bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurement of Solvent Vapor Absorption by Polydimethylsiloxane Using Quartz Crystal Microbalance
Authors: Leung W. W. F. , Chao C. , Cheng C. H. , Lei K. F. , Ngan D. , Lau C. K. , Tse W. C.
Published: June 2009

A new micro-electromechanical system (MEMS) gas sensor has been developed using quartz crystal microbalance (QCM) with adsorbent coated in form of nanofibers on the QCM sensor. The nanofibers with fiber diameter typically around 200–300 nm increases the specific surface area to enhance adsorption. The QCM is made to oscillate at its natural resonance frequency. Upon exposure of the gas sensor to a given gas, the adsorbed gas onto the nanofibers adds a small mass which changes the natural frequency of the oscillation. By detecting the frequency shift due to adsorption of a given gas, the presence of the gas is detected, and by measuring the frequency shift, the amount of gas being adsorbed at a given pressure and temperature is quantified via the Sauerbrey equation [1]. A circuit has been developed to read the frequency shift due to the energy dissipation in the QCM coated with Polydimethylsiloxane (PDMS) nanofibers under the environment of several solvent vapors. The developed circuit includes two crystal oscillator circuits, two QCM’s which are respectively 1MHz reference QCM and a coated QCM, RC filter and AND gates. The results of the frequency shift between the reference QCM and the coated QCM were recorded on the oscilloscope so as to investigate the relationships between the frequency shift and the amount of vapor adsorbed for different gases. Ultimately, Volatile Organic Compounds (VOCs) are the target to be monitored and a MEMS based sensor will be developed similar to the present QCM gas sensor discussed herein. This work provides the feasibility study for using nanofiber coating to enhance the adsorbent specific area and a stand-alone QCM sensor for making measurement.
Measurement of Intracellular Drug Concentration in a Single Cancer Cell Isolated in a Microfabricated Biochip for Cancer Diagnosis
Authors: Li Paul , Chew Derek
Published: June 2009

A microfluidic biochip has been fabricated to retain a single cell (e.g. a cancerous cell) within a U-shaped cell retention structure for real-time monitoring of cellular changes over long periods of time (hours). Experiments illustrate the cell heterogeneity in drug responses, and demonstrate the significance of the microchip platform for cancer diagnosis. This microdevice provides a clinical diagnostic platform to evaluate multi-drug-resistance in cancer patients. This device may increase the effectiveness of current chemotherapeutic strategies by evaluating an individual’s cellular response to these agents.
Manipulation of Individual Beads Using Submicron Magnetic Features in Microfluidic Channels
Authors: Peng Zhengchun , Hesketh Peter , Joseph Paul
Published: June 2009

We developed a method to manipulate submicron paramagnetic beads in such a way that we not only collectively confine the beads to a specific location inside a microfluidic channel, but also control the positions of the individual beads. The manipulation was based on the attraction force between moving paramagnetic beads and stationary ferromagnetic (e.g., NiFe) features subjected to an external uniform magnetic field. The position of trapped beads was investigated by both theoretical prediction and experimental validation. The control of individual beads in large number allowed us to adjust the number density of beads on a surface as well as optimize the design of the detection elements for the beads.
Dynamics Evolution of Shock Waves in Laser-Material Interaction
Authors: Gacek Sobieslaw , Wang Xinwei
Published: June 2009

In this work, the dynamics of the shock wave in laser-ablated argon plume with its evolution through the background gas is explored at the atomic level. Molecular Dynamics (MD) simulations have been conducted which give the insight into atomistic scale interaction and correlation effects of the propagating shock wave in the background medium. The supersonic shock wave front carries inherent sharp increase in density, temperature, and pressure. These thermodynamic parameters of the expanding shock wave are evaluated with emphasis on the kinetics of the shock wave front. The position of the shock wave front has been defined and determined over nanoseconds. Extensive research is elaborated upon to study the inside structural evolution of the shock wave and the effect of optical absorption depth.
Numerical Analysis of Dry Gas Face Seals With Spiral Groove and Inner Annular Groove
Authors: Peng Xu-Dong , Tan Li-Li , Li Ji-Yun , Sheng Song-En , Bai Shao-Xian
Published: June 2009

A two-dimensional Reynolds equation was established for isothermal compressible gas between the two faces of a dry gas face seal with both spiral grooves and an inner annular groove onto the hard face. The opening force, the leakage rate, the axial film stiffness and the film stiffness to leakage ratio were calculated by finite element method. The comparisons with the sealing performances of a typical gas face seal only with spiral grooves onto its hard face were made. The effects of the face geometric parameters on the static behavior of such a seal were analyzed. The optimization principle for geometric parameters of a dry gas face seals with spiral grooves and an inner annular groove was presented. The recommended geometric parameters of spiral grooves and circular groove presented by optimization can ensure larger axial stiffness while lower leakage rates.
Study on Deformation of a Laser Surface Textured Mechanical Seal
Authors: Peng Xu-Dong , Sheng Song-En , Li Ji-Yun , Cai Yong-Ning , Bai Shao-Xian
Published: June 2009

