensitivity and natural frequency, the D33-mode piezoelectric micro-accelerometer possesses improved practicality. The influence of filling factor (Γ) and interdigital electrode width (b) on the output voltage is analyzed in this work. The micro-electro-mechanical systems technology is then used to fabricate the piezoelectric accelerometer device, which is based on the Sol–Gel PZT piezoelectric thin film. Performance of the piezoelectric accelerometer micro-devices with the different Γ and b is tested on the vibration table. The experimental results show that the sensitivity of D33-mode piezoelectric accelerometer is inversely to the filling factor and interdigital electrode width. The piezoelectric accelerometer with a filling factor of 0.5 and an interdigital electrode width of 5 μm can generate an output voltage of 149.83 mV.

When the control signal u(t) of totem pole PFC with GaN HEMTs is a function of measurable state variables, the state feedback gain matrix can be determined by applying state variable feedback control with Ackerman formula, so that the poles of closed-loop system can be allocated to the desired position. This correction method is especially beneficial to optimal system control according to performance requirements. By introducing the internal model of reference input, a state space function including the first-order and second-order differential of error is constructed; this novel controller makes controlled system track the reference input signal progressively with zero steady-state error. A 4 kW PFC prototype is designed to verify this design method.

Automatic detection of fabric defects is an important process in the textile industry, which is required to locate and classify microdefects from a large fabric image. We propose a learning-based system for automatic detection of microfabric defects. A segmentation algorithm based on fractal and gray features is applied to extract microdefect regions. Gabor fractal network is designed to further improve identification ability of this approach. The proposed network achieves superior performance in terms of detection accuracy with a much smaller model size. The best testing accuracy rates on dark line, hole, broken yarn, and dirt are 96.9%, 98.0%, 92.9%, and 98.8%, respectively. Experimental results demonstrate the effectiveness of the proposed scheme in defect detection for microfabrics. The proposed system has great potential for automatic detection of microfabric defects. (C) 2019 SPIE and IS&T