bluuebunny/crossref_metadata_2025 huggingface dataset:
A Robust Location Algorithm for PCB's Solder Joints
Authors: Wu Fu Pei , Geng Yun Yi , Li Sheng Ping
Published: July 2013

Printed circuit boards (PCBs) are being widely used in the electronic packages. Solder joints are often used to interconnect chip resistors and other components onto PCBs. The defects of solder joints will increase quality costs and deteriorate performance. If solder joints cant be located accuracy, AOI system will not inspect solder joints at the right place of solder joints and must lead to misjudgement. Especially, the misjudgement will increase dramatically under uncertain noise disturbance to micro-size solder joints due to inaccuracy location. In this work, an eliminating uncertain noise method is proposed and a robust location algorithm for PCBs solder joints is present. Firstly, some location windows are set based on technology parameters of chip and its solder joints, and solder joints feature image is obtained from it solder joint image based on series of image pre-processing. Secondly, the layout frame outside solder joints, which is viewed as a noise disturbance to location, is extracted as a binary image and is projected to X axis and Y axis, then the smaller region, which include solder joints but no the layout frame, is obtained based on calculating the sum features function of layout frame. Thirdly, the blob feature image of solder joints is extracted from its gray images of red, green, blue layers; it may have some noise blob around solder joints feature, then an evaluation function is develop to judge blob, which maybe belongs to noise or solder joints feature, and only solder joints feature are remained. Fourthly, with the help of setting solder joints windows, the integrated projection method is developed to locate solder joints. Finally, the proposed location method is compared with other two algorithms in the experiment. Experiments result illustrates that the smaller the solder joint size, the better location accuracy and efficiency is obtained than other two mothers.
An Investigation into the Influencing Factors for Polymer Melt at the Filling Stage in Micro Injection Molding
Authors: Zhuang Jian , Wu Da Ming , Zhang Ya Jun , Wang Lin , Wang Xiong Wei , He Ying , Hu Wei
Published: July 2013

The flow behaviors for polymer melt at the filling stage in micro injection molding are different from those in conventional injection molding due to the miniaturization of plastic parts. This paper focuses on the study of the effects of three main influencing factors, including the microscale viscosity and wall slip, on melt filling flow in microscale neglected those in conventional injection molding process. The theoretical models and the interrelation of these factors in microscale channels were constructed by means of the model correction method. Then, the micro melt flow behaviors were investigated with comparisons of the available experimental data. The results indicate that the dimensions affect the shear rates and viscous dissipation, which in turn affects the apparent viscosity. Finally, the conclusion is that the melt flow behaviors in microchannels are different from those in macrochannels owing to these significant influencing factors.
Study on the Air Damping of the Movable Armature
Authors: Liu Ben Dong , Yang Jia Hui , Wu Yu De
Published: July 2013

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.
The Effect of Vibration Noise for Cavity Ring Down Time Extraction
Authors: Meng Xiang Ran , Zhao Yu , Wang Xiao Qian , Xu Peng Fei , Zhang Wen Dong , Yan Shu Bin
Published: July 2013

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.
Fabrication of Transparent Conductive Film Using Water-Based Nano-Silver Gravure Ink
Authors: Li Wei Wei , Mo Li Xin , Fu Ji Lan , Li Wen Bo , Ran Jun , Fan Xin Ming , Li Ya Ling , Li Lu Hai
Published: July 2013

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.
Effect of the Surface Roughness on the Detecting Capacitance
Authors: Zhang Hai Feng , Liu Xiao Wei , Li Hai , Chen Nan , Fu Yi Bo
Published: July 2013

With the MEMS technology advancement, electronic devices are miniaturized at every development node. The surface roughness is affecting the detecting capacitance of MEMS device because surface to volume ratio is increasing rapidly. A novel model with one rough electrode is investigated in this paper. The impacts of surface roughness on detecting capacitance are analyzed. The image of height percentage is used to describe the surface roughness of electrode sample. The function of the surface roughness is obtained according the method of curve fitting. The effect of surface roughness on the capacitance is calculated. The results demonstrate the capacitance increases with the surface roughness.
Mathematical Modeling of a Direct Methanol Fuel Cell with a Novel Structured MEA
Authors: Suo Chun Guang , Zhang Wen Bin , Quan Xiao Hong
Published: July 2013

Two one-dimensional, steady-state numerical models are presented to evaluate the performance of direct methanol fuel cells (DMFCs) in different aspects. One model is applied to simulate the double-layered catalyst structure, which reveals to greatly reduce both cathode and anode overpotential. Another model is created to simulate the effect of methanol and oxygen concentration on power density response in DMFC. In the numerical results, it was found that a DMFC consisting of double-catalyst layer electrodes exhibited many advantages over the traditional MEA, and the performances of the single cell are enhanced.
Modeling Analytically the Pull-In of Double-Cantilever Structure
Authors: Yu Hui Jin , Yang Hui , Shen Hua Qing , Peng Bei , Zhou Wu
Published: July 2013

