bluuebunny/crossref_metadata_2025 huggingface dataset:
A Power Flow Analysis and Control Methodology for Cycloid Gear Train in Precision Transmission
Authors: Xu Wujiao , Fu Yu , Du R.
Published: June 2009

Cycloid gear is a special type of gear used in precision transmission system. For example, the mechanical watch movement requires not involute gear train but cycloid gear train owing to the very small size and large transmission ratio, in which the gear modules vary from 0.12mm to 0.0625mm and the maximum transmission ratio is 12. As we all know, the mechanical watch is a precise machine and the power transfer in the watch main train should be kept stable for the timekeeping performance. A three dimensional (3D) model of gear main train system, which includes all the gears, pinions and escapement, is developed. The multi-body dynamic simulation technique is utilized to analyze the influence of torque transmission fluctuation in the cycloid gear train on the vibration cycle of escapement in detail. In practical meshing condition, the misalignment errors are inevitable, the influence of which is obvious due to the gear module in main train is very small. All possible misalignment errors in cycloid gear train are analyzed in the analysis model. Algorithm for computing torque transmission (power flow) is presented, which is directly based on multi-body simulation result and is different from other approximation methods. Thus with the influence of misalignment errors, the variance of torque transmission is calculated. For reducing the cycloid gear train’s sensitivity to misalignment errors and achieving the precision transmission, the combined wheel tooth modification approach is put forward, i.e. wheel tooth modification in profile direction and in longitudinal direction. It could be seen clearly that with the combined wheel tooth modification, the fluctuation of torque transmission in the cycloid gear train is decreased and the transmission efficiency is improved.
Design and Test of Small-Scale Rotary Engine Power System
Authors: Liu Yisheng , Li Wei , Yang Canjun , Song Ruiyin
Published: June 2009

In order to develop a portable, autonomous power generation system with a magnitude improvement in energy density over alkaline or lithium-ion batteries, the liquid hydrocarbons fueled small-scale rotary (Wankel-type) internal combustion engines project is directed toward the development of a practical small-scale power generator. Micro combustion and seal are two of the most prominent questions of the design of small-scale rotary engine. As a result, the mathematical model of the micro combustion is proposed and some simulations are implemented. In addition, a combustion experiment is made in a micro combustion vessel to confirm the lower limit of the combustor size and quench distance. Based on an epitrochoidal-shaped housing the small-scale rotary engine is designed. For its planar construction, the rotary engine is available to the MEMS manufacturing techniques such as DRIE, LIGA, DEM, EDM, and is also suitable for micromation. While in the experiment, it is founded that with the housing of the engine with epitrochoidal-shape expanding, the engine couldn’t work steadily. Thus the analysis and simulation of heat transfer and thermal-stress are made to modify the contour of the epitrochoidal-shaped housing. Besides, the single-rotor construction, oil film face seals, and springs apex seals are adopted in the design. A series of small-scale rotary engines (including M2.4, M1.5 and M0.75 rotary engine) have been designed and fabricated from steel by using electro discharge machining (EDM). Test platforms for small-scale rotary engines have been developed and experiments have been conducted respectively, in which liquid hydrocarbons fueled small-scale rotary engines and high-pressure air driven small scale rotary engines to examine the effects of sealing, ignition, design, and thermal management on efficiency. The preliminary test of the M2.4 rotary engine (compressed chambers is 166 mm3, swept displacements is 2600 mm3) fueled by liquid hydrocarbons has shown steady 150 W net power output at 15000 RPM. The preliminary test of the M0.75 rotary engine (compressed chambers is 9 mm3, swept displacements is 143 mm3) can output 1.5W net power at 14000 RPM with high-pressure-air driven. Testing of the small-scale rotary engine has verified the feasibility of the micro-engine. However, heat loss and sealing issues are the key points for efficient operation of the micro-engine, and they must be taken into account in its design and fabrication to improve the design of sealing and micro combustion chamber.
A Prediction Method for Thermal Conductivity and Electric Conductivity of Nanofluids Based on Particles Aggregation Theory
Authors: Ding Guo-Liang , Jiang Wei-Ting , Gao Yi-Feng
Published: June 2009

Nanoparticles in nanofluids are in the form of nanoparticle clusters caused by aggregation. In order to calculate the thermal and electric conductivities of the nanofluids, the growth process and three-dimensional space structure of the nanoparticle cluster in the host fluid was simulated, and then the thermal and electric conductivities of the cluster were calculated with the resistance network method. The thermal and electric conductivities of the nanofluid were calculated based on the simulated thermal and electric conductivities of nanoparticle clusters, the volume fraction of nanoparticle clusters to the nanofluid as well as the liquid molecule adsorption layer of the nanoparticle. The simulation method was validated by experimental data.
A Study on Micro Strain Electrorheological Damper Model
Authors: Chen Yaying , Zhu Yu , Duan Guanghong , Cheng Jia
Published: June 2009

