bluuebunny/crossref_metadata_2025 huggingface dataset:
System Design and Kinematics Simulation of Electrochemical Machining Set-Up for Micro-Holes
Authors: Jiang Jishun , Li Zhiyong
Published: June 2009

Electrochemical micro-machining (EMM) appears to be very promising as a future micro-machining technique, since in many areas of applications, it offers many advantages, which include excellent machining precision and control, high machining rate, perfect surface quality and a wide range of materials that can be machined, regardless of their strength and toughness. At present, electrochemical micro-machining has been applied in the production of some metal workpieces, such as micro-holes, micro-slots and complex 3D surfaces. In this paper, A new electrochemical micro-machining set-up for machining metal micro-holes has been developed. Double level mechanical structure has been applied as the main structure style, which has the advantage of excellent structure rigidity, compact framework dimension as well as perfect maneuverability and maintainability. The control system based on PLC control method has also employed to realize different motion styles for rotating axis, such as uniform velocity rectilinear motion, varying velocity rectilinear motion and cycle rectilinear motion and so on. In order to verify the reliability of this EMM set-up, some test works including static measurement, assembling interferences checking and kinematics simulation have been done. The simulation results demonstrate that the developed EMM set-up for manufacturing metal micro-holes is qualified and can satisfy the technical requirements of electrochemical micro-machining process.
Conceptual Analysis of an Evaporation-Based Micropump Consisting of a Gradient-Capillary Microstructure Surface
Authors: Du Xiao-Ze , Zhao T. S.
Published: June 2009

A novel micropump is proposed for delivering liquid with constant flow rates of 0∼250 nl/s continuously. The liquid is pumped by the surface transpiration in a micro evaporator, which consists of a gradient capillary surface by microfabricating micropost arrays. The micropost arrays are patterned such that the gaps between microposts reduce gradually away from the center microwell to surface edge, by which a capillary force formed to pull the liquid spreading on the evaporator surface. The simple analytical model is proposed to obtain the primary characteristics of the micropump, by which the influences of geometric parameters and the contact angle of fluid on the flow rate, and also the corresponding parameters during the operation of micropump are analyzed in detail. The most striking feature of the micropump is that it can be precisely and simply controlled only by varying the surface wall temperature. A much linear relationship between the flow rate and solid wall temperature can be achieved by the present design. Other features of this novel micropump include its simplicity, no-moving-parts, and ease of controlling the temperature of biological samples. The present micropump concept may be potentially used in delivering a precisely-controlled, continuous flow rate for many new applications in the fields of biotechnology, environmental testing, and instrumentation for analytical chemistry.
Study on the Uniformity of Micro Electroforming Mold Insert Used in Micro Fluidic-Chip Fabrication
Authors: Du Liqun , Liu Haijun , Liu Chong , Zhu Shenmiao , Qin Jiang
Published: June 2009

In the paper, a theoretical investigation was presented, which is used to explain the effect of pulse-reverse current on uniformity in micro-electroforming. And micro-electroforming experiments of two different pulse-reverse currents with gaps in positive direction were carried out correspondingly. The mold inserts used in micro fluidic-chip were micro-electroformed in these experiments, and its feature width is 90um. No backing process was adopted, which mainly consisted of three procedures. Two different pulse-reverse currents used in these experiments were pulse-reverse current with gaps in both positive and negative direction, and pulse-reverse current with gaps only in positive direction, respectively. The fundamental parameters of these experiments were summarized from lots of micro-electroforming experiments of pulse current. After experiments, comparisons were carried out between the results of pulse-reverse current experiments and pulse current experiment. Because negative current could erode the tips on electroforming surface, better uniformity was obtained in these experiments using pulse-reverse currents. The experimental results were consistent with the theoretical investigation.
Jet Electrodeposited Cu-Al2O3 Nanocomposite Coatings
Authors: Chen Jin-Song , Huang Yin-Hui , Liu Zhi-Dong , Tian Zong-Jun
Published: June 2009

A jet electrodeposition device was carried out to prepare Cu-Al2O3 nanocomposite coatings. The influence of the concentration of Al2O3 in the electrolyte and parameters, such as cathodic current density, the electrolyte temperature as well as the electrolyte jet velocity, on the content of the Al2O3 in the deposite were investigated. The coatings ingredient and microstructure was measured by the scanning electron microscope (SEM) with energy dispersive analyzer system (EDX), the microhardness tests were conducted on an microhardness tester. The results show that the jet electrodeposition can fine crystalline particles. The copper deposited layers have nanocrystalline microstructure with grain size of about 50nm. The amount of Al2O3 in composites first increased and then decreased with an increase in the concentration of Al2O3, current density, temperature and jet velocity. The composite with optimum atomic percent of Al2O3 (14.4 at%) can be obtained at the concentration of 30 g/l, cathodic current densities 300 A/dm2, temperature 30°C, and electrolyte jet velocity 8 m/s. The addition of Al2O3 in copper increases the microhardness of the electrodeposited coatings.
A 6-DOF Compliant Joints-Based Precision Parallel Positioner System Driven by Dual Piezoelectric Actuators
Authors: Dong Wei , Du Zhijiang , Sun Lining
Published: June 2009