This paper presents an analytical model based on the basis finite element analysis to solve the nonlinear behavior of double-cantilever structure. The structure beam is replaced with a series of beam elements by traditional finite element method. The deformation curve of the beam is calculated by gradually loading voltage in small increments, and pull-in behavior is identified when the convergence of the deflection iteration cannot be achieved after voltage increment. This method considers the effect of deformation on stiffness by establishing a new equivalent stiffness matrix for each voltage step on the basis of the results of previous steps. Through this approach, we prevent the approximate errors of the stiffness matrix from accumulating. The analytical results show good agreement with those obtained by using multiphysics coupling software.
Modeling of Ultra-Precision Piezodriven Positioning System
Authors: Chen Hui , Tan Yong Hong , Zhou Xing Peng , Zhang Ya Hong , Dong Rui Li
Published: July 2013

A neural network based approach for the identification of the rate-dependent hysteresis in the piezoelectric actuators is proposed in this article. In this method, a dynamic hysteresis operator for expanded input space is proposed to extract the change-tendency and rate-dependency of the dynamic hysteresis, the parameters of the hysteretic operator is identified using genetic algorithm. An expanded input space involving the original input variable and the new operator is constructed. Thus, based on the expanded input space, the neural networks can be utilized to approximate the behavior of the rate-dependent hysteresis. Furthermore, the dynamic performance of the model is improved because of the existence of dynamic operator. Finally, the method is used to the modeling of hysteresis in a piezoelectric actuator. The experimental results are presented to verify the effectiveness of the proposed approach.
Optimization Analysis on the Transmission Characteristics of Semi-Circle Long-Range Dielectric-Loaded Surface Plasmon-Polariton Waveguides
Authors: Cheng Li Bin , Cheng Xing Liang , Dou Zhen Ling , Zhang Guan Mao
Published: July 2013

Semi-circle long-range dielectric-loaded surface plasmon-polariton waveguide (LR-DLSPPW) is proposed, in which a thin and narrow metal stripe (15-nm-thick and 500-nm-wide) is sandwiched between a semi-circle dielectric ridge(with the refractive index of 1.535 ,the radius of 777 nm) and a dielectric film (with the refractive index of 1.493) supported by low-index substrate (with the refractive index of 1.34). The mode effective index, propagation length, mode width and figures of merit of the fundamental mode supported using the finite-element method are calculated at the telecom wavelength λ =1.55μm for different dimensions (t) of the dielectric film. It was calculated that the optimized structure have the maximized parameters with figures of merit 3.75×10¬6and propagation length 3.7mm at t=570 nm. The semi-circle LR-DLSPPW structure is found to exhibit about 20% increase of the propagation length as compared to the conventional rectangular LR-DLSPPW while ridge thickness t≤600 nm. The proposed configuration allows for easy connection to electrodes enabling, and is technologically simple being compatible with planar fabrication using UV-lithography.
Sub-Pixel Image Matching Based on the Fractal Dimension
Authors: Luo Yuan , Jiang Qiu Zhao , Zhang Yi
Published: July 2013

The technology of image matching is very important in the field of image analysis. Studying on image correlation is the key to improve the accuracy of image matching, while the fractal self-similarity has the unique potential in making full use of image correlation. This paper put forwards a matching algorithm of the sub-pixel image matching based on fractal dimension. Firstly, by searching template subarea based on traverse in being matched image, and the sub-subareas are classified. Then, the fractal dimension of subareas and sub-subareas is calculated by using the optimal box counting method. The similarity maximum position can be found according to the statistical correlation. Finally, fractal interpolation method is used to improve the precision of image matching. Both theoretical analysis and experimental results show that this approach has good matching effect.
Design of an Array Bionic Vector Vibration Sensor Based on MEMS
Authors: Liu Lin Xian , Zhang Guo Jun , Zhang Wen Dong
Published: July 2013

In the process of a physical procedure, more than one vibration signals should be measured, whose value and frequency are in a wide range. Therefore, in such a situation, a single sensor can hardly meet the testing requirement. To solve this kind of problems, a kind of aligned array MEMS bionic vector vibration sensor is proposed. This aligned array vibration sensor consists of four micro-structure sensors and the testing ranges are 10g, 100g, 500g, and 1000g. On the basis of the mathematical model, the array sensing unit was simulated by ANSYS. The test was presented at last. The experiment results show that both the two direction of the aligned array vibration sensor have high sensitivity, good linearity and good output stability. The sensitivity of the X direction is 2.6134mv/g and Y is 2.5563mv/g, the linearity of X direction is 0.99991and Y is 0.99968.
Fabrication and Characterization of Tin Oxide Inverse Opal by Template Method
Authors: Wang Jin Quan , Wu Xin Hua , Wu Yuan Yuan , Yuan Sai Sai , Xu Yan Mei , Chen Xiao Bing , Zhang Ming
Published: July 2013