This paper presents experimental and theoretical model analysis of an electrorheological damper operating in the micro strain state. An ER shear damper is developed and installed on an established ultra-precision gas bearing stage system. The damper characteristics of force vs. velocity responses under various electric fields and excitation frequencies are obtained. To describe the practical damper characteristics, a modified Eyring-plastic model is proposed, which differ from the original Eyring-plastic model by adding a constant term. The constant term can compensate the curve error induced by the width change of the pre-yield hysteresis loop. Based on optimal parameters identification, the modified Eyring-plastic model fits the experimental data more closely. So it is more accurate to express the electrorheological shear damper characteristics operating in the region of micro strain.
A Robust Multiscale Algorithm for Motion Measurement With High Accuracy
Authors: Lu Qinghua , Zhang Xianmin
Published: June 2009

The computer micro-vision technique plays a vital role in many existing methods of motion measurement in precision engineering, which its measurement accuracy and speed perform very well. Gradient-based techniques represent a very popular class of approaches to measuring motions. A robust multiscale algorithm of hierarchical estimation for gradient-based motion estimation is proposed in this paper using a combination of robust statistical method and multiscale technique. In such a multiscale approach of hierarchical estimation, motion at each level of the pyramid is estimated using different gradient filters. The iterative multiscale estimation begins by using 5-tap Central filter, and it is switched to 9-tap Timoner filter after a few iterations. In addition, robust M-estimators are applied at each level of the pyramid in order to overcome the problem of the outliers caused by illumination variations and motion discontinuities in motion estimates. Experimental simulations show that the new algorithm not only provides an improvement in estimator accuracy, but also achieves computational speedups for motion measurement of MEMS image.
Humidity Sensor Based on Polymer Coated Quartz Crystal Microbalance (QCM)
Authors: Ying Zhihua , Jiang Yadong , Xie Guangzhong , Du Xiaosong , Wang Hua , Yu Junsheng
Published: June 2009

Humidity sensors featured by the combination of a quartz crystal microbalance (QCM) and polyvinylpyrrolidone (PVP) film were fabricated. PVP films were distributed onto the electrode surfaces of quartz crystal by drop-coating. The electrical characteristics of the devices as a function of relative humidity (RH %) measured in the airtight testing chamber to generate the controlled humidity were tested. The change in frequency of QCM with sensitive film was in situ monitored. Result shows when the polymer-coated QCM exposed to certain humidity circumstance, the change of mass on crystal sensitive surface results in the decrease of resonant frequency. It was found that the increase of shift frequency is proportional to the thickness of polymeric film. In low humidity range less than 50% RH, all of the sensors showed linear characteristics to humidity and mild frequency shift. In high humidity, the frequency shift changed dramatically.
Slurry Flow in CMP Considering the Pad Roughness and Porosity
Authors: Zhang Chaohui , Ye Wei
Published: June 2009

Chemical mechanical polishing (CMP) is a widely adopted technique to achieve high level of global and local planarity required in modern integrate circuit (IC) industries and hard disk manufacturing process, etc., wherein the slurry flow weighs heavily on the performance. The pad surface will alter the flow features considerably. A preliminary wafer-scale flow model for CMP is presented considering the roughness as well as the porosity of the pad. Numerical simulations were conducted to show the slurry flow features. The results show that the porosity of the pad is conducive to slurry delivering, and small porous parameter will lead to prominent increase of load capability, accounting for larger material removal rate. The rough surface carries additional fluid in the valleys of the polishing pad thereby provide some chemical reactions. The model predictions will be conducive to the removal rate and mass transport computation. This will shed lights on the mechanism of CMP process, which is for a long time considered as a difficult circle to square.
Investigation of Microstructure and Properties of Ni/CNT Nanocrystalline Coating Deposited by Brush Plating
Authors: Tan Jun , Yu Tiantian , Xu Binshi , Zhu Bin
Published: June 2009

Nickle-carbon nanotube (Ni/CNT) nanocrystalline coatings with different parameter were prepared by brush plating. The carbon nanotubes were added into common nickel solution for brush plating and ball milling was used to disperse the carbon nanotubes in the solusion. The concentration of carbon nanotubes in the solution was 3 g/l. The SEM and XRD were applied to investigate the grain size, microstructure and morphology of the coatings. The hardness and the wear mass loss of the coatings were examined on micro hardness tester and ball on disk tribotester. The results show that under a direct-current source, the grain size of the Ni/CNT coating was about 20 nm. Under a pulse-current source, the grain size of the Ni/CNT coatings decreased and the coatings gained smoother surface when the pulse-width became shorter. The grain size of the Ni/CNT coating increased with the heating temperature increasing and the average grain size of the coating heated at 500 degrees centigrade was over 50 nm. The microhardness of the Ni/CNT coating under a pulse-current source was higher than that of the coating under a direct-current source. Under a pulse-current source, the microhardness of the Ni/CNT coating increased when the pulse-width became shorter. The microhardness of the Ni/CNT coating changed slightly below 300 degrees centigrade, while decreased obviously after heated up to 400 degrees centigrade. The wear resistance of the Ni/CNT coating under a pulse-current was higher than that of the coating under a direct-current. Under a pulse-current, the wear resistance of the Ni/CNT coating increased when the pulse-width became shorter.
Simulation on Dynamic Characteristics of Micro Magnetic Acceleration Switch Based on Finite Element Method
Authors: Zhu Ying-Min , Huang Chun-Yue , Jia Jian-Yuan , Fan Kang-Qi
Published: June 2009