A precision compliant parallel-structure positioner is presented in this paper, which is dually driven by six piezoelectric motors and six piezoelectric ceramics respectively. This compliant system has a load capacity higher than 2 kg because the parallel mechanism is adopted as the main architecture. This system also can provide larger workspace and higher accuracy simultaneously compared with the conventional compliant positioner systems, because it perfectly integrates two kinds of piezoelectric actuators in one parallel system. The upper platform has the stroke of 10 mm in three linear motion directions and of 6 arc-degrees in three angle motion directions respectively for the adoption of piezoelectric motors as the large motion range actuators. The positioning resolution and repeatability of the upper platform is nanometer scale for the adoption of piezoelectric ceramics as the high precision actuators.
Manufacture and Performance Simulation of a Visible Miniature Loop Heat Pipe
Authors: Qu Yan , Cheng Lin , Luan Tao
Published: June 2009

This paper initiates mechanical machining technique, material processing and thermal science to realize a relative low-cost visual miniature loop heat pipe (mLHP) and simulates the stress distribution and heat transfer characteristics of this mLHP using the softwares MSC-NASTRAN and SINDA/FLUINT respectively. mLHP body is made of stainless steel except the condenser and cooling water jacket which are made of acrylic glass in order to make visualization research inside the mLHP. The sintering wick with good capillary force and enough strength is obtained using the cold pressing sintering method. Both the mechanical stress and the thermal analysis indicate that this new loop heat pipe may meet the design requirements and work well for a heat input up to 40W.
Investigation on Synthesis of Magnetic Fluids Containing Carbon-Coated Iron Nanoparticles
Authors: Liu Tonggang , Bao Jiusheng , Liu Yubin , Yang Zhiyi
Published: June 2009

Oxidation of nanometer metallic particles has been an obstacle that hinders the application of these materials in magnetic fluids. In this paper, the synthesis of magnetic fluids containing carbon-coated iron nanoparticles have been investigated. The carbon-coated iron nanoparticles have been produced by a W-arc discharge method. The uncapsulated particles and carbonaceous debris have been removed from the product by acid treatment and magnetic separation. The morphology, size distribution and phase composition of the particles have been characterized by TEM and XRD. The results show that the size of the particles is about 10 nm, the core of the particles is iron, and the shell of the particles is onion shaped carbon layers. The mineral oil based magnetic fluids containing carbon-coated iron nanoparticles was synthesized by using complex surfactants (T151 and OAE) to form double surfactant layers on the particle surface. The magnetic fluids with highest magnetization was obtained when the amount of surfactants is 160% of that of carbon-coated particles in weight. The magnetic properties of the encapsulated particles and magnetic fluids were investigated by VSM, their magnetization curves show a lack of hysteresis, characteristic of superparamagnetic material. The saturation magnetization of carbon-coated iron particles is 113.9emu/g, and the saturation magnetization of magnetic fluids containing carbon-coated iron particles (35%wt.) is 32emu/g.
Simulation of Rarefied Gas Flow in Microchannel Based on Vorticity-Stream Function Method
Authors: Wei Xueyong , Ward Mike C. L. , Lu Dejiang , Jiang Zhuangde
Published: June 2009

Vorticity-stream function method is successfully used to solve an incompressible gas flow in the parallel-plates micro-channel. A new formula in finite difference scheme is developed to describe the boundary vorticity based on the slip boundary theory and Taylor series expansion. Results show that the boundary vorticity are not only influenced by the Knudsen number (Kn) but also influenced by the tangential momentum accommodation coefficient (TMAC).
Experimental Study on Running-In of Steel Gear Pairs With Micro- and Nano-Materials
Authors: Wang Zegui , Xie Xiaopeng , Zhang Jianhua
Published: June 2009

First, the paper put forward the method of making running-in oils with micro-quartz or nano-diamond powder. Then, the two oils were applied to the running-in of a gear pair respectively. The gears were made of steel C45E4 and by gear shaping. The tooth surfaces of the involute spur gears are fairly rough and soft. These parameters were measured as following: direct-reading and analytical ferrograph of oil samples, electric resistance between the gear pair, oil temperature, 3D-topography and energy spectrum and scan electron image of the tooth surfaces. The results showed that the running-in wear under the micro-oil is much more severer and unstabler than that under the nano-oil. The nano-particles can adsorb and fill into the tooth surface hollows, which improves the surface properties of the metal teeth. The micro-particles mainly form abrasive wear. The running-in wear mechanism of the gear pair under nano- and micro-oils mainly consists of adhesive, oxidative, sliding and abrasive wears. Furthermore, the electric phenomenon, “negative electric resistance”, happened in the running-in wear of the gear pair.
Key Technology of Microelectrode Array Fabrication by Ultrasonic Enhanced Micro-EDM
Authors: Chi Guanxin , Zeng Weiliang , Dong Desheng , Wang Zhenlong
Published: June 2009

