Key Engineering Materials Vols. 562-565

Abstract: The distance of air gap is much larger than the mean free path of gas molecules for MEMS devices with small vibration. The nonlinear Reynolds equation can be transformed into linear Reynolds Eq. based on this condition and under certain assumptions. Then the mathematical model of damping of the movable armature is established with the linear Renault equation. The damping characteristics of the movable armature are studied based on the damping force mathematical model. The relation of damping coefficient and the dimensions of movable armature, the dimensions of air gap are analyzed. The research in this paper provides references for the design and analysis of the damping coefficient of the MEMS devices with small vibration.

Abstract: A continue-wave cavity ring down experimental system is established surrounding the micro-sphere cavity. In the experiments of measuring micro-spheres cavity quality factor (Q) upon the system, it is found that photoelectric detectors with different response characteristic have different response to the optical signal which is shut off rapidly. The vibration noise caused by changes of external environment, meanwhile, can be transformed following the change of photoelectric detector properties. With the build of photoelectric detector response model, the mean-square deviation of repeated experiments under the same conditions is used for charactering level of the error caused by vibration noise. The influence of vibration noise to photoelectric detector is discussed in detail, and further analyzes the effect for the cavity ring down time extraction. Then the optimal photoelectric detector (Newfocus1434, 15V/W) is selected to optimize the experimental system. The level of error caused by vibration noise has been decreased from 0.191ns to 1.562ps. Finally, the Q value of micro-sphere cavity is calculated according to fitted value of cavity ring down time, and the experimental correctness is verified by the line-width law.

Abstract: A 532nm Diode-Pumped green laser was used to cut glass with the Micro-Crack control. The Micro-Crack was the micron-sized round-like crack caused by laser in the glass and the line-crack around the round-like crack. This paper researched the generation of the Micro-Crack and discussed how to control it, then researched the stress field in the glass during the cutting by finite element analysis. Propose a new method about the glass cutting which had advantages of low power, low heat effect, irregular-curve cutting and slant cutting.

Abstract: Radio Frequency Identification (RFID) tag is one of the Automatic Identification technology, its application has been involved in all aspects of daily life. A new micro manufacturing technology called Aerosol Jet® printing is described to fabricate the RFID tag in this paper. The fabrication method of Aerosol Jet printing RFID tag is that print the line using sliver ink as the seed first, and then electroplate copper to increase the line width and thickness to reduce the resistance, thus it would get the higher quality factor Q. The width of seed lines printed is 60 μm with the tip of 250 μm in diameter. The inductance value of RFID tag printed is in the range of 2.87 μH to 2.97 μH, it meets the required value of 2 μH to 6 μH.

Abstract: In this paper, mineral phase, elemental composition and size distribution were analysed by means of XRD, XRF and laser particle size analyzer respectively. According to the results of XRD, quartz, illite, calcite and albite were all found in three samples; Dolomite was found only in dustfall; Clinochlore was existed in both PM2.5 and soil. From the results of XRF, elemental compositon of three samples were focused on elemental Na, Si, Al, S, Ca, Fe, Mg, K. Based on the grain size analysis, the size distribution of dustfall mainly ranges from 1µm to 40µm.

Abstract: PM_2.5 samples were collected by Desktop Aerosol Monitor Models 8530 and recorded the meteorological conditions in study site of Yinchuan City simultaneously. The daily averages of PM_2.5 mass concentration varied from 0.134 to 0.222mg m³. The result shows that there are two apparent peaks of PM2.5 concentration in one day. Normally,PM2.5 mass concentration and temperature have some negative correlation. Their morphologies were determined by scanning electron microscopy (SEM). The particles were classified into four groups based on morphology. They were fly ash, mineral matter, irregular shaped mineral particle aggregation and other types. Fly ash and mineral matter were the two dominant types and fly ash is identified as originating from coal combustion or metallurgical plants, mineral matter from natural sources such as soil dust, resuspension of dust from roads.

Abstract: PM_2.5 (sandstorm-related) was sampled at four sites near dust source areas in Northern China in spring 2012. Every site was away from obvious pollution source. After drying 24 hours in a dry dish, X-ray diffraction (XRD), x-ray fluorescence (XRF) and scanning electron microscope (SEM) of all the samples were examined. The main phases were quartz, albite, calcite and mica. SEM observations showed that the particles were mainly irregular shaped, but different sample the particle morphology is slightly different. And the surface was rough because of erosion mark or pores on them. The chemical composition of PM_2.5 is characteristic of high SiO₂ and CaO, while low K₂O, Na₂O. Main elements of the samples were Si, Al, Fe, Ca, which were familiar with crust elements and dust fall components [, but some samples also contained low-level heavy metals like As and Pb.

Abstract: In this article, three parts of work have been done. First, silver nano-particle dispersion had been obtained by liquid chemical reduction method with Ag+ concentration as 2.7mol/l and UV-vis, SEM were used to characterize the silver nano-particles. Then, the dispersion was purified by solvent deposit method for three times with acetone acting as the deposit agent and water-based gravure ink was obtained after adding water, resin, and other additives. The silver content and viscosity of the ink were measured by TG and rheometer. Finally, the ink was used to fabricate transparent conductive film (TCF) with PET as the substrate. The transmissivity, adhesion, conductivity, and the edge sharpness were measured. The results show that ration of silver nanoplates in the dispersion synthesized can reach to 70%. From TG curve, the silver content of the ink is wt. 49%. Viscosity of the gravure ink is 129mPa•s. The transmissivity of the film is around 80% and the calculated resistivity is 1.53×10-4Ω.cm.

Abstract: In this paper, a novel control algorithm for near-infrared spectra detection system based on grating light modulators is proposed. Firstly, the principle of this novel control algorithm is analyzed theoretically, and the encoding and decoding process of two scanning modes based on the control algorithm are obtained. Secondly, the numerical simulation is carried out to evaluate the effect of this control algorithm on the signal-to-noise ratio (SNR) of the spectra detection system. The difference between the SNR of the system under different scanning modes is acquired. When the number of pixels M in a unit becomes larger, the stage number of driven voltages is smaller. In the end, related experiments have been set up, and the feasibility of the control algorithm is validated. By using the novel control algorithm, the detected spectrum of 1340nm narrow band filter could be reconstructed well and the deviations of the peak wavelengths under both scanning modes based on this algorithm are less than 1nm. Furthermore, the novel Hadamard transforms scanning mode based on this control algorithm could not only decrease the complexity of the control circuit but also increase the SNR of the spectra detection system.

Abstract: Noise has become a significant bottleneck limiting the performance of the op amp, and chopper stabilization technology [1] is commonly used to reduce the noise of the op amp. The chopper stabilization technology can significantly reduce the low-frequency 1/f noise of op amp, then reducing the total low-frequency noise of op amp. In this paper, we designed a chopper-stabilized low-noise op amp, and used Cadence software for simulation and debugging.