bluuebunny/crossref_metadata_2025 huggingface dataset:
Temperature Measurement in Microfluidic Systems Using Photobleaching of a Fluorescent Slab
Authors: Gui Lin , Ren Carolyn L.
Published: June 2009

Temperature control is key to microfluidic-based Lab-on-a-Chip devices for a variety of applications such as polymerase chain reaction for DNA amplification and isoelectric focusing for protein separation where pH gradients are thermally generated. The most widely used temperature measurement method involves the mixing of the buffer solution with a fluorescent dye, which has a temperature-dependent fluorescent intensity. The temperature distribution in the liquid can be obtained by monitoring the fluorescent intensity distribution in the channel. However, this method can not be easily applied to polymer-made microfluidic chips because of dye absorption and penetration into polymer chips, electrophoresis of dye which causes artificial temperature gradients, and inevitable photobleaching of fluorescent dye. Therefore, a novel method is developed and presented here for temperature measurement by utilizing photobleaching of fluorescent dye. This method includes two novel contributions: i) a specially developed model for converting temperature-dependent photobleaching speed distribution to temperature distribution, and ii) an introduction of a thin polydimethylsiloxane (PDMS) layer with saturated Rhodamine B for solving the above-mentioned dye diffusion and electrophoresis problems. In this new method, a thin PDMS layer saturated with Rhodamine B is bonded with another PDMS layer with microchannels instead of mixing the dye with the buffer solution. Therefore, the problems associated with dye diffusion into PDMS chips and electrophoresis when an electrical field is applied to channels are avoided. The developed theory is validated by comparing the experimentally measured temperature distribution with numerical predicted results. The theory and its validation will be presented and discussed.
Electro-Osmotic Flow With Free Surface in Nanochannels
Authors: Joo Sang W. , Qian Shizhi , Jiang Yingtao , Cheney Marcos A.
Published: June 2009

A thin-film flow induced by the electro-osmosis is studied. In contrast to the single-phase electro-osmosis flow through micro- and nanochannels, the flow considered has a free surface, which may deform with the flow developments. A new type of interfacial instability is identified via a linear stability analysis, and subsequent nonlinear flow behavior, including that for the film surface corrugations, is examined by deriving an evolution equation.
Synthesis of α-Al2O3 Nanopowder From Ammonium Dawsonite
Authors: Ahmadian Namini P. , Babaluo A. A. , Akhfash Ardestani M. , Jannatduost E. , Peyravi M.
Published: June 2009

In this research, α-Al2O3 nanopowder was successfully synthesized via a new wet chemistry (liquid phase reaction) method. Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used for the characterization of the synthesized nanopowder. The FTIR and XRD results showed that α-alumina nanopowder was synthesized from ammonium dowsonite powder after the calcination at 1150 °C for 1 h. Also, SEM micrographs showed that the final nanoparticles have aggregated structures in 50–100 nm range.
Microscale Mass Diffusion Sensing of Polymer Solutions Using Soret Forced Rayleigh Scattering
Authors: Nagasaka Yuji
Published: June 2009

In the casting process of highly functional films, the control of complex micro and nano structures inside the polymer films is one of the most critical factors. The control requires the cross diffusion coefficients in multicomponent solutions because it has a direct influence on the formation of fine structures inside polymer films during the casting process [1]. However, most studies on diffusion in polymer solutions concentrate on measuring diffusion coefficients in binary solutions and only a few measurement techniques of the cross diffusion coefficient can be found. We have developed a measurement technique for the mutual diffusion coefficient in binary solutions, namely Soret forced Rayleigh scattering method [2–4]. In the present paper, we have applied Soret forced Rayleigh scattering method to measure the binary mass diffusion coefficient for the clarification of the cross diffusion phenomena in multicomponent diffusion.
Nanowire-Based High Speed Transparent and Flexible Thin-Film Transistor Devices
Authors: Dattoli Eric N. , Baler Kevin , Lu Wei
Published: June 2009

High-performance transparent and flexible thin film transistors (TFTs) were fabricated on glass and plastic substrates using alligned SnO2 nanowires as the channel material. High densities of crystalline SnO2 nanowires were dry-transferred directly onto the glass/plastic substrates, followed by low-temperature patterning of the source/drain and gate electrodes. Transparent TFTs fabricated on glass substrates show excellent electrical properties and optical transmittance. Excellent mechanical flexibility can be further obtained under cyclic tension experiments in devices fabricated on plastic substrates. The charge carrier mobility was estimated to be as high as 160 cm2/V·s — two orders of magnitude higher than that of conventional amorphous-silicon or organic TFTs. Cutoff frequency > 70 MHz and on/off ratio > 106 have also been demonstrated. The low-cost nanowire growth and dry-transfer processes make this approach a cost-effective means to fabricate transparent and/or flexible TFTs on non-conventional substrates.
A DSMC Study of the Si/Ge Interface Thermal Resistance
Authors: Huang Mei-Jiau , Tsai Dong-Jiun , Liu Liang-Chun
Published: June 2009