According to the characteristic that the force between a permanent magnetic couple changes nonlinearly with the magnetic displacement, a novel micro acceleration switch of permanent magnetic force is designed. The stiffness of the beam suspension, the module mass in the micro switch, and the magnetic force of the permanent magnet couple are selected as the major structure parameters and nine acceleration switches with every kind of combinations of the structure parameters were designed by using an orthogonal array. A Finite Element Method (FEM) model is built to simulate the contact force between the module and the contactors and the operation of the nine switches under a preset excitation wave of the environmental acceleration. The first 6 order natural frequencies and the vibration modals of the micro acceleration switch are obtained. The range analysis is given based on the simulation results of the contact forces. The results reveal that, in the three major structure parameters, the stiffness of the beam suspension W affects the electrical contact reliability the best with the permanent magnetic force F secondly and the mass G the least. The combination of structure factors that results in the best electrical reliability is W1G2F2, namely, the beam suspension stiffness W of 2134N/m, the module mass of 1.99g and the permanent magnetic force of 0.21N.
A Study on the Flow Characteristics of the Nano Fountain-Pen Using Membrane Pumping
Authors: Lee J.-H. , Kim H.-M. , Kim Youn J.
Published: June 2009

Atomic force microscope (AFM) probe was developed for the application of dip-pen nanolithography (DPN), which is capable of surface patterning. But, the current lithography process is not performed constantly and the patterning takes a long time. In this paper, the flow characteristic of a novel-designed nano fountain-pen is investigated to make the constant patterning in micro process using active membrane pumping. It is composed of reservoir, micro channels, tip and chamber. The reservoir is linked to micro channels embedded in a V-shaped cantilever. Micro channels transport water or ink from a reservoir to substrate, realizing continuous writing at the nano scale. This so-called the fountain-pen nanolithography (FPN) device allows continuous fluid supply for different localized applications. The liquid can be certainly and exactly injected with membrane pumping. Using a commercial code, FLUENT, the velocity and pressure and flow rate are obtained under laminar, unsteady and three-dimensional incompressible flow with no-slip condition, and results are graphically depicted.
A Diffusion-Based Approach for Nanobead Drag Forces
Authors: Sirk Timothy W. , Brown Eugene F.
Published: June 2009

A central process of the Bead ARray Counter (BARC) biosensor involves propelling a dilute solution of streptavidin-coated micron-scale beads through water. It is desirable to downsize these beads, leading to a basic engineering problem: What is the drag force acting on a nanoscale bead having an unknown hydrodynamic boundary condition? We use molecular dynamics simulation to estimate the drag force acting on a hypothetical biosensor “nanobead” without assuming a no-slip condition or a user-supplied slip parameter.
Development of Double Equipotential Ring Capacitance Sensor in Ultra-Precise Optical Measurement
Authors: Zhang Jianhuan , Gao Xuemin , Yang Xiaodong
Published: June 2009

Measurements based on all sorts of optical methods in mechanical engineering area had been extensively studied, and in these measurements, many sensors, such as capacitance, are often applied to detect the focusing displacement of objective. For improving the edge effect of the plate capacitance, an equipotential ring is applied. Following the Abbe rule, a plate capacitance sensor with double equipotential rings and a central hole is introduced. The axis of the optical system perforates through the hole of the sensor, thus no Abbe error occurs. If the capacitance sensor is manufactured with machine tools, the gap between the equipotential ring and the orbicular electrode can not be narrow enough, meanwhile, the assembly becomes difficulty. In order to get narrow gap as well as thin electrodes, PCB process is tried to make the capacitance electrodes, but the gap between the equipotential ring and the electrode can only be about 0.1mm. When MEMS technique is introduced, the gap can be about 2μm. Although the cost is by far the higher than that made with PCB, the linear error as well as the measurement accuracy can be promoted greatly. After the circuit is designed, test of the capacitance sensor made with MEMS is completed, and the result that linear error is less than 0.05% and the sensitivity is 1mV/nm is presented with displacement of 30μm.
Research on Mechanism of Ultra-Precision Electrical Discharge Grinding for Engineering Ceramics
Authors: Yu Lili , Liu Yonghong , Zhu Lianzhang , Ji Renjie , Li Xiaopeng
Published: June 2009

Mechanism of the ultra-precision electrical discharge grinding for engineering ceramics is analyzed according to heat source and heat partition. The heat source and heat partition models are established and the numerical calculation is carried on. Two different heat sources have been developed due to the dissimilarity between the grinding heat source and the EDM heat source. The heat of the grinding is mainly made up of ploughing and slipping, while Gaussian heat distribution has been considered due to EDM. Heat model of ultra-precision electrical discharge grinding for engineering ceramics is obtained by using superposition. The heat partition model among engineering ceramics, grinding wheel and dielectric fluid is developed based on temperature field theories and the numerical calculation is carried on. The results show the heat partition varies inside the electrical discharge grinding zone. The grinding wheel and water-based dielectric fluid take away most of the heat, thus can help to get a good surface integrity of engineering ceramics.
Molecular Dynamics Study of Wetting on Brushlike Nanopillar and Wavelike Nanorough Surfaces
Authors: Suciu Claudiu Valentin
Published: June 2009