In this study, Tin Oxide (SnO2) inverse opal was fabricated by infiltrating SnO2 sol-gel precursor solution into Poly Styrene (PS) spheres crystal template which was generated via evaporative deposition self-assembling, then was heat treating at 500°C for two hours in controlled atmosphere box furnaces. PS spheres crystal template was characterized by Scanning electron microscope and Ultraviolet-visible-near infrared absorption spectrometer. The SnO2 inverse opal was characterized by Scanning electron microscope, Energy Diffraction Spectrum, X Ray Diffraction. The large-area, highly ordered SnO2 inverse opal was achieved in this paper.
The Key Technologies of SOI Micro-Accelerometer Front Release Process
Authors: Zhang Zhao Yun , Shi Zhi Gui , He Xiao Ping , Du Lian Ming , Zhang Hui , Peng Bo
Published: July 2013

In order to develop the SOI micro-accelerometer front release process, this paper discusses in details the key technologies of the process. There are three problems need to be resolved: the corrosion of the electrode, the corrosion rate of the buried silicon dioxide layer as well as the anti-adhesion of the micro-structure. The corrosion characteristic of the electrode is studied, and a metal electrode of high ability of anti-HF acid corrosion is designed, after release of the micro-structure, the electrode does not fall off. The corrosion property of the buried silicon dioxide is studied, and the corrosion rate is exactly known for 2um and 5um thick buried silicon dioxide layer. Based on this, the buried silicon dioxide layer etching time can be controlled, preventing over-etching of the oxide layer. The adhesion of comb fingers and the mass with the substrate is settled at last. By electron microscopy tests, found that the process can get a good micro-structure surface, with smaller footing effects. By test, the sensitivity of the accelerometer is about 144.5mv/g.
Research on the Method of Laser Trimming to Reduce the Mode Coupling Error of Micro-Machined Vibratory Gyroscopes
Authors: Cui Hong Juan , He Kun , Xiao Ding Bang , Hou Zhan Qang , Liu Xue , Wu Xue Zhong , Su Jian Bin
Published: July 2013

Large mode coupling error would seriously restrict the improvement of gyroscope performance. In order to decrease the adverse influence from mode coupling error, this paper studied the formation mechanism of mode coupling error for a micro-machined vibratory gyroscope and certified the result studied by ANSYS analysis. Based on our analysis, it is found that removing material from both sides of the center lines of oscillation could arouse errors of anti-phase each other, which demonstrates that trimming could reduce mode coupling error on the other hand. Finally, experimental study was implemented on the micro-machined vibratory gyroscope by UV laser micromachining technology. Results indicated that laser trimming method on the basis of the phase relationship between mode coupling error signal and driving signal could effectively degrade the error. For certain prototype, the peak-peak voltage of the mode coupling error could be reduced from 6.6V to 0.2V after trimming when there is no angular velocity input.
Micro-Displacement Sensing Circuit for Gyroscope with Levitated Rotor
Authors: Ren Ming Yuan , Liu Xiao Wei , Zuo Wen , Mao Zhi Gang
Published: July 2013

This paper presents a micro-displacement sensing circuit, which can detect sensing capacitors of levitated rotor. To ensure the high resolution, noise analysis of pre-amplifier of micro-displacement sensing circuit is conducted. The results show that choosing low noise amp and decreasing Cf /C1 can reduce the electronic noise.
Analysis of Fabrication Errors on Micro-Spring's Elastic Coefficient
Authors: Shu Xin , Lou Wen Zhong , Zhao Yue , Guo Ming Ru , Fu Yue , Wang Ying
Published: July 2013

Because fabrication errors have a great influence on micro-springs elastic coefficient, and it is difficult to reduce the influence through fabrication process methods at this stage, the authors propose solutions through design process to reduce the sensitivity of Elastic coefficient of fabrication errors. The authors derived error propagation formula through multivariate function Taylor series expansion method, and made a quantitative analysis of the influence of fabrication errors, then summarized the influence rules of the size parameters on dispersibility of elastic coefficient K, finally proposed the method to degrade device performance dependent on the fabrication precision.
Design of Monolithic Differential Quartz Vibrating Beam Accelerometer with Optimized Electrode Layout
Authors: Wang Wen Pu , Zhou Zhen , Feng Li Shuang , Yao Bao Yin , Yang Gong Liu
Published: July 2013

The electrode layout determines the piezoelectric performance of quartz resonator and directly affects the precision of the quartz VBA. We presented a novel monolithic differential quartz VBA with optimized electrode layout and solved the lock-in problem due to mechanical coupling. Based on the mass-equivalent system, an analytical model was developed and the uncoupling condition of the monolithic differential quartz VBA was deduced. Then we proposed five different electrode layouts and the optimum one was determined via simulation of piezoelectric and harmonic characteristics of quartz resonator with ANSYS. As a result, the mechanical coupling can be eliminated and at the same time, ±100 g measurement range and 80Hz/g scale factor can be achieved. The optimum electrode layout can drive quartz resonator in the desired modal. The presented device with advantages of miniaturization, low mechanical coupling, none assembly errors and high electromechanical coupling efficiency is very promising in the high-precision quartz VBA.
Design of Conductive MWNTs/SiO2 Humidity Sensor Interface ASIC Based on AC Signals
Authors: Li Tuo , Liu Xiao Wei , Yin Liang , Dong Chang Chun
Published: July 2013