In this paper, we present some preliminary simulation results of the thermal resistance associated with a Si/Ge interface. The interface thermal resistance is obtained via a Monte-Carlo (DSMC) simulation tool based on the phonon Boltzmann equation and the single relaxation time approximation. The simulation is made one-dimensional in order to save the computational time by taking advantage of the statistical symmetry in problem. The interface is partially specular and partially diffuse. An inelastic acoustic mismatch model is employed to determine the transmissivity. The interface thermal resistance is consequently computed as a function of the specular reflection fraction. Two different phonon dispersion relations, a sine model and a cubic one, are employed for comparison. Phonon properties are temperature-dependent. Attention will be paid to the difference in the so obtained temperature distributions, particularly near the interface, and the calculated interface thermal resistances. These simulation results are also compared with their finite-difference counterparts with constant phonon properties for the sake of ensuring the validity of the DSMC solver and for the sake of exploring the influence of temperature dependence. Future work will be concentrated on the influence of the layer thicknesses between finitely many interfaces on the interface thermal resistance.
A NEMD Study of the Thermal Conductivity and Surface Roughness of Silicon Thin Films
Authors: Chang Tai-Ming , Weng Chien-Chou , Huang Mei-Jiau
Published: June 2009

The nonequilibrium molecular dynamics (NEMD) approach is adopted in this work to calculate the in-plane lattice thermal conductivity of Silicon thin films. In the simulation, the Stillinger-Weber (SW) potential is employed to capture both two-body and three-body interactions. The periodic boundary conditions are applied in the in-plane directions of a thin film. An additional surface potential is added to atoms that are near the surfaces. This surface potential imposes a force normal to the plane to prevent atoms from evaporation. A constant heat flux is generated by injecting energy into the system somewhere and withdrawing energy somewhere else via the velocity rescaling method. After a sufficiently long simulation time, the time-averaged temperature distribution is calculated and then the thermal conductivity can be obtained by the Fourier’s law. When the average temperature of the system is lower than the Debye temperature (θD = 645 K for Si), quantum corrections to both the MD temperature and the thermal conductivity are carried out. To speed up the computation, the present MD tool is parallelized based on a spatial decomposition technique. In this study, we attempt to investigate the relationship among the model parameters of the surface potential, the surface roughness, and the specular reflection fraction at the boundary that is often used in many theoretical studies.
On Improving the Accuracy of Micromachined Gyroscopes Based on Multi-Sensor Fusion
Authors: Chang Honglong , Zhang Peng , Hu Min , Yuan Weizheng
Published: June 2009

Current state-of-the-art micromachined gyroscopes can not compete with the established sensors in high-accuracy application areas such as guidance and inertial navigation. In this paper one method based on homogeneous multi-sensor fusion was presented to improve the accuracy of the micromachined gyroscopes. In this method several gyroscopes of the same kind were combined into one single effective device through Kalman filtering, the performance of which would surpass that of any individual sensor. The secret of the performance improving lies in the optimal estimation of the random noise sources such as rate random walk and angular random walk for compensating the measurement values. Especially, the cross correlation between the noises of the same type from different gyroscopes was used to establish the system noise covariance matrix and the measurement noise covariance matrix for Kalman filtering to improve the performance further. On the other hand, contrasted with the current static filter design we firstly proposed one difference modeling method to establish the dynamic filter to satisfy the optimal estimation in the situation with angular rate input, in which the mutual subtraction of the measurement values between every two gyroscopes in the sensor array could avoid the trouble of obtaining the true rate. The experiments showed that three gyroscopes with bias drift of 35 degree per hour were able to be combined into one virtual gyroscope with drift of 0.15 degree per hour and 20 degree per hour through the presented static filter and dynamic filter respectively. The multi-sensor fusion method is really capable of improving the accuracy of the micromachined gyroscopes, which provides the possibility of using these low cost MEMS sensors in high-accuracy application areas.
Mechanical-Electrostatic Distortion Analyze and Simulation for MEMS Line Vibration Gyroscope
Authors: Sun Feng , Guo Qiufen , Ge Yuansheng , Ma Longhua
Published: June 2009

MEMS line vibration gyroscope is always drove by electrostatic. When the configuration of the MEMS line vibration gyroscope is symmetry, its mass is vibrated in line at one direction (it is x direction here) and balanced in force at the other direction that vertical to x direction (it is y direction here) in horizontal. But when the configuration of the MEMS line vibration gyroscope is not asymmetry, the electrostatic that putted on the mass at y direction is destroyed. At this condition, one is that the mass is vibrated in line at y direction and produced zero signals; one is that the combs are distorted at y direction because of the destroyed of the balance of the electrostatic at y direction. This paper analyzed the second condition. The model of the distortion was built because the configuration is asymmetry. And it was simulated in Matlab. At the same time, it was analyzed by ANSYS according to the method of the Limited Element. And we got the electrostatic distributing fig and the distortion fig by using ANSYS. Through the compare of two methods, we know that the built model is correct whether or not.
Study on a Positioning and Measuring System With Nanometer Accuracy
Authors: Qi Yong-Yue , Zhao Mei-Rong , Lin Yu-Chi
Published: June 2009