Micro electrical discharge machining (EDM), enhanced with ultrasonic vibration, is explored and assessed as a new technology for developing microelectrode array, for microelectrode array fabricated by LIGA has shortcomings such as complex technology and high price. Based on the mechanism of micro-EDM, micro-hole array discharges to fabricate microelectrode array by reverse copying. In the process of reverse copying, the thicker rod electrode can’t rotate, resulting in electric arc and short-circuit easily, so it is necessary to add ultrasonic vibration on the plane plate electrode. According to the technology, a set of micro-EDM system is designed and developed. On the machining system, influence of ultrasonic vibration is analysed from the way of vibration mechanics through theoretical analysis and experimental observation. Compared with machining without ultrasonic vibration, single discharging energy decreases 1/2, discharge frequency improves three times, machining efficiency increases two times and better surface quality is achieved. Finally, 5×5 arrays of microelectrode and microhole made by these microelectrode arrays are got, the diameter of single electrode is less than 30μm and height-to-width aspect ratio is more than 8, moreover these arrays of microelectrode and micro-hole have very good surface quality.
Numerical Investigations of Forced Convection From Rectangular Coiled Pipes
Authors: Conte´ Ibrahima , Peng Xiao-Feng , Yang Zhen
Published: June 2009

Investigations are done to numerically study forced convective heat transfer from the flow inside a rectangular coiled pipe, as micro-scale heat exchange device with staggered arrangement, to the external flow around the pipe. The commercial CFD software Fluent 6.0 is used as the solver. The problems considered were three-dimensional laminar flow of the refrigerant R141B through the tube and turbulent air flow exterior to the tube. The studied coiled pipe was composed of four rows among which two rows were encompassed in a large rectangular coil and the other two were in an inner smaller rectangular coil. The results showed remarkable differences in the flow behavior and heat transfer for different rows of tubes. The secondary flow in the tubes bends of the larger rectangular coil is very weak compared to that of the inner rectangular coil. Better heat transfer process occurred through the tubes of the second row where the higher values of the fluid temperatures were observed in the pipe. The results showed the effects of the straight tubes inclination angle on the flow behavior in rectangular coiled pipes. The shape of the secondary flow is changed from a couple of vortices in the case of smaller angle (α = 9°) to a single vortex in the case of larger angle (α = 45°). The results also showed the rotation of the maximum axial velocity due to the increase in the straight tubes inclination angles. The results are in good agreement with previous numerical and experimental works on laminar flow in helical coil pipe.
Research on the Structure and Performance of Bacterial Magnetic Nanoparticles
Authors: Han Lei , Li Shuangyan , Yang Yong , Zhao Fengmei , Huang Jie , Chang Jin
Published: June 2009

Magnetite nanocrystal has been widely used in many fields. Recently, a new magnetite nanocrystal, called magnetosome, has been found in magnetotactic bacteria. In this article, we researched on the properties of magnetosomes detailedly, such as crystalline, morphology, crystal-size distributions, vitro cytotoxicity, and magnetic properties and quantified primary amino groups on the magnetosomes membrane surface by fluorescamine assay for the first time. From the results, it was clear that magnetosomes have more potential in the biomedical applications than synthetic magnetite.
Preparation and Characterization of Tricolor CdSe-Tagged Microbeads for Bio-Detection
Authors: Chang Jin , Zhang Bingbo , Li Dena , Ma Guiping , Wang Weicai , Zhang Qi
Published: June 2009

Tricolor microbeads for biological assay have been prepared by embedding three quantum dots (cadmium selenide semiconductor nanocrystals) of different size into carboxyl-functionalized polystyrene (PS-COOH) microbeads. These efforts can render CdSe nanocrystals water-solubility, chemical stability and good photostability. The results indicate that QDs-tagged microbeads are highly uniform, reproducible and strong in fluorescence emission. Based on the properties it possesses, QDs-tagged microbead may have great potential for bio-detection.
Synthesis and Characterization of Lysine Modified Chitosan Magnetic Microspheres: A Novel Gene Delivery System
Authors: Li Shuangyan , Hao Lijuan , Yang Yong , Han Lei , Yao Peng , Huang Jie , Chang Jin
Published: June 2009

This paper describes a new formulation of magnetic nanoparticles coated by a novel polymer lysine modified chitosan (CS-lys) as gene carrier. Lysine modified chitosan was synthesized by performing carboxyl of lysine and amido of chitosan in the presence of 1-Ethyl-3-(3-dimethyllaminopropyl) carbodiimide hydrochloride (EDC). The absolute chemistry of the Lysine modified chitosan obtained were characterized using IR and 1H NMR, respectively. The results indicated that many amines of chitosan were modificatied with lysine, and optimized the correlation conditions. The lysine modified chitosan magnetic microspheres were preprated by co-precipitation method. The characterizations of microspheres were measured by TEM, XPS, Dynamic Laser Light Scattering, Vibrating Samples Magnetometer, and X-ray diffraction. The resultes indicated the average particle size was about 100nm and have good superparamagnetic property. The cytotoxicity of CS-lys MNPs was investigated with U293 cells. The results showed that the CS-lys MNPs retained of low toxicity; additionally, combination of DNA and CS-lys MNPs was observed from agarose gel electrophoresis, suggesting that the CS-lys MNPs could be a novel magnetic targeting gene carrier. We also studied the ability of complexes of CS-lys MNPs and DNA crossing BBB in rats by single photon emission computed tomography (SPECT).
A Study of Fine Machining Using Instantaneous Tiny Grinding Wheel Based on Electrorheological Effect
Authors: Feng Jianhua , Yan Qiusheng , Lu Jiabin , Gao Weiqiang
Published: June 2009