Previous research on MWNTs/SiO2 humidity sensing film by our work group has proved that MWNTs sensor has a different response mechanism to humidity at AC testing signals and shows greater testing stability and higher sensitivity, compared with traditional DC signal measurement. An interface circuit for conductive MWNTs/SiO2 humidity sensor is designed in this paper for humidity detection and prospection in miniaturization and integration. It aims at detecting the sensor’s humidity sensitive conductance signal at AC testing signals, and inhibiting the interference of capacitance signals. The ASIC demodulates the two signals by their phase difference and outputs a direct voltage proportional to conductance. The layout for ASIC is drawn by standard 0.5um P2M2 CMOS process and has a total area of 4*2mm2. In circuit level simulation by HSPICE which introduces practical data of the sensor’s humidity sensing characteristics, the relation of circuit output to conductance turns out to have great linearity at no more than 300 kHz and zero offset can be neglected at less than 100 kHz frequency. It is feasible to select proper testing frequency for high sensitivity and stability and make further investigations on the sensor’s frequency property.
The Design of a Micro Self-Powered Wireless Analog Sun Sensor
Authors: Zhang Gao Fei , Wang Hui , You Zheng
Published: July 2013

This paper presents a new type of micro self-powered wireless analog sun sensor. The mask with aperture of the sun sensor, developed by glass coated process, reduces the impact on accuracy caused by second reflection of the light, and also promotes system’s external thermal radiation ability. With aluminum substrate process, the processing circuit is integrated on the bottom cover of the sun sensor, which saves the conventional processing circuit needed space and reduces the complexity of system’s structure. Self-powered and wireless data transmission improve the system’s application flexibility. The simulation results and preliminary experiments show that the accuracy of the system has the ability to reach 0.2° in the whole 120°×120° FOV and the solar cells’ minimum output power is 90mW which is able to meet the power consumption requirements of the system circuits.
Sine-Wave Exciting Circuit for Quartz Vibrating Gyroscope
Authors: Wang Qing Yi , Liu Xiao Wei , Zhang Rui , Yin Liang , Zhou Zhi Ping
Published: July 2013

Quartz vibrating gyroscope is a kind of angular rate sensor which is the compromise between the high performance and the small volume. Improvement of the performance is a focus of reach. In this paper, a sine-wave exciting method is discussed. A sine-wave exciting circuit is design and processed with 0.5μm CMOS processing technology. During comparing the sine-wave exciting response and the square-wave one, the sine-wave exciting circuit is more beneficial to improve the performance of the quartz vibrating gyroscope.
Replication, Characterization and Simulation of Micro Injection Molded Microlens Arrays Using Technical Amorphous Polymers
Authors: Chen Lei , Kirchberg Stefan , Jiang Bing Yan , Xie Lei , Qiu Qing Jun , Ziegmann Gerhard
Published: July 2013

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.
Micro-Hole Drilled by EDM-ECM Combined Processing
Authors: He Xiao Long , Wang Yu Kui , Wang Zhen Long , Zeng Zhao Qi
Published: July 2013

A new method for drilling micro-hole called EDM-ECM combined processing is proposed in this paper. This method consists of EDM shaping and ECM finishing, and they are carried out in sequence on the same machine tool with the same electrode but different dielectric medium. Micro-hole drilling experiment was done by micro-EDM, micro-ECM and EDM-ECM combined processing. The results show that the machining efficiency is improved by 9.2 times compared to conventional micro-ECM, and machining precision and shape accuracy of micro-hole are much better. The surface quality and mechanical property of the workpiece are improved, since the recast layer and surface defects generated by EDM are removed completely by ECM finishing. It proves that this combined machining method is possible and useful in the field of micro-hole drilling.
Photothermal Microactuators Fabricated by LIGA Technology
Authors: Wang Bo , Shi Bin , Yi Fu Ting , Zhang Dong Xian , Zhang Hai Jun , Zhang Tian Chong , Liu Jing , Ma Li Na
Published: July 2013

A novel microactuator based on photothermal expansion is introduced, which is actuated by laser beam eliminating external circuit. The mechanism of the photothermal expansion is theoretically analyzed, and the working principle of a U-shaped photothermal microactuator with two arms is introduced and the lateral deflection is calculated. LIGA technology involving X-ray lithography and electroplating is introduced to fabricate photothermal microactuators. The fabrication process with LIGA technology is introduced and important details such as X-ray mask and electroplating are discussed. Photothermal microactuators with different structures are fabricated by LIGA technology at Beijing Synchrotron Radiation Facility (BSRF) and tests are carried out with laser beam. The deflection of a V-shaped photothermal microactuator of Ni material can reach 25.8 μm under the control of a 1064 nm, 800 mW laser and a U-shaped can reach about 11 μm at an 808 nm, 600 mW laser.
Preparation of Graphene-Containing Composite Film and the Research on its Thermal Conductivity
Authors: Li Feng Xian , Jin Shuang Ling , Zhou Xiao Long , Zhang Rui , Jin Ming Lin
Published: July 2013