A Molecular Dynamics technique is proposed to simulate the motion of water nano-droplets on brushlike nanopillar and wavelike nanorough surfaces. Firstly, a brushlike nanopillar structure is obtained by deposition of a hexagonal packing of alkyl linear chains CnH2n+1 (n = 1–18) on a (0001) type flat surface, consisted of hexagonal packed carbon atoms. Distance between the grafted alkyl chains is selected in the 0.5–1.4 nm range, and the distance between the carbon atoms of the base surface is set to 0.1421nm. Next, the (0001) type flat surface is folded in order to obtain a wavelike nano-roughness. Water cluster is consisted of 729–2197 molecules, and after 25ps it reaches a diameter of 3–5 nm, which corresponds to a liquid phase of 1g/cm3 density, at an equilibrium temperature of 293K. Lennard-Jones potential is used to describe all the interactions into the considered system. By the appropriate input of the Lennard-Jones parameters one controls the hydrophilic level of the base surface. Influences of the intermolecular distance and the length of the grafted alkyls, as well as the influences of the nano-wavelength and the hydrophilic level of the base surface on the contact angle are illustrated. Such results are useful for the appropriate design of ultrahydrophobic nano-surfaces, and for the optimal design of nanoporous materials, able to produce surface dissipation of the mechanical energy.
Fabrication of AFM Single-Walled Carbon Nanotube Tips
Authors: Wang Rui , Xu Hua-Ming , Gong Qian-Ming , Liang Ji
Published: June 2009

Probe is a key part of atomic force microscopy (AFM) and the curvature radius of its tip limits the lateral resolution. Furthermore, as an expendable, its life has a direct effect on operation cost. Single-walled carbon nanotubes (SWNTs) are ideal materials for the probe tips used in atomic force microscopy (AFM), since they have intrinsically small diameters, high aspect ratios and unique wearability. Herein, the fabrication of AFM SWNT tips is systemically investigated, including mechanical method and direct growth method. In the former, substrates with isolated SWNTs are first prepared by chemical vapor deposition and then scanned with conventional silicon probes under AFM. During scanning, SWNTs can be picked up from substrates and attached to the pyramid of silicon probes via attractive Van del Waals forces. Preparation of substrates is decisive to this method, since only the SWNTs disengaged from surface are possible to pick up. Different substrates have been compared and the results show that the substrates full of gaps are prior to the planar ones. SWNTs are suspended across gaps and suitable to the following assembly. The mechanical method is easily implemented and can produce AFM SWNT tips one by one, while the direct growth method is promising to manufacture them in a large scale, in spite of more difficulty. In the latter, catalyst for the growth of SWNTs is directly placed on individual commercial probes or pyramid arrays. Through chemical vapor deposition, grown SWNTs protrude from the original tips and create new ones. Due to the random orientation of SWNT growth, the yield of successful SWNT tips is generally low for the direct growth method. In this article, Electric filed is used to direct the growth orientation of SWNTs during chemical vapor deposition. Both electrodes are located in the furnace to apply a static electric field along the pyramid axis during growth. The intensity can be varied from 0.1V/um to IV/um, and the direction is towards the surface of wafers. The growth of SWNTs is oriented by electric field and the yield of SWNT tips is raised. The AFM SWNT tips derived from the above two methods have been utilized to image Au layers in the tapping mode. Compared with conventional silicon probes, SWNT tips are longer lasting to keep a high resolution.
Laser Sintering of Nano-Al2O3 Powders on Plasma Sprayed Ceramic Based Coatings
Authors: Shen Lida , Huang Yinhui , Tian Zongjun , Hua Guoran
Published: June 2009

This paper describes an investigation of nano-Al2O3 powders reinforced ceramic coatings, which has included NiCrAl and Al2O3+13%wt.TiO2 coats pre-produced by atmosphere plasma spraying, implemented by laser sintering. Commercial NiCrAl powders were plasma sprayed onto 45 Steel substrates to give a bond coat with thickness of ∼100μm. The 600μm thick Al2O3+13%wt.TiO2 based coating was also plasma sprayed on top of the NiCrAl bond coat. With 2.5kw continuous wave CO2 laser, nano-Al2O3 ceramic powders were laser sintered on the based Coatings. The micro structure and chemical composition of the modified Al2O3+13%wt.TiO2 coatings were analyzed by such detection devices as scanning electronic microscope (SEM) and x-ray diffraction (XRD). Microhardness, wear resistance and corrosion resistance of the modified coatings were also tested and compared with that of the unmodified. The results show that the crystal grain size of Al2O3 had no obvious growth. In addition, due to the nanostructured Al2O3 ceramic phases, the coatings exhibited higher microhardness, better wear resistance and corrosion resistance than those unmodified counterparts. The complex process of plasma spraying with laser sintering as a potential effective way of the application of ceramic nano materials was also simply discussed and summarized in the end.
Mechanism Analysis and System Identification of the Quadrature Error in MEMS Gyroscope
Authors: Yang Jun , Gao ZhongYu , Zhang Rong , Chen ZhiYong , Zhou Bin
Published: June 2009