The process of developing a nanopositioning and nanomeasuring system is described. The piezoelectric micro-motion stage is based on the principle of inchworm motion. The traditional single actuator is updated to the double actuators. With the novel principle of push-pull relay movement the stage can move continuously and smoothly. In order to achieve nano-measurement a new method called coupled differential interferometry is proposed. An optical system with 8 times optical path difference is adopted. The new interferometer is simple in concept, without optical paths and easy to set up. In addition the real time error compensation of the interferential signals is accomplished by the Heydemann model. The experiment results show: the minimum step of the micro-motion stage is 18nm, the accuracy of the interferometry is 10–12nm.
Near-Field Radiation Interaction With Molecules in Optical Microcavity
Authors: Guo Zhixiong , Quan Haiyong
Published: June 2009

Evanescent radiation-molecule interactions in an optical microcavity device are characterized. The device is operated at whispering-gallery modes, and consists of a microcavity and a micro-waveguide coupled by a sub-micrometer air-gap. Under optical resonance, a strong evanescent field arises along the periphery of the circular resonating microcavity. This radiation will certainly interact with molecules inside the field and may induce changes in the resonant field. Such induced changes are investigated and its potential in the detection of single molecules is discussed.
Ink-Jet as a MEMS Manufacturing Tool
Authors: Wallace David , Hayes Donald , Chen Ting , Shah Virang , Radulescu Delia , Cooley Patrick , Wachtler Kurt , Nallani Arunkumar
Published: June 2009

In the last decade, ink-jet has come to be viewed as a precision microdispensing tool, in addition to its huge success in color printing. Today, this tool is being used in a wide range of applications, including electrical & optical interconnects, sensors, medical diagnostics, drug delivery, MEMS packaging, and nanostructure materials deposition. Ink-jet microdispensing is data-driven, non-contact, and is capable of precise deposition of picoliter volumes at high rates, even onto non-planar surfaces. Being data-driven, ink-jet dispensing is highly flexible and can be readily automated into manufacturing lines. This paper will illustrate a few of the applications of ink-jet technology that are either MEMS manufacturing applications, or relevant to potential MEMS manufacturing applications.
Electrospinning of Oriented Polymer Nanofiber Bundle
Authors: Wu Dezhi , Sun Daoheng , Wang Lingyun
Published: June 2009

Electrospinning was firstly employed in this paper to prepare oriented polyethylene oxide (PEO) nanofibers and bundles, in which two pieces of triangle-shaped electrically conductive substrates whose tips are opposite to each other are introduced as Oriented Collection Electrodes (OCEs) so as to change electric field in the conventional electrospinning. When the auxiliary voltages of 0V, 50V, 100V and 150V were applied to the OCEs, the experiment results show that the charged nanofibers near the tips were stretched and collected to be a bundle which bridges the two tips, and the nanofibers deposited along the edge of collection electrodes were parallel and perpendicular to the edge of collection electrodes because of electrostatic interactions.
The Role of Thermal Excitation of D Band Electrons in Ultrafast Laser Interaction With Noble (Cu) and Transition (Pt) Metals
Authors: Lin Zhibin , Zhigilei Leonid V.
Published: June 2009

The temperature dependences of the electron heat capacity and electron-phonon coupling factor for noble (Cu) and transition (Pt) metals are investigated based on the electron density of states (DOS) obtained from ab initio electronic structure calculations. For Cu, d band electrons could be thermally excited when the electron temperature exceeds ∼3000 K, leading to a significant increase, up to an order of magnitude, in the electron-phonon coupling factor and strong enhancement of the electron heat capacity away from the linear dependence on the electron temperature, which is commonly used in most of the current computational and theoretical investigations of ultrafast laser interactions with metals. Opposite to the case in Cu, the thermal excitation of d band electrons in Pt leads to a monotonic decrease of the electron-phonon coupling factor and contributes to significant negative deviations of the electron heat capacity from the linear dependence in the range of electron temperatures that are typically realized in ultrafast laser material processing applications. Strong and drastically different temperature dependences of the thermophysical properties predicted for Cu and Pt point to the importance of the electron DOS effects and the necessity of full consideration of thermal excitation of d band electrons for realistic modeling of short pulse laser interaction with noble and transition metals.
A 2.4-GHz 0.18μm Full-CMOS Single-Stage Class-E Power Amplifier With Temperature Effect for ISM Band Wireless Communication
Authors: Wang Mu-Chun , Hsieh Zhen-Ying , Hsu Chieu-Ying , Chen Shuang-Yuan , Huang Heng-Sheng
Published: June 2009