A smooth and flexible carbon film was prepared via liquid exfoliation method followed by liquid evaporation using the natural flake graphite as the starting material. The XRD and Raman results demonstrated that the obtained film is composed of chemically reduced graphene, graphene oxide and graphite. The thermal transport property of the as-obtained film was investigated by light flash measurements. It is found that the as-obtained graphene-containing composite film has a high in-plane thermal diffusivity (2157 m2/s), and the corresponding thermal conductivity (754 W/m K) is higher than the other metal and normal graphite materials, which is very promising for applications requiring 2D heat conduction.
Application of Nanomaterials in the Fields of Drilling Fluids and Completion Fluids
Authors: Ma Cha , Li Long , Li Shuang , Han Xiu Ling
Published: July 2013

Nanotechnology generates nanomaterials with many unique characteristics, which could play an active role in intensifying mud cake quality, raising cuttings removal ability, reducing friction, maintaining borehole stability, and improving the cementing quality. In this paper, a series of nanomaterials were introduced, and all of them had great influence on the properties of drilling fluids or completion fluids, which would be significantly important to wellbore stability, formation damage control, borehole cleaning, safety drilling, cementing quality, environmental protection, and the improvement of the progress and success rate of petroleum development and production. Finally, the further applications of nanomaterials in drilling fluids and completion fluids are also prospected.
Microfluidics Design for Single Cell Detection
Authors: Du Shao Bo , Sang Sheng Bo , Zhang Wen Dong , Hu Jie , Li Peng Wei , Li Gang , Feng Hui
Published: July 2013

Here we demonstrate a microfluidic-based analysis system based on single cell capture array, which can physically trap individual cell using micrometer-sized structures. A stable and in vivo-like microenvironment was built with the novel structure at the single-cell detection level. The microfluidic-based design can decouple single cells from fluid flow with the help of micropillars. The size and geometry of the cell jails are designed in order to discriminate between mother and daughter cells. It provides an experimental platform to efficiently monitor individual cell state for a long period of time. Furthermore, the parallel microfluidic array can ensure accuracy. In addition, finite element method (FEM) was employed to predict fluid transport properties for the most optimal fluid microenvironment.
The Thermochemotherapy Effect of Mn0.5Zn0.5Fe2O4 Magnetic Fluid Hyperthermia Combined with As2O3 on GLC-82 Cells
Authors: Zhang Hao , Hou Xin Xin , Lin Mei , Ni Hai Yan , Yuan Chen Yan , Li Hong Bo , Zhang Jia , Wang Li , Li Yun Tao , An Yan Li , Zhang Dong Sheng
Published: July 2013

AIM: To study the preparation and characterization of the Mn0.5Zn0.5Fe2O4 (MZF) magnetic nanoparticles and the antitumor function of MZF nanomagnetic fluid hyperthermia (NMFH) combined with As2O3 on GLC-82 cells.METHODS: The MZF magnetic nanoparticles were prepared by the method of chemical coprecipitation.,which were detected by transmission electron microscopy (TEM) and energy dispersive spectrometry (EDS). In vitro heating test of MZF magnetic fluid in an alternating magnetic field (AMF) was carried out. After that, we studied the therapeutic effects on cultured GLC-82 cells treated by thermochemotherapy of NMFH combined with As2O3 at various concentrations (2,5,8μM) were evaluated by MTT assay and flow cytometry assay (FCM).RESULTS: The MZF magnetic nanoparticles were prepared successfully. Their shapes are approximately global and their diameters are about 30 nm. EDS showed MZF magnetic nanoparticle contained Mn, Zn, Fe elements. The corresponding fluid of MZF magnetic nanoparticle could rise to 40~50°C due to different concentration in a AMF and keep stable from then on. MTT assay and FCM revealed that the thermochemotherapy effect of the MZF magnetic nanoparticles combined with As2O3 can cause significantly inhibit cellular growth observed by MTT test assay and obviously induce cellular apoptosis by FCM detecting (p<0.05). The apoptotic indexes of GLC-82 cells of the pure As2O3 group,pure MZF magnetic nanoparticles hyperthermia group and thermochemotherapy of NMFH combined with As2O3 group were 4.98%,16.30%,22.53%,respectively,while the apoptotic index of the negative control group was 0.56%.CONCLUSION: The MZF magnetic nanoparticles successfully were prepared through improved co-precipitation process and have good power absorption capabilities in the high frequency AMF, then they can rise to a steady temperature. MZF magnetic nanoparticles have hyperthermia effects on tumor and their antitumor effect significantly increase when combined with As2O3.
A New Fabrication Method for Paper-Based Microfluidic Device Used in Bio-Assay
Authors: Li Zong An , Hou Li Ya , Zhang Wei Yi , Zhu Li
Published: July 2013