This paper discusses error mechanism and experimental system identification of the quadrature error present in Tsinghua University MEMS vibratory rate gyroscopes. The magnitude and stability of the quadrature error are both of concern because they corrupt the measurement of the actual input rate. The stiffness matrix of suspension beams and a three-mode dynamics model of gyroscope structure are developed and the analysis demonstrates that structure imperfections result in the quadrature error, which is generally considerably larger than Coriolis-induced rate signal. The gyroscope dynamics and structure parameters are identified by modal experiment and frequency response function matrix. The experiment results from twenty gyroscope samples demonstrate that structure imperfections are main reasons resulting in the quadrature bias of the gyroscope, including anis-elasticity of suspension beams, and stiffness coupling between drive axis and sense axis. The identified structure parameters will also contribute to future laser trimming for reducing the quadrature error of gyroscope.
A Universal Interface Circuit for Capacitive Vibratory Microgyroscopes
Authors: Jiang Qinghua , Yuan Weizheng , Chang Honglong
Published: June 2009

In widely used closed-loop drive scheme for capacitive vibratory microgyroscopes, additional capacitive interfaces for monitoring of the drive mode is avoidless. In addition, capacitive interfaces for tuning the resonance frequency of microgyroscopes is also necessary for closed-loop detection. Introducing these additional capacitive interfaces, the sense capacitances became much smaller, and the efficiency of the driving became lower. Correspondingly the sensitivity of the capacitive vibratory microgyroscopes decayed. This paper presents a universal and simple interface circuit without these additional capacitive interfaces. One single-ended bridge is formed by a pair of drive capacitors and sense capacitors. The vibrating mass, as the output of the bridge, is held at virtual ground by a charge integrator. Drive voltage combined with high-frequency carriers is applied to fixed node of the drive capacitors. High-frequency carriers with offset which are used as feedback force are applied to fixed node of the sense capacitors. Thus output of the integrator includes modulated driving, sensing mode signals and the drive voltage. Due to the high Q of the microgyroscopes, the carriers have no impact on the drive mode. And the frequency of the drive voltage is usually much lower than the carriers, so a low pass filter can be used to eliminate the influence of the drive voltage on the integrator. The two carriers have different frequencies, and the band pass filters can be used to separate the modulated driving and sensing mode signals. Using two capacitive vibratory microgyroscopes with different structures and capacitive interfaces, the experiments were respectively carried out. The results indicated that the 1/f noise was effectively reduced, (and) the couplings of the driving ()on sensing signal was eliminated. The circuit can resolve variations of input capacitance less than 1fF.
Micromachined Pressure Sensor Based on GaAs/AlAs/InxGa1−xAs Resonant Tunneling Effect
Authors: Zhang Wendong , Wang Jian , Xue Chenyang , Xiong Jijun , Liu Jun , Tong Zhaomin
Published: June 2009

This paper reports a novel micromachined pressure sensor based on GaAs/AlAs/InxGa1−xAs resonant tunneling effect. The 20 μm×20 μm GaAs/AlAs/InxGa1−xAs resonant tunneling structure (RTS) is incorporated in a 7 μm-thick, 740 μm-diameter GaAs circular membrane and the fabrication technology of the membrane is based upon the micromachined control holes technology. The pressure sensor is packaged hermetically, and the experimental results show that the current-voltage characteristic of RTS is a function of the external pressure, and the resonance peak voltage is linearly dependent on the pressure, the linear sensitivity is up to 0.37mV/KPa.
Micro Ablation of Optical Fibers Using Vacuum Ultraviolet Laser
Authors: Dai Yutang , Li Weilai , Jiang Desheng
Published: June 2009

157nm vacuum ultraviolet laser was considered as one of promising tools for next-generation lithography or precision micro-ablation. In this study, a multi-functional micro-ablation system with 157 nm vacuum ultraviolet laser was conducted. Some laser ablation experiments were performed for silica glasses and optical fibers. For the silica glasses, the average ablation rate of the 157nm laser could reach to 4μm/s. The material removal is one-photon-absorption process in the case of 157nm VUV laser. Experiments also show that, the 157nm laser ablation has wonderful possibilities for fabricating precision 3D micro-structures in the optical fibers.
Study of Molecular Dynamics Simulation of Deposition in Air in Micro EDM
Authors: Wang Zhenlong , Cui Jingzhi
Published: June 2009

In this paper, a model of disposition in gas was built, Verlet arithmetic of molecular dynamics (MD) computer simulation method was carried out to simulate molecular movement during deposition process. In deposition experiments, we find that as discharge current or discharge duration increases, single discharge energy increase, correspondingly the deposited granule’s size and deposition velocity both increase. However when discharge current increase to a certain value (13A),or discharge duration increase to a certain degree (>4μs), single discharge energy will be too high that the electrode is easy to burn, so the deposition velocity decreases, deposition even be failure. From the simulation results we find the same law. Simulation rsults show that the relation of emitting velocity to deposition velocity and relation of discharge electric field to deposition velocity of the simulation results are accordant to the trend of deposition velocity to discharge current and discharge duration in experiment. This research provides the reliable theoretical basis for further experimental study on the processing law of deposition and three dimensional deposition in air in Micro EDM.
Fabrication and Test of PECVD SiC Resonator
Authors: Wang Yu , Guo Hui , Zhang Haixia , Zhang Guobing , Li Zhihong
Published: June 2009