In this paper, we present a single-stage class-E power amplifier with multiple-gated shape as well as 0.18μm complementary metal-oxide-semiconductor (CMOS) process for 2.4GHz Industry-Science-Medicine (ISM) band. This power amplifier is able to be easily integrated into the system-on-chip (SoC) circuit. For the competition of lower cost and high integration in marketing concern, CMOS technology is fundamentally better than GaAs technology. We adopt the Advanced Design System software in circuit simulation coming from Agilent Company through the Chip Implementation Center (CIC) channel plus TSMC 0.18 μm device models. The simulation results with temperature effect, show the good performance such as an output power achievement of +22dBm under a 1.8V supply voltage; the power-added efficiency (PAE) is over 30%; the output impedance (S22) and the input impedance (S11) are fully lower than −15dB; the power gain (S21) is +11dB; the inverse isolation (S12) is below −26dB. This amplifier reaches its 1-dB compression point at an output level of 16.5dBm related to the input power 6.5dBm position. The output power with temperature variation from 0°C to 125°C depicts an acceptable spec. range, too.
Fundamental Research on Micro Electroforming of Metal Microstructures by Using Shielded Anode
Authors: Zeng Yong-Bin , Zhu Di , Qu Ning-Song , Hu Yang-Yang
Published: June 2009

Metal microstructures with high-aspect-ratio and complex features have become a real challenge for the microfabrication field. A novel metal micro-parts fabrication technology is presented in this paper. The anode which also serves as a mask is patterned by UV lithography, and used to confine the region of electrodeposition. With the increasing of the thickness of electrodeposition, the mask is detached from the substrate periodically. 3-Dimensional microstructures with limitless aspect ratio can be fabricated by this technology in principle. Immersion tests show that pyrophosphate bath is more appropriate for this technology than acid sulfate bath. Cell voltage is employed to monitor the electro forming process for it provides some process information such as flash deposition, shorting occurrence, et al. Two types of movement between the mask and the cathode have been carried out on the self-developed equipment to demonstrate its feasibility. Micro bars with vertical sidewall and micro structures with slanting profile have been produced.
Fluid Flow and Heat Transfer Characteristics of Slug Bubbly Flow in Micro Condensers
Authors: Hu J. S. , Chao Christopher Y. H.
Published: June 2009

Experiments were carried out to study the condensation flow pattern in silicon micro condenser using water as medium. Five flow patterns were identified under our experimental conditions. Slug-bubbly flow and droplet/liquid slug flow were found to be the two dominant flows in the micro condenser. These two flow patterns subsequently determined the heat transfer and pressure drop properties of the fluid. It was observed that only slug-bubbly flow existed in low steam mass flow and high heat flux conditions. When the steam mass flow rate increased or the heat flux dropped, mixed flow pattern occurred. An empirical correlation was obtained to predict when the transition of the flow pattern from slug-bubbly flow to mixed flow could appear. In the slug-bubbly flow regime, heat transfer coefficient and pressure drop in the micro condensers were studied. It was found that micro condensers with smaller channels could exhibit higher heat transfer coefficient and pressure drop. At constant heat flux, increasing the steam mass flow rate resulted in a higher heat transfer coefficient and also the pressure drop.
Fabrication of Nanoscale Linewidth Standards Based on Multilayer Thin Film Deposition Technique
Authors: Zhao Fengxia , Jing Weixuan , Jiang Zhuangde , Duan Haoliang
Published: June 2009

To overcome the difficulties in the fabrication of nanoscale linewidth standards with lithography, a method of fabricating nanoscale multiple linewidth standards based on multilayer thin film deposition technique is presented in this paper. This method can be implemented easily and does not require the use of complex and expensive techniques, and it has advantage of well-controlled linewidth over various millimetres (using thin film thickness control) and versatile materials selection of the grating lines. Nanoscale multiple linewidth samples with nominal linewidths of 20 nm, 25 nm, 35 nm have been fabricated with the presented method. The lines of the fabricated samples have uniform attributes and good linearity over hundreds microns.
Performance Simulations of Tesla Microfluidic Valves
Authors: Zhang S. , Winoto S. H. , Low H. T.
Published: June 2009

A three-dimensional (3-D) parametric model of Tesla-type valves is proposed. A geometrical relationship is derived for optimization study, and based on the model, performance investigations in terms of diodicity and pressure-flow rate characteristics of the valve are numerically carried out with same hydraulic diameter and different aspect ratios (of the model cross-sectional dimensions) ranging from 0.5 to 4. The 3-D computational simulations show that, for the same hydraulic diameter, the unity aspect ratio gives higher diodicity at Reynolds number less than 500 and higher will be achieved with bigger aspect ratio when the Reynolds number is above 500. Investigations of pressure-flow rate characteristics of the Tesla valve show that Tesla valve with high aspect ratio gives more flow control ability.
Penetrating Process Analysis of AFM Diamond Tip
Authors: Hu Z. J. , Yan Y. D. , Zhang Y. H. , Sun T. , Dong S.
Published: June 2009

A mechanical micro-scratching system based on Atomic Force Microscope (AFM) and three-dimensional high precision stage was built up. In the machining process with diamond tip, the process of depth controlling was determined by the relation between the loading movement of the stage and the tip penetration depth. By theoretical analysis of loading process with diamond tip, a mathematical model correlated loading movement and the penetration depth was founded, and the loading efficiency formula of elastic tip was also acquired. Verified by experiments, such equations reflected the indenting process of the system and provided theoretical basis on optimizing the penetration depth control arithmetic.
Experimental Study on Fullerene Formation Process in Toluene Flame at Low Pressure Condition
Authors: Shibahara Masahiko , Shimizu Tsubasa , Kunioshi Nilson , Takada Hiroshi
Published: June 2009