Paper-based microfluidic devices have a significant potential for low-cost diagnostics in the developing world. This study reported a simple fabrication method based on the digitallization of microfluidic technology for paper based microfluidic devices. Melted wax was jetted steadily with PZT actuated microfluidic pulse inertia driving system and pulled-forged glass micronozzle in the form of droplets. The wax melted into filter paper to form hydrophobic wall and different patterns for paper microfluidic devices were made. The influence of system parameters such as driving force, frequency, the fabrication process and the tip diameter of glass micronozzle on the wax line width was experimentally studied. 75 μm500 μm wax lines were achieved with the wax printing system. The paper microfluidic devices fabricated could lead the capillary action of black ink and the color change reaction of NaOH and phenolphthalein solution. Result showed that the wax printing system is simple structured and this method suggests a novel path to develop simple, inexpensive, and portable diagnostic assays.
Transient Pull-In Analysis of Micro-Plate with Fluid-Structure Interactions
Authors: Lin Xie Zhao , Ying Ji , Huang Jian Meng
Published: July 2013

Electrostatic micro-devices are simple but important for MEMS applications. Precise dynamic descriptions of these devices are often hard to obtain due to the electrostatic nonlinearity and the fluid-structure interactions in devices. Here we present a comprehensive electrostatic-mechanical-fluidic coupling transient analysis for the pull-in process of two ends fixed micro-plate device. The numerical results are compared with the published experiment works of other researchers available in the literature, and thus the model had been validated. After that the proper orthogonal decomposition approach is performed for the snapshot matrixes which are sampled from an ensemble of the fully finite element results. The resulted spatial distribution modes of pressure show a higher spatial frequency toward the middle of the micro-plate, which indicates that the pressures at the moving edges of the plate are not equal to ambient pressure. Due to the increasing demands for simulation accuracy, the electrostatic-mechanical interactions and the nonlinear features of viscous loss from the surrounding fluid have to be taken into account in details.
Electrodeposition of Three-Dimensional (3D) Ag/Pd Bimetallic Nanodendrites and Application for Total Nitrogen Determination
Authors: Hu Jing Fang , Sun Ji Zhou , Bian Chao , Tong Jian Hua , Xia Shan Hong
Published: July 2013

A novel micro-sensing chip for detecting total nitrogen (TN) was reported, which was based on 3D bimetallic Ag/Pd nanodendrites for electrocatalystic reduction of nitrate. The 3D structured Ag/Pd nanodendrites were synthesized by electrodepositon of Ag and Pd on gold interdigitated microband array electrode (Au-IDA). Such 3D Ag/Pd bimetallic nanodendrites possess an extremely high electrocatalytic activity for nitrate reduction in alkaline media at pH 12.5 hence realizing an excellent performance of TN determination without pH adjusting. The electrochemical detection limit of TN is 0.1mgL-1 and the measurement results of real water samples showed a relative error of less than 10% with UV spectrophotometric method. The present micro-sensing chip has significant potential for developing of portable and inexpensive TN instrument for on-line environmental measurement.
Preparation and Photocatalytic Properties on ZnO/TiO2 Nanotubes
Authors: Liu Yang Lin , Duan Xue Chen , Li Yao Ming , Liu Yan Yan
Published: July 2013

In order to study on the effect of the content of Zn to phase morphology and photocatalytic performance of ZnO/TiO2 composite material, we prepare ZnO particle finishing with surface chemistry and make tubular TiO2 with hydrothermal. Using characterization methods like XRD,SEM,TEM to explore how various conditions such as different incineration temperature, atomic ratio, etc can interfere with morphology, structure and photocatalytic performance of composite. In this experiment, the surface of TiO2 nanotubes combusted under the temperature of 673K for 2h are smooth;Zn:TiO2=1:4 to achieve uniformly and firmly distributed nano composite particles which grain size is 11nm on the surface of TiO2 nanotubes,including 2-3nm ZnO particles on tubes; 0.1mol/L sodium hydrate-ethanol solution as precipitant to obtain ZnO/tubular TiO2 composite materials which are highly dispersed and deposited on the surface of tube-shaped TiO2; Zn:Ti=1:4 reach the best catalytic result.
Controllable Synthesis of Single-Crystal Monolayer Graphene on Copper Foils by Low-Pressure Chemical Vapor Deposition
Authors: Guo Lei , Chen Xue Kang , Wang Lan Xi , Cao Sheng Zhu , Bai Xiao Hang , Zhang Chao , He Yong Min , Gao Hui
Published: July 2013

~50 μm single crystal graphene with hexagonal flower shape was synthesized on copper foils by low pressure chemical vapor deposition (LPCVD). The strong influence of Cu foils annealing on suppressing the nucleation of graphene was observed. Scanning electron microscopy (SEM), Optical microscopy (OM), and Raman spectrum showed that single crystal graphene as grown was monolayer with high quality. Suppressing nucleation through an annealing procedure offers an promising way to grow large-scale single crystal graphene controllably.
Design and Fabrication of an Aerodynamic Micro-Air Journal Bearing Using Micro-Wire Electrical Discharge Machining
Authors: Wang Yu Kui , Zeng Zhao Qi , Wang Zhen Long , He Xiao Long
Published: July 2013