The machining effect of different materials electrodes (quenched steel electrode, stainless steel electrode, brass electrode and graphite electrode) and different electrorheological (ER) fluids on the glass was investigated by fine machining experiments using the ER effect instantaneous tiny grinding wheel. Quenched steel electrode and stainless steel electrode can cause bigger and deeper machining region and uniform material removal, while brass electrode and graphite electrode can lead to lower material removal efficiency and nonuniform material removal. The machining trace of zeolite ER fluid is more integrated and deeper apparently than that of SiO2 ER fluid. The processing mechanisms of ER fluid-assisted ultra-precision polishing are analyzed.
Three-Dimensional Discharge Simulation of Inductively Coupled Plasma Etcher
Authors: Cheng Jia , Zhu Yu , Duan Guanghong , Chen Yangying
Published: June 2009

Based on the commercial software, CFD-ACE+, a three-dimensional discharge model of an inductively coupled plasma (ICP) etcher was built. The spatial distributions of the electron temperature and the electron number density (END) of the argon plasma were simulated at 10 mTorr, 200 W and 200 sccm. One-dimensional distribution profiles of the plasma parameters above the wafer’s surface at different pressures and powers were compared. These results demonstrate that the END increases with both pressure and power. And the electron temperature decreases with pressure. The methods and conclusions can be used to provide some reference for the configurations of the chamber and the coil of the ICP equipment design and improvement and process parameters selection.
Analysis of Output Voltages for Piezoelectric Cantilever Generator Based on Vibration Energy Harvesting
Authors: Du Xiaozhen , Chu Jinkui , Wei Shuanghui
Published: June 2009

Low level mechanical vibrations exist in many environments. The primary frequencies can spread about decades and the acceleration amplitudes of the ambient vibrations can be in the range from about 1 to 10 m/s2. Vibration energy harvesting is the promising electric power sources for micro-electric-mechanical system (MEMS). The piezoelectric cantilever model has been proved as a preference structure for vibration energy harvesting. An efficacious computational model of the vibration energy harvesting is established to predict the output of open-circuit voltages in this paper. Meanwhile, a prototype piezoelectric cantilever generator is set up. The calculated results were compared well with that of tests.
Design of an Electroosmotic Micromixer Using CFD
Authors: Wang Xiaozhang , Jiang Zhuangde , Wang Chaohui
Published: June 2009

A numerical computational model of electroosmotic micromixer is developed using a CFD software package, and numerical simulations are executed to verify its accuracy. This rectangular microchannel mixer utilizes heterogeneous surface potential to form recirculation flow and enhance mixing in channel. The basic ζ potential of channel walls is −25mV, and the modulated potentials are +200mV and −200mV, respectively. Several ζ potential modulation modes are studied to optimize the ζ potential modulation, which pattern different modulated ζ potential regions on the top and bottom channel surfaces to produce in-plane vortex. Single-plane (top or bottom) and double-plane (top and bottom) drive vortex are investigated to show their characteristics and influences upon the mixing process. According to the simulation results, a reference entry length indicates that the ratio of entry length to channel width must be greater than one to eliminate the corner effect completely. Mixing process of two kind of modulation arrangements are also compared with the aim of a more effective mixing. In the end an electroosmotic mixer is designed and simulated numerically, which works under a 50000V/m electric field and can get a flowrate about 0.5nL/m with mix length less than one centimeter.
Study on Fabrication and Characterization of Nanometer Scale MIM Tunneling Junction
Authors: Liu Qinggang , Chen Qing , Zhang Chaoyan , Qi Sen , He Botao , Li Dachao , Hu Xiaotang
Published: June 2009

In order to illustrate the effect of the TiOx wires’ characters on the tunneling phenomenon in room temperature and to determine the narrowest TiOx wire as well as its forming conditions which cannot lead to the breakdown of the tunneling junction, the fabrication and tunneling mechanism are analyzed. The TiOx wires with different widths are fabricated by changing the ambient humidity and keeping the scanning speed, oxygen concentration and applied voltage at the same value. The I-V characteristics of tunneling junctions with different width are measured. The results indicate that the narrowest TiOx wire with line width about 16nm can be fabricated between two electrodes of the ultra fast photoconductive switch when the voltage between two electrodes is 6V, which cannot leads to the breakdown of the tunneling junction. It is also found that at room temperature, I-V characteristics of tunneling junctions between two electrodes follows exponential dependence evidently.
Molecular Dynamics Simulation of Non-Fourier Heat Conduction
Authors: Liu Qi-Xin , Jiang Pei-Xue , Xiang Heng
Published: June 2009