This paper utilized SiC thin film deposited by low temperature PECVD to fabricate resonator at 300°C, following by annealing and doping to release its stress and improve its electronics contact. The test results show that, the frequency of PECVD SiC resonator is among 60–150KHz. The Q value of resonator was estimated according to the tested frequency-amplitude curve, is about 10±3. The ability of SiC resonators in erosion environment was also studied, under 5mins etching in KOH solution, the whole structure are kept very well. Therefore, this kind PECVD SiC resonator not only can be used widely in harsh environment, such as, high temperature, erosion and high pressure, but also can integrated with CMOS process, release the integration manufacturing of circuit and devices in micro-scale.
Fast Mixing of the Ferrofluid in Microchannels
Authors: Chang C. W. , Tsai T. H. , Chiang T. C. , Wang P. Y. , Hsieh Y. F. , Chang C. H. , Chen P. H.
Published: June 2009

The mixing of the ferrofluid in microfluidic chips was investigated in this study. Mixing processes of the ferrofluid in the presence of a permanent magnet are highly different from that of pure diffusion. The magnetic field re-distributes the ferrofluid and the mixing efficiencies vary with the positions of the magnet and the volumetric flow rates of the fluids. With the suitable setup of the magnet, the mixing efficiencies can reach more than 90% within one characterisitic width of the channel. By the suitable design of the microfluidic chips and the proper position of the magnet, the efficient mixing of the ferrofluid in PDMS microfluidic chips can be performed.
A Si3N4 Tube Formed Using TMAH Etching
Authors: Chen Huijun , Zhang Dacheng
Published: June 2009

In this paper, micro-tube fabricated from SiO2/Si3N4 strained composite structures using a self-scrolling procedure is presented. This fabrication is a self-organization process using stress of bifilm. This technique is based on self-rolling of a thin highly strained SiO2/ Si3N4 bifilm detached from the substrate by TMAH selective etching. The material of bifilm and the solution for anisotropic etching are in common use, so this method can be widely used in the future.
Finite Element and Experimental Analysis on Micro-Vibration of Ultra Precision Air Bearing Linear Motion Stage and Methods of Its Elimination
Authors: Zhang Ming , Zhu Yu , Ren Gexue , Duan Guanghong , Gao Guohua
Published: June 2009

Air bearing linear motion stages with high speed and ultra high positioning performances are always used in steppers or scanners which are the most important equipments in microlithography process. Excellent air bearing design is one of the keys to archive those performances. Good load capacity and stiffness are always the main design objective for designers. But experiment shows that air bearing stage with high stiffness and load capacity may suffer from micro vibration. The micro vibration is not the “pneumatic hammer” which usually happens to air bearing due to poor restrictor design. Its amplitude ranges from tens to hundreds of nanometers and frequency from tens to thousands of Hz. For an ultra precision linear motion stage which positioning accuracy level is about ten nanometers, the vibration amplitude is obviously unacceptable. Further more, the micro-vibration seriously lower system’s dynamic characteristics. To find the reason of micro-vibration, finite element method is used to analyze the air flow in the air channel of air bearing. The result shows that the turbulence flow in the air channel will induce the micro-vibration. So the laminar flow in the air channel is the key way to eliminate the micro-vibration of air bearing stage. To turn the turbulence flow into laminar flow, the designer must consider the radius of the air channel, the number of air inlet and mass flow rate of air bearing comprehensively.
Application of Nanometer TiO2 Photocatalysis Material in Air Purification
Authors: Hou Haiyan , Zhu Dongsheng , Cheng Jun
Published: June 2009

The production of oil mist in machinery processing workshop is harmful. To control concentration of oil mist, the TiO2 which can treat with manifold organic pollutants is used to purify oil mist. At first, the nanometer TiO2 is prepared using the sol-gel method on the optimum formulation that showed a higher activity. Then it is treated by dip-coating technique using the non-woven fabric as composite support. The efficiency of suppression of oil mist is compared with ordinary materials. With the increase of time, the purification of the nanometer TiO2 photocatalyst sieve against oil mist of non-woven fabric is investigated in solar radiation at room temperature. It oxidizes pollutants of oil mist to CO2 and H2O. The experiments demonstrat oil mist is oxidized on the TiO2 sol at the 22nd minute with a maximum capacity of 0.3219g. It infers from the experiments the photodegradation effect is high and the reaction is fast. It also concludes that the nanometer TiO2 photocatalysis material is an ideal material for suppressing oil mist in air. At last, a status the application of technology in air purification as well as its problems and trends are presented. The technique has a promising prospect to solve the increasing air problem of the workshop.
Research on the Fabrication Time and Surface Quality of the Plane Model in the Two-Photon Three Dimension Microfabrication
Authors: Wei Peng , Zhu Yu , Duan Guanghong
Published: June 2009

The comprehensive evaluation index was introduced to reduce the fabrication time and improve the surface quality of the two-photon three dimension microfabrication. And the relation between the exposure time and the overlap rate with the fabrication time and the surface quality was described in detail. The objective function based on the evaluation index was given. And the Genetic Algorithm was applied in searching the optimal solution of the objective function. Simulation results indicate that the method is useful to some extent.
Servo Scanning EDM for 3D Micro Structures
Authors: Li Yong , Tong Hao , Cui Jing , Wang Yang
Published: June 2009