This paper proposed a removal analysis and a contouring strategy of accurate micro-WEDM processing for an aerodynamic micro-air journal bearing for micro-gas turbine engine. It is designed based on aerodynamic theory and can be self-acting by the compressed air pressure. The rotor is stably rotated in a relatively low speed which is below one hundred thousand revolutions per minute, and is much lower than other references. The extended and trimmed tool path is adopted in this paper, and the cusp at the corner of the micro-air journal bearing is obtained by this method which is better than the common arc tool path. The inner and outer diameter of the micro-air journal bearing with a satisfactory shape and good surface quality is 1.068mm and 1.165mm, respectively. The minimum radius at the bottom of wedged-structure is 15.9μm. The kerf of the blanking is 43μm, and the machining discharge gap is 18μm under this machining conditions. The MRR calculated by experimental data is 0.00144mm2/min.
Characterization of Glass-Ceramics by TEM
Authors: Liu Xiao Qing , Xie Jun Lin , He Feng , Yang Hu
Published: July 2013

The characterization technique of glass-ceramics by TEM was discussed by comparing the effects of single layer carbon film technique and double layers carbon film technique on the microstructure of Li-Al-Si glass-ceramics. The results show that double layers carbon film technique can improve glass-ceramics sample’s conductivity, reduce the induction of elctron beam on glass-ceramics, and avoid the temperature increasing of glass-ceramics particles caused by the charges aggregation on the particles’ surface when TEM electron beam hit down, prevent glass-ceramics from crystallization and the transformation of microstructurec. So, compared with single layer carbon film technique, double layers carbon film technique is more suitable for the research of microsture of glass-ceramics by TEM.
Determination of Ascorbic Acid Based on a Platinum Nanoparticles Modified Au Electrode
Authors: He Jia Hong , Gao Zhi Qiang , Song Zhong Rong
Published: July 2013

A Platinum nanoparticles modified Au electrode has been successfully fabricated by using an in situ growth method. In this method, the Platinum nanoparticles could be grown on the Au electrode surface via the one-step immersion into the mixture of H2PtCl6 (analytical grade, 1g/L), NaBH4 (analytical grade) and polyvinylpyrrolidone K30 (PVP, analytical grade). A certain amount of PVP was added into the reaction system to prevent the coagulation of the Platinum nanoparticles, which obtained by the chemical redox reaction of H2PtCl6 and NaBH4. The structures and morphologies of the Platinum nanoparticles were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) . The direct electrochemical behavior of ascorbic acid in 0.3 mol/L NaCl medium at the Platinum nanoparticles modified electrode has been investigated in detail. Compared to a bare Au electrode, a substantial decrease in the overvoltage of the ascorbic acid was observed at the Platinum nanoparticles modified electrode with oxidation starting at ca. 0.20 V vs. SCE (saturated KCl). At an applied potential of 0.18V, this modified electrode produced high and reproducible sensitivity to ascorbic acid and linear responses were obtained over a concentration range from 0.600 to 3.267 μmol/L with a detection limit of 1.9 nmol/L(S/N=3). The fabrication method of this sensor, which has highly sensitive, low working potential, and fast amperometric sensing to ascorbic acid, is simple and without using complex equipment. In addition, the sensor has been successfully used to detect ascorbic acid in real sample, thus is promising for the future development of ascorbic acid sensors.
Experimental Investigation of the Thermal Conductivity of the Titanium Carbide Thin Films on Silicon Substrate
Authors: Bai Su Yuan , Huang Zheng Xing , Tang Zhe Nan
Published: July 2013

Thermal conductivities of the titanium carbide thin films with thickness ranging from 58 to 158 nm were measured at room temperature using the transient thermoreflectance technique. The results show that thermal conductivities of these films are lower than corresponding bulk material values. The reduction in the thermal conductivity can be attributed to the material microstructure brought by the thin film fabrication process. Both the film thickness and the atom ratio of Ti/C are the important factors. The thermal conductivity increases with the increasing film thickness and atom ratio of Ti/C. It also indicates that the material beneficial to thermal management and thermal design could be fabricated by improvement of the deposition techniques.
Magnetron Sputtering Ni-Cr Alloy Thin Film Resistance Temperature Characteristic Study
Authors: Tang Li , Hu Dong Ping
Published: July 2013

Based on microelement manufacturing, semiconductor lithography technologies, The sensor chips fabricated to be small volume, high reliability, easy mass production, low cost, can resist to bad environment. In thin film pressure sensor chip, Ni-Cr alloy thin film is the key part, mostly influence the main electrical characteristics of the film pressure sensor chips. The resistance temperature characteristics changes on account of different proportions of Ni-Cr alloys. In this paper, two different proportions of Ni-Cr alloys were deposited and heat treated, the TCR of the alloys were tested, the causes were analyzed.
Oxidation-Induced Redshifts in the Energy Gap of Silicon Quantum Dots
Authors: Zeng Jie Qiong , Yu Hong
Published: July 2013

To investigate the effects of Si/O bond at the surface of silicon quantum dots (Si QDs) on the electronic properties of Si QDs, first principle calculations have been performed for Si QDs consisting of 10-87 Si atoms (0.6-1.5 nm in diameter) by using the CASTEP software package. In these calculations the Si dangling bonds on the surface of Si QDs are passivated by hydrogen atoms and oxygen. Four different oxygen configurations have been studied, they are double-bonded, backbonded, bridge-bonded and inserted, respectively. We find that a significant reduction of energy gap is caused by the presence of double-bonded oxygen, whereas for other three oxygen configurations there is just a slight reduction on energy gap. As a result, the model which contains Si=O bond is considered the most appropriate to explain the photoluminescence redshifts in oxidized porous silicon.
Preparation and Photocatalytic Activity of Nd3+and CTAB Co-Doped Nanometer TiO2 Thin Films
Authors: Yao Lan Fang , Tang Xiong , Yan Xin Pei , Li Lin
Published: July 2013