Unsteady heat conduction is known to deviate significantly from Fourier’s law when the system time and length scales are within certain temporal and spatial windows of relaxation. Classical molecular dynamics simulations were used to investigate unsteady heat conduction in argon thin films with a sudden temperature increase at one surface to study the non-Fourier heat conduction effects in argon thin films. The studies were conducted with both pure argon films and films with vacancy defects. The temperature profiles in the argon films showed the wave nature of heat propagation. Comparisons of the MD temperature profiles with the temperature profiles from Fourier’s law conduction show that Fourier’s law is not able to predict the temperature development with the time. Different film thicknesses were also studied to illustrate the variation of the time needed for the films to reach steady-state temperature profiles, which means that the relaxation time varies with film thickness.
MD Simulations of Nanoparticle Thermal Conductivity and Nanoscale Thermal Contact Resistance
Authors: Xiang Heng , Jiang Pei-Xue , Liu Qi-Xin
Published: June 2009

The rapid progress and development of the synthesis and processing of materials with structures having nanometer length scales has created a demand for greater scientific understanding of thermal transport in nanoscale devices. Molecular dynamics (MD) simulations are emerging as a powerful tool for studying thermal conductance and phonon scattering in nanoscale objects. A thermal conduction model for spherical nanoparticles was constructed for non-equilibrium molecular dynamic (NEMD) simulations to investigate variations of the nanoparticle thermal conductivity with particle size. The results show that the nanoparticle thermal conductivity is smaller than the bulk value and that of a thin film with a thickness equal to the particle radius for the same boundary conditions. Another thermal conduction model was constructed to investigate the micro thermal contact resistance variations for various contact scenarios. These results show that the thermal contact resistance is a large part of the conduction resistance that decreases with increasing contact area and increases with increasing contact layer thickness.
Fabrication and Characterization of Nanostructured Surface Layer of 38CrSi Steel
Authors: Ma Shi-Ning , Ba De-Ma , Li Chang-Qing , Meng Fan-Jun
Published: June 2009

A nanocrystalline surface layer was fabricated on a 38CrSi Steel with tempered sorbite structure by using Supersonic Fine Particles Bombarding (SFPB). The microstructural evolution of SFPB-treated specimens under different processing conditions was characterized by using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Experimental evidence showed severe plastic deformation and obvious grains refinement were observed and a nanocrystalline surface layer (grain size < 100nm) was found after SFPB treatment. The thickness of nanostructured surface layer varies from a few to about 25μm as treated time increasing from 80s to 240s, but the grain size varies slightly. For the sample treated for 240s, the average grain size of equiaxed nanocrystallites with random crystallographic orientations on the top surface layer is about 16nm. The indexing of diffraction rings indicates nanostructured surface layer consists of ferrite and cementite phases without any evidence of a new phase. The structure size increases gradually from nano-scale to original-scale with an increase of the distance from the top surface layer. In the region about 20–30μm deep from the top surface, the microstructures are mainly composed of 60–100nm roughly equiaxed grains and subgrains. Some subbounsaries are composed of dense dislocation walls (DDWs). In this regime some cell structures are also seen, which are separated by dislocation lines (DTs) and some DDWs. Experimental analysis indicate coarse-grains are gradually refined into nano-sized grains by dislocations activity with gradual increase of strain and strain rate from matrix to treated surface. Both ferrite and cementite phases occur grain refinement. Grain refinement of 38CrSi sample is mainly attributed to the movement of dislocation.
Preparation and Magnetic Properties of the Exchange Coupling NdFeB Nanocomposited Permanent Magnets
Authors: Tian Zongjun , Li Shangdong , Du Youwei , Huang Yinhui
Published: June 2009

The effect of indium additions on the microstructures and magnetic properties of Nd9Fe85−xB6Inx (x = 0–2) nanocomposites prepared by melt spinning was investigated. It was found that a certain amount of indium added to Nd9Fe85B6 magnets enhances the hard magnetic properties. The coercivity and remanence ratio of the magnet with 0.5 at.% indium increases from 405kA/m (no indium) to 465kA/m and from 0.7 to 0.86 respectively. Squareness of its hysteresis loop is also improved greatly. The optimum energy product (BH)max increases remarkably from 95kJ/m3 to 145kJ/m3. The origin for those enhancements is mainly attributed to the magnetically softened grain boundaries and enhanced crystallographical coherency by indium addition. The magnetic annealing is found to be helpful to enhance the coherency and coupling between hard and soft phases.
Experimental Investigation of Loop Heat Pipe With Nano-Ferrofluid
Authors: Chiang T. C. , Chang C. W. , Kuo L. S. , Chen P. H.
Published: June 2009

This study investigated the magnetic effects on the nano-ferrofluid within a closed loop heat pipe (LHP) without any micro-structure. The results show the enhancement of the thermal performance of the LHP can be achieved by setting the magnets properly.
Real-Time In Situ Compensation for Femtosecond Laser Two-Photon 3D Microfabrication
Authors: Gao Guohua , Zhu Yu , Duan Guanghong , Fang Yingxing , Wei Xiaoquan
Published: June 2009