In electro discharge machining (EDM) for 3D micro structures, the electrode wear is serious and it needs to be compensated in process. To obtain a better balance of the machining accuracy and efficiency, a servo scanning EDM method is proposed for 3D micro structures, in which the electrode wear is compensated on real-time by controlling the discharge gap constant. It is supposed reasonably that the machining depth of each layer in servo scanning EDM is consistent if discharge gap is kept preferably. The servo scanning EDM strategies include the model design by Pro/Engineer (Pro/E), the plan and simulation of scanning path, and the machining process. The 3D micro structures are machined by scanning layer-by-layer under servo control of the electrode with monitoring discharge gap signal. The CAM, gap servo control, and real-time electrode wear compensating are integrated into the machining system. The evaluation experiments of servo scanning EDM and the typical machining experiments of 3D micro structures have been carried out. The machining results show that the electro discharge in the servo scanning EDM is more stable. Servo scanning micro EDM is propitious to improve machining accuracy and efficiency in 3D micro structures.
Numerical Simulation of Micro Air Vehicles With Membrane Wings
Authors: Zhang Xiaoqin , Tian Ling
Published: June 2009

Micro Air Vehicles (MAVs) have advantages of small size, low cost, flexibility and controllability etc., so they will be applied widely in military and civilian fields. They have obviously low Reynolds number aerodynamics, which is different from traditional aircrafts. In this paper, numerical simulation based on fluid-structure interaction for flexible wing MAVs is presented. Flexible wings are composed of carbon frames and covered with membrane skins. Because flexible wing MAVs easily deform in airflow, both structure model and fluid model should be built. The two models are connected by interfaces of membrane wings, which transmit distributed pressure and deformations of membrane wings. When membrane wings are located in airflow, they will deform with actions of surrounding airflow. Deformation of membrane wings also affects airflow and pressure distributed on the wings’ surfaces will also be changed relatively, which will compel the shape of membrane wings to be changed once more. Therefore, numerical simulation of flexible wing MAVs is not only the analysis of fluid field, but also the structure deformation effects. Navier-Stokes Equations are nonlinear and complicated, so direct interaction of fluid and structure equations is rather difficult and costs too much time. Indirect interaction method is more feasible and it is adopted in this paper. Structure deformation and distributed pressure on membrane wings surfaces are calculated separately, and then pressure distribution from fluid solver is transmitted to structure solver. After structure deformation is calculated in structure solver, it will be transmitted to fluid field again. Iteration goes on in this way and finally converges. Simulation results show the deformation, stress and pressure distribution of flexible wings. All these results are good reference for MAVs design, modification and wind tunnel experiments generally.
Numerical Evaluation on the Cooling Capability of MEMS Based Liquid Metal Cooling Device Used in Harsh Environment
Authors: Deng Zhong-Shan , Liu Jing , Zhou Yi-Xin
Published: June 2009

The thermal management of the increasing fast chips has been a major concern in packaging of micro/nano systems [1]. These chips are squeezing into tighter and tighter spaces with no enough places for heat to dissipate. It is expected that heat flux levels in excess of 100 W/cm2 for commercial electronics and over 1000 W/cm2 for selected military high power electronics will soon become a realistic challenge to overcome. Meanwhile, high-capacity cooling options remain limited for many small-scale applications such as micro-systems, sensors and actuators, and micro/nano electronic components.
Conformal RF Ablation to Reduce “Dead Region” With Adjuvant Injection of Magnetic Micro/Nano Particles: Feasibility Study
Authors: Deng Zhong-Shan , Liu Jing , Zhang Ji-Ren
Published: June 2009

Radiofrequency (RF) ablation is a minimally invasive technique for tumor treatment. Intended benefits of oncological RF ablation include the availability of tumor treatment in nonsurgical candidate, minimal risk to patient, reduced morbidity and shorter recovery period compared with those after conventional surgery, and the potential for treatment on an outpatient basis. RF ablation, by producing heat energy that raises the temperature of the target tissue to a degree sufficient to cause thermally mediated coagulation necrosis, has been shown to be remarkably effective for thermal ablation of small tumors. Although RF hyperthermia has been successful in ablating small tumors, further optimization of the ablation technique is required to induce the larger volumes of coagulation that are necessary to treat larger tumors. In addition, due to the extremely irregular shape of tumor in clinics, the conventional RF ablation technique is hard to produce a conformal lesion to exactly enwrap the tumor as could as possible. This may lead to “dead region” within the area between RF probes and thus a failed treatment. To obtain a conformal treatment of complex tumor, strategies to flexibly control the size and shape of the ablated zone are desired.
An Orthogonal-Beam Tunnel-Effect MEMS Gyroscope
Authors: Liu Jun , Luo Yuanyuan , Li Jingmin , Shi YunBo , Ma Fai
Published: June 2009

