Key Engineering Materials Vols. 562-565

Abstract: A new kind of wind sensor made up of MEMS resonators is designed in the paper capable of sensing the lift, the resistance and the turbulence of airplane wings by mounting on the surface. The designed wind sensor is made up of four MEMS wind pressure gauges fixed around a square wind resistance block which used to block the wind to change the wind pressure on the surface, and the change of wind pressure is detected by MEMS wind pressure gauges to reveal the air condition on the surface of the airplane wings. As known, a MEMS resonator is a second-order resonant system whose damping factor is mainly dependent on the air pressure, and the characteristic is often used to detecting the airtightness of a sealed chamber for the damping factor is sensitive under high vacuum, while a MEMS resonator with the damping factor sensitive at atmospheric pressure is designed in this paper for sensing wind pressure change, and the MEMS resonator is manufactured on SOI substrates with deep reactive ion etching technology. Also relations between the wind pressure change and the wind speed around a block at atmosphere is revealed by finite element simulation. Compared to traditional wind sensors such as anemometers and Venturi tubes, the designed MEMS wind sensor with a very small size is suitable to mount on different zones of a wing with a large amount to monitor the air condition and have less influence on air flow.

Abstract: A new fabrication methods of thin-film gold electrode is reported. Electrochemical characteristics of self-assembly aptasensor based on MEMS thin-film gold electrode has been studied by lots of experiments, characteristics include immobilizing time, AC impedance, CV curves. Experiments indicate immobilizing time of DNA-SH on gold electrode is more than 15 hours. CV curves and AC impedance of MEMS thin-film gold electrode show the same conclusion that 20μm/L DNA is optimum concentration when DNA is immobilized on gold electrode. Those results present a potential universal method for other aptasensors.

Abstract: We used an electrospinning method to produce ZnO nanofibers for propanol sensing. ZnO nanofibers were electrospun from a solution containing poly(4-vinyl phenol) (PVP) and zinc acetate. The morphology and structure of the as-prepared ZnO nanofibers have been characterized by scanning electron microscopy and X-ray diffraction, respectively. The calcination process of the ZnO/PVP composite nanofibers brought forth polycrystalline würtzite ZnO nanofibers with diameters of 50-70 nm. Under the optimized experimental conditions, the prepared product shows the desirable sensing characteristics towards propanol at 400°C. The high sensitivity, reversible response and good selectivity indicated its potential application as a chemical sensor.

Abstract: This paper presents a modeling method of vibratory microgyroscope with manufacture errors based on parameters identification theroy. owing to the manufacture errors, such as quadrature error and cross-axis perturbation, the resonant vibrations of the drive mode to the sense mode are coupled not only through the Coriolis force. In reality, also by elastic forces, damping and so on. Accurate modeling and identification of manufacture errors enhance significantly the ability to compensate for the consequent errors via feedback/feedforward control strategies. In this article, a really direct model with manufacture errors of the microgyroscope is proposed and the parameters of the model are identified with Frequency-Response Analysis (FRA) and State-Space-based system-identification approach.

Abstract: Novel results relating to the characterization of microlens array production by simulation and micro injection molding were examined to produce precise micro-optics from Polymethylmethacrylate (PMMA), Polycarbonate (PC) as well as Polystyrene (PS). The microlens arrays show 100 lenses in a 10×10 array with a lens radius of 271 µm and a lens depth of 45 µm. The pitches between the lenses are fixed at 800 µm. The surface of the ultra-precision diamond end-ball milled microlens array mold was polished to reduce the surface roughness of the injection molded specimen. The injection molding parameters were optimized to get precise lens geometries with high shrinkage uniformity by simulation and experimental methods. The injection molding results show precise injection molded microlens arrays and PC microlens array shows the best geometrical results compared to the microstructured insert.

Abstract: According to the experimental results of the long-base silicon magnetic sensitive diode, this paper adopted ATLAS software to establish the two dimensional simulation model in order to research the negative resistance characteristics of the long-base silicon magnetic sensitive diode. Deep impurities were introduced into the long base to study the effect of the concentration and the distribution of deep impurities on the current-voltage characteristics of the long-base silicon magnetic sensitive diode. The simulation results showed that the deep impurity in the long base was the main factor that impacted on the negative resistance characteristics of the long-base silicon magnetic sensitive diode.

Abstract: In the paper, a touch mode capacitive pressure sensor with double-notches structure is presented. The sensor employs a special SiC-AlN-SiC sandwich structure to achieve high-accuracy pressure measurement in hash environment such as high-temperature. The analysis to the relation of capacitance and external pressure of the sensor shows that the sensor has high sensitivity and long linear range simultaneously. In addition, the technical process of the sensor has been designed in detail in the paper. The research shows that the sensor packaged in a high-temperature ceramic AlN can withstand higher temperature. Consequently, the sensor can be applied in high-temperature and harsh environment.

Abstract: A kind of fully differential integrator is designed for the modulator of Sigma-delta ADC in this paper. Fully differential structure is adopted to enlarge the amplitude of output, restrain nonlinearity and increase competence of anti-interference. The frequency of signal in this design is 10kHz and the frequency of clock signal is 100kHz. The design of fully differential integrator, capacitive common mode feedback, two-phase unoverlapping clock and switched capacitor integrator are accomplished in this paper. The simulation results in Cadence using 0.5um process show that the low-frequency gain of operational amplifier is 69.87dB, unity gain bandwidth is 37.74MHz, phase margin is 67.73 degrees and slew rate is more than 31V/μs.

Abstract: Piezoresistive sensor was one of the earliest silicon MEMS devices, which based on the theory of piezoresistive. In order to build the piezoresistive IP library for the MEMS foundry, we improved the structures of the piezoresistive based on the achievement of Liwei Lin¹, and new analytic model and design software for square shape membrance has been developed. The ability to calculate sensitivity and linearity of MEMS piezoresistive sensor using the new model have been demonstrated. As results, output voltage, sensitivity and linearity characteristics of MEMS sensor are presented in this paper.

Abstract: The characteristics of MEMS based electrochemical seismic sensors (EC seismic sensors) are presented in this paper. A numerical model is set up, and a series of vibration test is established. The numerical simulation and vibration test results are illustrated and the difference between them is discussed.