Polycyclic Aromatic Hydrocarbons generated in the combustion processes of fuel rich hydrocarbon flames are considered to be important precursors of soot that causes environmental pollution. On the other hand, in a combustion process under low pressure conditions, the generation of fullerenes which are one of large cage-shaped carbon clusters was reported. Combustion synthesis of fullerenes is expected to be one of the mass production methods of fullerenes and a premixed flame of toluene and oxygen is utilized in real mass production process of fullerenes. However, the fullerene formation mechanism from PAH in toluene and oxygen premixed flames has not been clarified yet. Therefore, in the present study, contents of PAH and fullerene in the total soot obtained from premixed flames of toluene and oxygen surrounded with premixed flame of methane and oxygen under various physical conditions were analyzed through gas and liquid chromatography. In the present study over 5 weight percent PAHs were found in the collected soot samples and 22 kinds of substances in PAHs can be specified by using the standard sample and 10 isometric structures of PAHs can be specified by using a gas chromatograph system. When the flame fluctuation was small because of low flow rate of the center and outer flames, the fullerene content in the soot sample increased and the PAH contents of lower molecular weight increased with the increase of the pressure in the chamber. When the flame fluctuation was relatively large because of high flow rate of the center and outer flames, the fullerene content in the soot sample had the maximum peak and the PAH contents of lower molecular weight were dramatically changed from those in the case with small flame fluctuation. Contents of C60 in the total fullerenes increased and those of C70 decreased with the increase of the pressure in the chamber.
Micro-EDM Milling of Micro Compressor Prototype
Authors: Wang Zhenlong , Dong Yinghuai
Published: June 2009

Micro power system is becoming more and more important for micro- and nano-scale system. The fast development of MEMS (Micro Electromechanical Systems) has strongly enhanced the application of new harder work materials. The fabrication of metallic 3D microstructures has been one of the most attractive topics of micro machining. Currently the basic materials of Micro-turbine Engineering were nonmetal materials such as SiC, most of them are 2D or quasi-3D structures. This paper focuses on the manufacturing process on micro compressor prototype by micro-EDM milling. The micro compressor prototype contains the rotor disk and stator disk. A simple tool path generation by CAD/CAM software and a general electrode wear compensation strategy is presented. The micro compressor prototype with rotor and stator disks was successfully fabricated by using this strategy, and the materials of workpieces are nickel alloy GH4169 and titanium alloy TC4.
Electrochemical Machining of Micro-Structures With Nanosecond Pulses
Authors: Zhang Zhaoyang , Zhu Di , Qu Ningsong , Wang Kun
Published: June 2009

Electrochemical machining (ECM) is considered an advanced and promising technique due to several special advantages, such as non-contact machining without cutting force, no tool wear and heat-affected layer, etc. Base on the experimental results of micro-ECM, the influence of predominant process parameters, i.e. electrolyte concentration, pulse duration, period and voltage amplitude of power supply, on machining accuracy were investigated and discussed. Experimental showed that lower voltage amplitude and shorter pulse duration in micro-ECM process could produce more accurate micro structure shape. Using the self-developed experimental system, the micro tool-electrode and the complex micro-structures were sequentially machined. Upon the application of ultrashort voltage pulses, the letters with 20μm in line width were fabricated stably by the W tool electrode with 10μm diameter.
The Simple Fabrication and Packaging of Micro DMFC by MEMS Technology
Authors: Yao Da-Jeng , Lai Yu-Chia
Published: June 2009

This paper reports a simple and cheap fabrication for a micro direct methanol fuel cell, featured by MEMS technology. KOH solution was used to fabricate the microchannel. Then laser technology was used to drill fuel feeding hole and connections between formed microchannels. Finally, Ti/Cu/Pt layers of 100Å/3000Å/800Å in thickness were coated onto the surface of etched microchannel by e-gun evaporator as the catalyst layer to increase the area of electrode. Two different widths of microchannels, which are 200μm and 400μm, were fabricated. The advantage of the designed package was self-aligned with the chips by using glass chips. The aligned holes on both fabricated chip and glass chip were drilled by laser, which could be self-aligned and locked by screw. Therefore it’s easy to assemble the chip, MEA, and glass chip by this simple package way. The designed package could be used to prevent the fuel leakage and chip damage problems under operation. The performance of this μDMFC was measured up to 40mW/cm2 at 60°C with 2M methanol solution.
Numerical Simulation of Self-Induced Thermocapillary Flow for Non-Uniform Evaporating Meniscus in Capillary Tubes
Authors: Li You-Rong , Lan Bo , Peng Lan , Liu Ying-Jie
Published: June 2009