Pure TiO2, Nd3+doped TiO2 and Nd 3+-CTAB co-doped TiO2 nanometer thin films were prepared by the sol-gel technique with tetrabutyl titanate and neodymium nitrate as raw materials and surfactant cetyltrimethylammonium bromide (CTAB) as template. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-Visible absorbance spectroscopy (UV-Vis). The photocatalytic activity was evaluated by photocatalytic degradation of methyl orange. The results show that the all samples calcined at 500°C are all anatase, and there are slight red shifts of the Nd3+doped TiO2 and Nd3+-CTAB co-doped TiO2 films compared with pure TiO2 films and the red shift of Nd 3+-CTAB co-doped TiO2 is more obvious than that of Nd 3+ doped TiO2, which is beneficial to improve the photocatalytic efficiency. The1.0% Nd3+-CTAB co-doped TiO2 nanometer film calcined at 500°C had excellent photocatalytic efficiencies and the degradation rate of the film is more than 90% after 120 min.
Study on the Preparation of Streptomycin Imprinted Polymers on the Surface of Silica Micro and Nano Spheres
Authors: Li Zhi Fei , Li Jun Jie , Huo Dan Qun , Yang Mei , Li Xian Liang , Wang Guo Min , Fa Huan Bao , Hou Chang Jun
Published: July 2013

The integration of molecular imprinting technique and solid-phase extraction (SPE) implements an effective alternative for sample pre-concentration in the determination and analysis of veterinary drug/pesticide residues. Herein, we reports a preliminary study on the preparation of streptomycin imprinted polymers on the surface of silica micro-spheres (with an average size of 50μm) and nano-spheres (with an average size of 500nm) via sol gel method. A mixed solution of tetrahydrofuran, ethanol and water (volume ratio is 7:1:1) was choose as dispersion agent, 3-aminopropyltriethoxysilane and phenyltriethoxysilane as functional monomers, and tetraethyl orthosilicate as cross-linker, while ammonia solution served as catalyst in the polymerization process. Scanning electron microscopic characterization was employed, suggesting that activating time exerts important influences on the morphology of activated silica micro-spheres, and also resultant molecular imprinted polymers (MIPs). The absorption capacity and selectivity of the obtained two MIPs were also evaluated for streptomycin and its analogue compounds in water samples. The results illustrate that the streptomycin-imprinted silica micro-spheres (MMIP) exhibited both larger absorption capacity and higher selectivity than those of silica nano-spheres (NMIP). The variant analytical performance might result from inadequate polymerization on the surface of silica nano-spheres.
Evaluation Methods on Adhesion Property between SU-8 Photoresist and Metal Substrate
Authors: Zhang Xiao Lei , Du Li Qun , Wang Ao An
Published: July 2013

During the fabrication process of metal microdevice by SU-8 UV-LIGA technology, due to the poor adhesion strength between SU-8 photoresist and metal substrate it is common for interface separated and bind failure. In this paper pull-off test, scratch test and indentation test were performed to evaluate the adhesion property between SU-8 photoresist and metal substrate, and the feasibility of these three methods was compared. The result shows that the pull-off test fails to evaluate real interface adhesion strength because of the great possibilities of mixed debond appearance which makes the experimental data discrete and inaccurate. The scratch test and the indentation test can efficiently and accurately evaluate the interface adhesion strength between SU-8 photoresist and metal substrate and are demonstrated two preferable methods.
Thermal Assisted UV Digestion Utilizing Nano-TiO2 Photocatalyst for the Detection of Total Phosphorous
Authors: Dong Tian , Tong Jian Hua , Bian Chao , Sun Jizhou Sun , Xia Shan Hong
Published: July 2013

This work presents a novel thermal assisted ultra-violet (UV) photocatalysis oxidation method for total phosphorus (TP) detection. A 365nm wavelength UV light was used as the UV light source, and the TiO2 particles, immobilized on silicon wafer, were used as the catalyst. The sodium glycerophosphate was digested as the typical compound of TP. The digested samples were determined by spectrophotometry after the phosphomolybdenum blue reaction. The catalyst can be used repetitively with long-term stability in this work. For the photocatalysis digestion process under room-temperature, when the reaction time reached 120min, the conversion rates were 92.31% and 93.66% for 1mg/L and 4mg/L of C3H7Na2O6P solutions, respectively. And conversion rates were 95.48% and 99.37% respectively for thermal assisted ultra-violet (UV) photocatalysis digestion process at the condition of 30min and 60°C. Compared with the conventional thermal digestion method and photocatalysis digestion method for TP detection, this thermal assisted UV digestion method can greatly decrease the digestion time and enhance the efficiency.