Femtosecond (fs) laser Two-photon Microfabrication is a new real 3D microstructure fabricating method with sub-micron resolution power. In the fabricating process, some factors cause the appearance of the final microstructures different from the design figure. In order to eliminate the appearance error and improve the machining precision, in this paper, two machining defect factors are discussed and real-time in situ compensation is realized based on machine vision monitoring and pattern recognition technique. For the position error induced by the movement error of the 3D micro-displacement scanning stage and the fluid of the liquid resin, one relative distance reference mark system is built to compensate the error. Through the CCD vision monitoring system, at the beginning of every layer fabrication, the 3D scanning stage should be re-posited and ensure the relative positions to the reference marks are right. For the other defect factor, deficient exposure, with the image processing and pattern recognition techniques, the solidified degree of the resin cell can be automatically judged and re-exposure process will be done. This method decreases the accumulative error and is evidently available for the 3D microstructure with larger height value.
Capillary Forces Modeling in Micro/Nano Interactions
Authors: Chang Bo , Wang Jingrong , Zhou Quan , Koivo Heikki
Published: June 2009

This paper introduces two numerical approaches to model the capillary forces under two different initial conditions: given volume of the liquid and under the capillary condensation. The paper thoroughly analyzes the solutions of both numerical methods. Due to multiple numerical solutions may exist for a given set of parameters, criteria based on the derivative and the second derivative of the solution are proposed to determine the existence and stability of those numerical solutions. The features of those numerical solutions are also carefully discussed. Moreover, the results of two numerical methods are compared in different system parameters for several configurations, including two plates with different volume of liquid between them, a plate and a cone of different incline angle, and a plate and spheres of different radius. Suggestions of the applicability of both methods are given based on the results. To allow calculation of capillary forces between arbitrary shaped objects, the paper proposes an early approach to calculate the capillary forces for discretized surfaces.
Investigation on Wire Electrochemical Micro Machining
Authors: Wang Kun , Zhu Di , Qu Ningsong
Published: June 2009

Wire electrochemical micro machining (WEMM) using the online-fabricated micro wire electrode is proposed as a new method of micro machining. Based on electrochemical principle, the mechanism of nanosecond pulses WEMM was investigated. The hardware of the control system was founded using devices of virtual instruments, and the software of the system was designed based on Labwindows/CVI. The micrometer scale wire electrode was online fabricated, the diameter of wire electrode was real-time monitored by precisely measuring the variation in resistance of the electrode, and it is possible that accomplish the fabrication of wire electrode and the following processes continuously in the same machining system. The relations between the machining accuracy and parameters, such as velocity of feed forward and pulses parameters was experimentally studied, and a series of high-aspect-ration micro structure and multi-microgrooves were fabricated. The research of the paper sets up a firm foundation for application of the proposed wire electrochemical micro-machining.
Topological Optimization Design and Manufacture of Microactuator Based on the Nodal Density Method
Authors: Li Zhen , Sun Baoyuan , Qian Min , Zhang Jun
Published: June 2009

In order to improve the situation that the design of microactuator is mostly based on the intuition and experience of researchers, the method of continuum topology optimization using the nodal density is introduced to the conceptual design of microactuator. This new method can ensure C0 continuity of density field in a fixed design domain. The ratio of mutual energy to strain energy of the mechanism is regarded as the objective function, where, the mutual energy and strain energy describe the kinematic function and structural function of microactuator respectively. The final configuration of microactuator is decided on the guide of conceptual design combined with the given working conditions. The finite element method is applied to analysis the transmission ratio and clamping force of microactuator. The prototype of the microactuator is fabricated by using micro-electroforming and SU-8 photolithography techniques and the displacement of the micro actuator is measured by using the stereo vision microscopy. The experimental results show that the properties of the micro actuator can satisfy the designing demands. This topological optimization method based on nodal density plays an important role in guiding the structure design of micro actuator.
Multi-Objective Optimization for a Novel Electrostatic-Feedback Micro-Sensor Based on Genetic Algorithm
Authors: Wang Yongquan , Chen Hualing , Ou Zhiying , He Xueming
Published: June 2009

In this paper, we present the multi-objective optimization for an entire microsystem, a novel capacitive electrostatic feedback accelerometer. From the energy relations of the coupled electrostatic-field, the dynamic model of the system is constructed. Aiming at the global performance, a multi-objective optimization model, where sensitivity, resolution and damping resonant frequency are selected as objectives, is established based on the concept of multidisciplinary design optimization (MDO). Genetic algorithm (GA) is used to solve this problem, and compared with a traditional optimization approach, sequence quadratic programming (SQP). Both the two algorithms can achieve our aim commendably, and the optimal solution given by GA is more satisfied. The research provides us a good foundation to develop the stochastic and implicit parallel properties of GA to obtain Pareto optimal solutions.
Key Factors in Ultraviolet-Curing Wire Saw
Authors: Liu Fuqing , Yao Chunyan , Peng Wei
Published: June 2009

Wire saw, with its ability to cut hard brittle material, such as silicon ingots, crystals and quartz, has emerged as a leading technology for production in semiconductor and photovoltaic industry. There are some defects in conventional loose abrasive wire saw such as significant industrial waste, low machining efficiency, high running costs, etc. As a countermeasure to these problems, some fixed-abrasive diamond wire saws are produced by electroplating process, bonding with resin agent or mechanical embedding of abrasive grains into piano wires. Nevertheless, there still exist disadvantages such as low efficiency of bonding process and high manufacture cost. For this reason, in the research, an idea of making fixed-abrasive diamond wire saw bonded with ultraviolet-curing resin is proposed. In manufacture process, generally, the preparation of materials, improvement of adhesion, and the art of ultraviolet curing determine what technologies is most effective. Therefore, to attain a specific set of properties in the cured wire saw and to achieve an efficient ultraviolet-curing process, the factors that influence the photopolymerization should be well understood. In this paper, the manufacturing process of an ultraviolet-curing resin wire saw is illustrated. Moreover, slicing experiments are deduced to evaluate the results of the study.
Fabrication of Nano-Electromechanical Structures Down to 20 nm by Spacer Technology
Authors: Han Xiang , Xia Ling , Wu Wengang , Yan Guizhen , Xu Jun , Hao Yilong
Published: June 2009