A computational model was developed to describe self-induced thermocapillary convection for non-uniform evaporating meniscus in vertical capillary tubes, which was filled with ethanol, methanol or water. The diameters of capillary tubes ranged from 100 μm to 1000 μm. The direct numerical simulation using control volume approximation was used to investigate the thermocapillary flow in the liquid phase. Three types of distribution of the heat flux along the liquid-vapor meniscus interface were investigated for various Marangoni numbers, to characterize the flow pattern under conditions close to realistic operating parameters. The simulation shows that the flow pattern depends on the thermal boundary condition on the liquid-vapor meniscus interface and the Marangoni number, but is very insensitive to the buoyancy force for thermocapillary convection for non-uniform evaporating meniscus in the capillary tube with the radius ro<500μm.
Motion of Electron Gas and the Induced Nanofilm Electromigration
Authors: Cao Bing-Yang , Zhang Qing-Guang , Guo Zeng-Yuan
Published: June 2009

Understanding how electron gas moves and induces electromigration is highly desirable in micro- and nano-electronic devices. Based on introducing some novel concepts of electron gas momentum, kinetic energy and resisting force, we establish the continuum, momentum and energy conservation equations of the electron gas in this paper. Through analyzing the control equations, the Ohm’s law can be derived if the inertial force or the kinetic energy of the electron gas is ignored. Thus, the Ohm’s law is no longer applicable if the variation of the electron gas momentum is too large to be ignored. For instance, the kinetic energy variation can not be ignored for the electron gas with a high velocity flowing along the conductor with variable cross-sections. Under such conditions, the electric resistance of the section-variable conductors is a function of the electric current density and direction, which is referred to as a kinetic energy effect on the electric resistance. Based on the control equations of the electron gas motion, the electron wind force and the kinetic energy can also be calculated. The kinetic energy transferred from the electron wind to metallic atoms increases greatly with the increasing electric current density. It may be comparable with the activated energy of the metallic atoms in nanofilms. Thus, the electromigration induced by the electron wind can be regarded as another kind of kinetic energy effect of the electron gas, i.e. kinetic energy effect on the electromigration.
Design of Decouple on MEMS Tunneling Gyroscope
Authors: Li Wenwang
Published: June 2009

The proposed microelectromechanical (MEMS) tunneling gyroscope uses a general principle of operation that is commonly used for scanning tunneling microscopy (STM). In STM a bias voltage is applied between a sharp metal tip and a conducting sample. When the tip and sample are brought to within a few Angstroms (Å) of each other, a tunneling current can flow due to quantum mechanical tunneling effects. Because the tunneling current is exponentially dependent on the separation between the tip and the sample, the distance between the tip the sample can be measured to within 10−3 (Å). There are two motions in two directions in tunneling gyroscope: drive mode and sense mode. For decoupling drive mode and sense mode, two schemes are studied forward: (1) doubly decoupled comb drive plate oscillation gyroscope: There is only longitudinal relative motion, no landscape orientation relative motion between two electrodes.(2) Cantilever tunnel gyroscope: By using of ladders cantilever, relative motion of the silicon tip in the drive direction was reducing.
Design of Pulsed Jet On-Off Valve Based on Giant Magnetostrictive Actuator
Authors: Meng Aihua
Published: June 2009

The pulsed jet device is a kind of device that can jet rapidly with micro flux. Present jet methods cannot fulfill the requirements of a large-flux, high-speed and stability in some applications. Combining with the character of pulsed jet device and the advantage of high-speed on-off valve, a new kind of micro-flux jet device —pulse jet on-off valve was designed. The basic structure and the working theory of the device were introduced first; then the valve was studied in detail on the basis of the requirements of jet speed and flux, including structure selection, rated pressure computation, dimension designing etc.. The advantages and disadvantages of actuators driven by electromagnetic, piezoelectric and giant magnetostrictive material (GMM) were compared, then GMM was chosen to drive the pulsed jet on-off valve. The flux and jet speed response experiments demonstrated that the pulsed jet on-off valve based on giant magnetostrictive actuator (GMA) could fulfill the requirements of application.
Topology Optimization of MEMS-Based Biodegradable Controlled Drug Delivery System for Combination Therapy
Authors: Yu Ruixia , Chen Hualing , Chen Tianning , Wang Hairong
Published: June 2009

MEMS-based biodegradable controlled release system with micro multi-chambers can respectively enclose two drugs in different chambers to realize a combination therapy. In order to synchronously obtain the linear release of two drugs, it is necessary to completely investigate the topology optimization of the system. This paper introduces the theory of multi-objective topology optimization into MEMS-based biodegradable controlled release system for the combination therapy. Furthermore, a new method of CA-based evolutionary structural optimization (CA-ESO) is presented to accomplish the topology optimization of this controlled release system. The result shows that the optimized drug delivery system can achieve the objective of the synchronizing linear release for two drugs. The conclusion illustrates that the CA-ESO method proposed in this paper is validity for the topology optimization of MEMS-based biodegradable controlled release system.
Micro/Nano Piezoelectric Composites for Advanced M/NEMS
Authors: Jiang Xiaoning , Yuan Jian R. , Cheng An , Snook Kevin , Hackenberger Wesley
Published: June 2009