Tunnel-effect MEMS gyroscopes have broad applications in astronautics because they have high sensitivity, low measurement ranges, and small volumes. This paper describes the design of a novel orthogonal-beam gyroscope based on the principle of tunnel effect. The mathematical model of this class of gyroscopes is set up and the associated performance is obtained with ANSYS simulation software. Related MEMS technology for the construction of these orthogonal-beam tunnel-effect gyroscopes is also described.
CAD/CAM Integration System of 3D Micro EDM
Authors: Tong Hao , Cui Jing , Li Yong , Wang Yang
Published: June 2009

In 3D scanning micro electro discharge machining (EDM), the CAD/CAM systems being used in mechanical milling of numerical control (NC) are unable to be applied directly due to the particularity of tool electrode wear. Based on industry computer and RT-Linux software platform, a CAD/CAM integration system of 3D micro EDM is developed. In the developed CAD/CAM integration system, the hardware includes mainly a micro feed mechanism for servo control, XY worktable, a high frequency pulse power supply, monitoring circuits etc., and the functions consist of model design, scanning path planning and simulation, NC code generation and post processing, real-time compensating of tool electrode wear, and machining control of states and process. The method of double buffer storage is adopted to transmit numbers of NC machining data. Servo scanning EDM method is used to realize real-time electrode wear compensating and thereby 3D micro structures are machined automatically. The machining experiments are made about model design, parameters optimizing, and process control. The typical 3D micro structures with space curved surfaces and lines have been machined such as micro prism, micro half tube, camber correlation line, and so on. The machining process and results show that the CAD/CAM integration system has the characters of higher real-time, reliability, and general using.
Design and Experiment for High Overloading Piezoceramics Actuator Based on Adaptive Munition
Authors: Shi Yunbo , Wang Haoyu , Liu Jun , Zhang Binzhen , Zhang Wendong
Published: June 2009

Aimed at the problem that the existing piezoceramics actuator can’t withstand high overloading, based on work principle and high overloading environment of adaptive munition, a high overloading piezoceramics actuator was designed. According to the technologic flow manufactured the piezoceramics actuator sample, innovatively designed the elastic metal frame which is used to precompress piezoceramics actuator, ensured that this actuator has better rigidity and performance of anti-pull and anti-overloading, through the technique criteria demarcation and high overloading experiment of packed actuator to confirm that it has better capability of micro-displacement and anti-overloading, it can’t only satisfy the request of high overloading based on adaptive munition, but also apply to the high overloading micro-nano-actuating field of military defence, aviation and spaceflight etc.
Optimization in Design of High-g Accelerometers
Authors: Liu Jun , Qi Xiaojin , Shi Yunbo , Ma Fai
Published: June 2009

Under the operating conditions of high collision and strong vibration, a new high-g piezoresistive accelerometer (with a full range of 150000g) is designed. This design consists of 4-beams and 1-tower. This structure possesses superior anti-shock ability. In optimizing this piezoresistive bridge structure, a tower is etched directly from the back of the mass in KOH by using the (111) plane etch-stop technique. Since the distances between the mass center of the tower and the mass centers of the beams are shortened, anti-shock ability in transverse directions is improved. In addition, the fabrication process is relatively straightforward. Finally, it is found by impact experiments that the linearity of the optimized design lies within 9% for measurements in the range of 0–150000g.
Specimen Size Effect on Fatigue Properties of Surface-Micromachined Al-3%Ti Thin Films
Authors: Park Jun-Hyub , Myung Man Sik , Kim Yun-Jae
Published: June 2009

This paper presents high cycle fatigue properties of an Al-3%Ti thin film, used in a RF (radio-frequency) MEMS switch for a mobile phone and also describes new test method for obtaining static and dynamic characteristics of thin film and reliability evaluation method on MEMS device with thin film developed by authors. Durability should be ensured for such devices under cycling load. Therefore, with the proposed specimen and test procedure, tensile and fatigue tests were performed to obtain mechanical and fatigue properties. The specimen was made with dimensions of 1000μm long, 1.0μm thickness, and 3 kinds of width, 50, 100 and 150μm. High cycle fatigue tests for each width were also performed, from which the fatigue strength coefficient and the fatigue strength exponent were found to be 193MPa and −0.02319 for 50μm, 181MPa and −0.02001 for 100μm, and 164MPa and −0.01322 for 150μm, respectively. We found that the narrower specimen is, the longer fatigue life of Al-3%Ti is and the wider specimen is, the more susceptible to stress level fatigue life of Al-3%Ti was.
Macromodeling Method of Fluid-Structure Interacting MEMS Based on Modal Analysis and Proper Orthogonal Decomposition
Authors: Hao Wentao , Tian Ling , Tong Bingshu
Published: June 2009

Because of their good performance to speed up MEMS system simulation processes, macromodels have aroused lots of attentions of scientists in the last decades. However, studies on FSI (Fluid-Structure Interaction) MEMS devices still can not satisfy the macromodeling requests because of the high complexity of fluid fields. A new method based on modal analysis and POD (Proper Orthogonal Decomposition) is tentatively put forward to reduce the order of FSI MEMS models. The structure macromodeling theory is firstly reviewed. Then the fluid field macromodeling approach is discussed in detail. At last, a 2D fixed-fixed micro-beam is analyzed and the results show that the macromodel extracted in this method can highly decrease the system degrees of freedom, while its precision is still comparable with that of detailed models.