Spacer technology has been developed to fabricate nano-structures for NEMS application. It provides a parallel nano-fabrication method with double or quadplex device density at a certain lithography node. By controlling the deposited film thickness, the feature size of the SiO2 spacer hard mask is reduced down to 35 nm. After the spacer pattern is transferred to Si, a precise thermal oxidation is performed to improve the profile and reduce the plasma damage. Finally, sublimation or HF vapor phase etching is introduced to release the nano-structures according to different structure dimensions. As a result, with better surface morphology, suspended Si nano-beams with a width of 20 nm are obtained. Actuated by mechanical vibration and electrostatic forces, vibrations of the obtained cantilever beams and fixed-fixed beams are observed in SEM. In addition, a metallic nano-nozzle with a diameter of 140 nm is established by electroless plating around the suspended Si nano-beam served as a mold. As a development of the spacer technology, nano-needle array is demonstrated at the cross points of crossed SiO2 spacers by anisotropic etching. The diameters of the hybridized nano-needles are 300 nm so far and can be further reduced by smaller spacer dimension.
The Fabrication of 16*16 MEMS-Based Optical Switch With Accurate Optical Fiber Grooves Integration
Authors: Chen Qinghua , Wu Wengang , Yan Guizhen , Hao Yilong
Published: June 2009

In this paper, a novel surface and bulk hybrid micromachining process for fabricating a 16×16 electrostatically-actuated MEMS-based optical switch is introduced. The fabrication enhances the capabilities of rotation type of micromirrors by enlarging their rotation angle to 90 degrees, which will provide a wide variety of possible mechanical designs for many optical applications such as scanners and filters, especially those requiring large angular adjustment. Furthermore, monolithic integration of fiber grooves and micromirrors are achieved by utilizing accurate photolithography and etching techniques. The fabricated 2-μm-thick polysilicon mirrors are able to rotate inward by 90 degrees to a vertical position when the applied voltage reaches the pull-in value of 208 V. Under the shortest optical path in the 16×16 switch array, the average and worst-case measurement values of fiber-mirror-fiber insertion loss are 2.27 dB and 2.48 dB, respectively. A fatigue test turns out to show that the micromirrors and torsion beams are quite durable to endure more than 1.368×102 billion cycle-tilting movement.
A Predicted Approach for Determining Effective Constants of Fiber Composite With Graded Interphase
Authors: Zhao Jianhui , Ou Zhiying
Published: June 2009

A predicted approach for determining moduli, which include extensional moduli, shear moduli and Poisson’s ratio is presented for fiber composites with graded interphase. The approach is derived based on a mechanics of materials formulations for the concentric cylinder assembles model of a single fiber, surrounding matrix, and a graded interphase to account for the chemical reaction and diffuseness which commonly occurs between fiber and matrix. The principles of the displacement compatibility and force equilibrium for each constitutes of the representative volume element, converted to those of Equivalent Square assembles, are used in the process of the derived predicted approach without complicated computations. The validity of the predicted approach is demonstrated versus comparisons with experimental data and some other models existing in the literature. Synchronously, it shows that determining effective moduli of fiber composite with graded interphase by micromechanics equations is a special case of the predicted approach.
Super-Smooth Grinding Behavior of SiC Ceramics by the Use of Coarse Diamond Grinding Wheel
Authors: Xie J. , Wang S. W.
Published: June 2009

A new super-smooth grinding method for SiC ceramics was proposed by the use of coarse diamond grinding wheel. It can enhance ultra-precision grinding efficiency in comparison with ELID (electrolytic in-process dressing) mirror grinding with super-fine diamond grinding wheel. In grinding, wheel moving direction is vertical to cutting direction different from traditional plunge and traverse grinding and dressing + iron-truing was also employed to protrude and truncate grit cutting edges, improving grit protrusion feature. First, formation of super-smooth ground surface was theoretically analyzed on the base of grit cutting depth and surface roughness. Next, theoretical effect of grinding parameters and grit protrusion parameters on grit cutting depth and surface roughness was discussed. Then, orthogonal experiments were conducted to investigate effect of grinding parameters on surface roughness. Finally, dressing experiment and iron-truing experiment were carried out respectively to investigate ductile-mode mirror grinding behavior in connection with wheel moving speed and grit protrusion feature. Theoretical analysis showed that grit cutting depth and surface roughness depend on wheel rotating speed, wheel moving speed, grit cutting edge number and grit cutting edge angle, but they were not dominated by the depth of cut. Experimental results showed that a super-smooth ground surface can be obtained by decreasing wheel moving speed and improving grit protrusion feature. In addition, the ductile mode grinding may be conducted to realize mirror grinding of SiC ceramics by using wheel moving speed of 5 mm/min and dressing + iron-truing conditions before grinding.
Design of a Micro Tensile Testing Structure to Restrain Non-Axial Alignment Errors
Authors: Zhang Duanqin , Chu Jinkui , Shen Hongyuan
Published: June 2009