In this paper piezoelectric composites are presented for advanced micro and nano electromechanical devices. The properties of piezoelectric composites (1-3 and 2-2 connectivity) were analyzed and a micromachining process for bulk piezo materials deep etching was developed for piezoelectric composites fabrication. As an example, micromachined piezoelectric composites with center frequency of 20–50 MHz were prototyped. The micro-piezoelectric composites were characterized showing unprecedented properties for high frequency ultrasound imaging and M/NEMS applications.
Fluid Magnetic Abrasives Based on Micron-Sized Carbonyl-Iron Particles and Its Applications in the Precision Finishing Process
Authors: Sun Huanwu , Yang Shichun
Published: June 2009

The fluid magnetic abrasive (FMA) is a new type of precision finishing abrasives, which is typically prepared by dispersing the magnetic particles, nonmagnetic abrasives, surfactants in a non-magnetizable carrier liquid. As the functional particles, the characteristics of magnetic particles have a great impact on the properties of FMA. In our experiment, the micron-sized carbonyl-iron (CI) particles (typical size: 3 μm–5 μm) are found to be ideally suited for the preparation of FMA. In this paper, the selections of micron-sized carbonyl-iron particles suitable for the FMA, the preparation techniques, the finishing mechanism and finishing process are presented. Some key parameters of FMA that may affect the finishing efficiency and the final surface roughness are analyzed theoretically. The experimental results are discussed as well in this paper.
Cell-Based Drug-Screening Method Using Total Internal Reflection Microscopy
Authors: Lee Yongku , Koo Sangmo , Yoo Jung Yul
Published: June 2009

We propose a cell-based method, which analyzes the adhesion of living cell and its substratum, as an alternative to animal experiment with regard to pharmacy industry. This is because cell viability has been well adopted to determine whether the environment of the cell is proper for its growth and development, which can be quantified by measuring the cell-to-substratum adhesion. However, conventionally measuring the adhesion is known as a very troublesome and time-consuming task which involves several times of manually washing-and-counting process. Therefore, in the proposed method, for the purpose of analyzing the cell-adhesion more conveniently and quantitatively, we adopted a total internal reflection microscopy (TIRFM) which can illuminate the cell contact within the adhesion region specifically and detect its fluorescence not being interrupted by other fluorescence from the cell body far from the substrate. Thus, we obtained time-series TIRFM images which showed that cell contacts were developing or decaying under various conditions; normal to toxic environment, which can represent various density conditions of drug candidate in screening for determining the most appropriate drug composition. Moreover, the present method can be used for commercializing cell-based microchip in drug screening industry — the money cow.
A New Structure of Cantilever-Based Infrared Focal-Plane Array
Authors: Wang Xin , Yu Xiaomei , Li Ting , Liu Ming , Liu Xiaohua , Zhao Yuejin
Published: June 2009

This paper presents the design, fabrication and analysis of an infrared focal-plane array (FPA) consisting of bi-material cantilevers. The bi-material cantilevers are made of silicon nitride (SiNx) and aluminum (Al), and which will bend as the temperature changes due to the difference of the two materials in thermal expansion coefficients. In order to enhance the infrared (IR) absorption efficiency of the FPA, deep reactive ion etching (DRIE) technique was introduced to remove the backside Si of the structures. Therefore the IR light can reach the FPA directly. The thermomechanical sensitivity for the finished FPA is measured to be 0.134 μm/K by profile meter, and the noise-equivalent temperature difference (NETD) of the system was estimated to be 18mK.
Adhesive Force in Micro- and Nano-System
Authors: Zhu Ying-Min , Jia Jian-Yuan , Fan Kang-Qi , Huang Chun-Yue
Published: June 2009

One of the most important reliability problems in micro- and nano-systems is stiction, the adhesion between micro-devices due to surface forces. Although several different physical theories had been put forward to investigate the adhesion problems in micro- and nano-systems, none of them can give a continuous variation of the adhesive force with the distance (if the micro-devices contact, the distance is the negative compressive deformation) between micro-devices. After reviewing the known physical theories, three combined adhesive models are developed to provide a continuous variation of the adhesive force with the distance. This is done by rectifying the coefficients and definition domains of the adhesive theories available based on the maximal stretch deformation of elastic bodies given by them after a parameter of critical contact distance is introduced to the current adhesive theories. A comparison between a widely used numerical method and the combined adhesive models shows that the combined adhesive models established in this article are valid in investigating the adhesive force in micro- and nano-systems.
Functionalization of Microcantilever Sensors Using Inkjet Drop-on-Demand
Authors: Post Nicholas J. , Chiu George T.-C.
Published: June 2009

Chemical and biochemical sensors based on microcantilever arrays have emerged as new platforms for sensitive analyte detection. A critical step in the manufacture of microcantilever sensors is the functionalization process, where a chemically selective layer is deposited onto the surface of the cantilever. Inkjet drop-on-demand has been recognized as a befitting technology for depositing these layers because of the ability to repeatedly deposit precise amounts of fluid. This paper presents experimental results of applying inkjet printing to functionalize microcantilever sensors. Methods for tuning inkjet drive pulse are presented along with characterization of drop displacement. Strategies for printing the functional layer are presented and system capabilities are demonstrated by depositing black ink onto cantilevers.
Characterization of Surface Layer of Silicon Wafer by Using Nano Indenter
Authors: Sun Yu-Li , Zuo Dun-Wen , Zhu Yong-Wei , Xu Feng , Wang Min
Published: June 2009