Accurate mechanical properties measurements in the micro scale are very important for the design and the fail-safe analysis of MEMS. And the tensile test, as one of the micromechanical experimental techniques, has the advantage of uniform stress and strain fields. In this paper, a new tensile testing structure is presented to solve the non-axial alignment problem in microscale tensile test. The testing structure integrates the specimen and the suspended spring beams on a chip. The function of the additional spring beams is to balance the non-axial loading component and so the specimen is uniaxial tensile. As the spring constant of the tensile specimen in the axial direction is much smaller than the spring constant of the testing structure in the vertical direction, the spring beams could specimen caused by non-axial force. Meanwhile, the spring constant of the specimen in axial direction is much larger than that of the spring beams in the same direction so that the loading shared in the spring beams can be ignored. The performance of the tensile testing structure is confirmed by FE simulations. When the loading force has 2° angle with the axial direction, the stress distribution of the specimen is almost identical with that of under axial loading. The axial stress of the specimen is considerably uniform. That is to say the specimen is uniaxially tensile, although the loading direction is offset the axial. And the force shared in the suspended spring beams is below 3.2% of the loading force. The tensile testing structure could greatly weaken the errors caused by disalignment, and would have big potential to be used in the microscale tensile test.
PZT Film and Si Substrate Two-Layer System Patterning Morphology by Femtosecond Pulsed Laser
Authors: Xiao Shizhou , Guo Rui , Cheng Guanghua , Wu Yalei , Huang Wenhao , Chu Jiaru
Published: June 2009

In this paper, a novel PZT film patterning method by femtosecond laser is proposed. The method is different from traditional dry-etching and wet-etching technology. Femtosecond laser microfabrication technology has several advantages such as high resolution, no mask direct-writing and seldom-heating, etc. A two-layer (PZT thin film and substrate) heating and ablating threshold model is built and the relationship of PZT/Si two-layer system micro ablation morphology depending on laser pulse energy is constructed. From the model and experiment data, we obtain the suitable energy region to pattern PZT film freely without damage Si substrate. A 3μm resolution of PZT pattern is achieved in our experiment. In order to verify the fabrication available of this technology, several micro functional devices are successfully patterned by optimized femtosecond pulsed laser energy and their function are detected. The results prove that the PZT patterning quality is good.
Fabrication of Two-Dimensional Photonic Crystals on N-Type Silicon Substrate Using Holographic and Wet Etching Techniques
Authors: Lin Han , Liu Shou , Zhang Xiangsu
Published: June 2009

Technique of fabricating two-dimensional (2D) photonic crystals (PCs) in silicon wafers using the combination of holographic lithography and wet etching is described in the paper. The fabricated silicon material is suitable to be used as porous silicon for Ge/Si quantum dots growth or other applications. Single exposure holographic method was adopted to fabricate the photoresist mask with the pattern of 2D hexagonal lattice structure. HF:HNO3:CH3COOH = 4:4:3 solution was used to etch circular pores with bowl-shaped bottom into silicon substrate at room temperature with 30 s etching time. Periodic structure in silicon with 1 μm lattice constant and 200 nm pore depth was obtained in the experiment. The fabrication process is fast and cost-effective thus having the potential for industrial mass production of porous silicon.
Opto-Electro-Mechanical Mixed-Signal System-Level Modeling of Micro Deformable Mirror
Authors: He Yang , Jiang Chengyu , Yuan Weizheng , Ma Binghe , Huo Pengfei
Published: June 2009

This paper presents opto-electro-mechanical mixed-signal system-level modeling of micro deformable mirror, the core component of micro adaptive optics system. Micro deformable mirror element was decomposed into functional components and those components were connected to establish a network to represent the real device. Many mirror element models were put together to represent mirror arrays. Then simulations were implemented in just one emulator. The mirror element was decomposed into three kinds of functional components based on this method, i.e. mechanical structure component (beam and mass), electro-mechanical coupling component (electrostatic gap) and optics component (reflective mirror). The mechanical structure behavioral model, the electro-mechanical coupling behavioral model and optical behavioral model could be set up based on the theory of rigid body relative movement and matrix structural analysis, the law of energy conservation and the theory of ray optics and Gaussian beam, respectively. The models were coded in analog hardware description language and a system-level model of micro deformable mirror was established using these models. Electro-mechanical coupling simulations were implemented to find the resonance frequency, the response time and voltage-displacement relationship of the micro deformable mirror element. The frequency analysis results were compared with ANSYS simulations, and the result proved that the method has near FEM accuracy. Then optical phase modulation simulation of micro deformable mirror arrays was implemented to investigate the relationship between input optical signal and output optical signal when control voltage was applied. The simulation result indicated that the mixed-signal system-level simulation of micro deformable mirror could be accomplished rapidly in this way.