Mechanical properties of the silicon wafer are evaluated by a nano indenter system with the continuous stiffness measurement (CSM) technique. Contact stiffness, hardness and elastic modulus of the silicon wafer are continuously measured during the loading in an indentation test. The results show that when the contact depth is between 20 and 32 nm, its contact stiffness is linear with the contact depth, and its hardness and elastic modulus keep constant at 10.2 GPa and 140.3 GPa respectively, which belong to the oxide coating of the silicon wafer. When the contact depth is between 32 and 60 nm, its contact stiffness is not linear with the contact depth, and the hardness and elastic modulus increase rapidly with the contact depth, because they are affected by the bulk material. When the contact depth is over 60 nm, the contact stiffness of the silicon wafer is linear with the contact depth again, and the hardness and elastic modulus keep constant at 12.5 GPa and 165.6 GPa respectively, which belong to the silicon wafer, the bulk material.
Bubble Based Micro/Nano Fabrication Method
Authors: Bai Xiao-Dan , Liu Jing
Published: June 2009

Micro/nano structures, especially those in one dimensional, such as nano wires, are commonly used building blocks for the bottom-up assembly of electronic, photonic or mechanical devices. However, their fabrications are generally limited to the expensive equipments and methods capable of only working in an extremely small space. A big challenge facing the current scientific society is to overcome this barrier and build up a bridge between the macroscopic manipulation/observation and the fabrication in small world. Here, we proposed a new conceptual fabrication method, which can easily be implemented to synthesize, etch and construct micro or nano structures through manipulating the large scale bubbles composed of specific chemical compounds. The core of the method lies in the chemical reaction occurring at the interfaces between two or more soap bubbles. A surprisingly unique virtue of the bubble is that it can have a rather large diameter however an extremely small membrane thickness, whose smallest size even reaches nano scale. Therefore, the chemical reaction and synthesis occurred in the common boundary of such contacting bubbles would lead to products with very small size. Most important of all, all these were achieved via a much easy and straightforward way. To better understand the physical picture of the new method, the principle and mechanism for the bubble based fabrication process were interpreted. Several fundamental equations for characterizing the bubbles were proposed and preliminarily discussed. As the first trial to demonstrate the new concept, several typical micro structures were successfully fabricated in our lab. Particularly, a micro wire which can be used as tiny temperature sensor was made and tested. Being flexible, easily controllable and observable, environmentally friend and extremely low in cost, the present method is expected to be a significant technical route for making micro/nano structures in the near future. It also indicated for the first time that blowing soap bubbles means not just funny but also opens a new world for micro/nano fabrication.
Incorporate Research on Scratching and Uniaxial Tension of Three-Dimensional Microconstruction Simulation Based on Molecular Dynamic
Authors: Liang Yingchun , Chen Jiaxuan , Bai Qingshun , Tang Yulan , Chen Mingjun
Published: June 2009

A method of incorporating research is proposed on scratching and uniaxial tension based on molecular dynamics (MD) with embodied atom method (EAM) for single copper in this paper. The process of tri-pyramid diamond tool scratching the single copper on the (010) plane is simulated under different penetrated depths. The details of scratching process and uniaxial tension are depicted in atomic view. The phenomena of heal-up surface, dislocations and burr are shown after the workpiece is scratched and the principle of that is attempted to analyze. The defects of the surface and subsurface of the workpiece scratched are represented and analyzed by the perspective of dislocations and radial distribution function (RDF). Whereafter the uniaxial tensile simulation of the “real” workpiece after scratching is performed. The mechanism of deformation and the details of change under the uniaxial load are analysed through the stress-strain curve that is combined with the perspective of atom. From simulations results, it is found that the dislocations only occur on the surface and subsurface of workpiece at the small scratching depth, while the dislocations are nucleated and emitted in front of tool and beneath the tool under the deep scratching depth. Dislocations disappear when they propagate to the surface. After the tool escapes the workpiece, the atoms on surface of the workpiece scratched heal up to some extent by the inter force of atoms, while some of the pile-up atoms on surface of tool are attracted backwards surface of workpiece, then form the burr, and others of those atoms are absorbed on the tool’s surface. The number of defects from surface and inner of workpiece increase when the scratching depth is doubled. The order of crystal decreases, especially long range order. It is shown that the penetration depth into the workpiece during scratching affects both surface pile-up and residual defect generation that is important in assessing the change of material properties after being scratched. In the process of the simulation of uniaxial load, the yield stress decrease with the increasing depth of cutting, and dislocations are nucleated at the bottom of groove, especially at the position where the tool escaped nearby burr firstly, and dislocations at ∼45° are observed. It shows that groove is the source of the dislocations aroused. The break-up point is near to the middle of workpiece with increasing depth with groove.