Laser surface texturing (LST) provides a unique method for applying custom textures to metals, ceramics, and polymers. Etsion has presented a new type of mechanical seal by applying laser surface texturing onto the faces. According to Etsion, such a textured face seal (LST-MS) helps to reduce face friction and wear and can be used at higher sealed fluid pressures than that of a plain face seal. Such a new seal may be subjected to face deformation, and study on the effect of face deformation on sealing behavior of a LST-MS is important. In this paper, a finite element analysis was used to solve the Reynolds equation for liquid film pressure between the faces of a LST-MS. The deformation of two faces caused by sealed medium pressures and liquid film pressure was calculated for a LST-MS consisting of a stator ring with different constructions and/or constrictions. The effects of face deformation on sealing performances, such as leakage rate, film axial stiffness and the ratio of film stiffness to leakage of such a seal were studied. The stability of several seals with different constructions and constrictions was examined. It was suggested that selecting suitable constructions and/or constrictions will improve the stability of such a LST-MS.
On the Ultrasonic Manipulation of Micro/Nano Particles
Authors: Yang Hui , Guo Hang
Published: June 2009

In this paper, we study the ultrasonic manipulation of micro/nano in an ultrasonic standing wave field. Starting from the forces acting on particles in stationary standing wave field, we studied the factors affecting ultrasonic manipulation of micro/nano particles within the fluidic medium. Based on analyzing particles’ motion in an ultrasound – gravity coupled field, we proposed and discussed a new application using ultrasonic manipulation of particles to categorize different kinds of micro/nano particles in fluidic medium.
Study of Package Technologies for Implantable Microdevices
Authors: Li Weihong , Shi Zhenjiang , Guo Hang , Chen Shiqing , Li Xiuhan , Zhang Haixia
Published: June 2009

This paper presents a study of packaging technologies for implantable microdevices. A RF microcoil is first designed and fabricated for implantable microdevices. Then, two methods using different materials and technologies for packaging have been developed. A RLC resonance circuit is adopted to test packaging performance. Measured results accord well with the predicted results from the circuit model and show that the method using multilayer SixNy-SiO2-SixNy dielectric thin films and silicone have better packaging performance to let the implanted microdevice be able to work chronically.
Design and Fabrication of a Micro-Knife for Minimally Invasive Surgery
Authors: Guo Hang , Yang Hui , Zou Liming
Published: June 2009

In this paper, a micro-knife for minimally invasive surgery is proposed. It is a silicon horn shape and works in an ultrasonic longitudinal vibration mode to realize the precise incision with its sharp tip at one end. Finite element method in ANSYS is used to analyze and design the device to obtain the vibration frequency and displacement amplitude of the longitudinal mode. In the end, microfabrication of the proposed micro-knife is presented.
Failure Investigation and Analysis of Abnormal Capacitance of Accelerometer After ICP Release
Authors: An Ping , He Yandong , Wang Shitao , Bai Yanping , Hao Yilong
Published: June 2009

An abnormal capacitance case of capacitive accelerometer after inductive coupled plasma (ICP) release was investigated to solve the failure problem. scanning electron microscopy (SEM)/transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDX), X-Ray transmission inspection, epoxy resin filling/polishing were used to identify the possible root cause. Failure analysis results confirmed that abnormal capacitance occurred by some connecting combs. Based on the results of three ways to analysis, it was concluded that the abnormal capacitance was not due to the contamination between combs of accelerometer and the substrate, but due to the connection between some combs caused by the ICP etching ununiformity. The static capacitance and resistance test results also testified this conclusion.
Effect of Operating Temperature on the Water Removal in a Polymer Electrolyte Fuel Cell
Authors: Shi Wanyuan , Oshima Nobuyuki , Saha L. Kumar , Kurihara Eru
Published: June 2009

In order to investigate the effect of operation temperature on the liquid water removal in the polymer electrolyte fuel cell, a one-dimensional steady state mathematical model was developed for the cathode gas diffusion layer (GDL). Numerical results indicate that liquid water saturation significantly increases with increases in the operating temperature of the fuel cell because the capillary pressure in the hydrophobic GDL decreases with increasing temperature. An elevated operating temperature has an undesirable influence on the removal of liquid water inside the GDL. A reported peculiar phenomenon in which the flooding of the fuel cell under a high operating temperature and an over-saturated environment is more serious in a GDL combined with a micro-porous layer (MPL) than in a GDL without an MPL (Lim and Wang, Electrochimica Acta, 49, pp. 4149–4156, 2004) is explained based on the present analysis.
Microfluidic Devices for Rapid Protein Separation
Authors: Fan Z. Hugh , Das Champak , Moreira Cesar , Olivero Daniel , Chen Hong
Published: June 2009

We present our investigation of using microfluidic devices for rapid protein separation. The devices were made from cyclic olefin copolymers that have high optical clarity and high glass transition temperature. Protein separation was achieved by using isoelectric focusing (IEF) and polyacrylamide gel electrophoresis (PAGE). A laser-induced fluorescence (LIF) imaging system was developed to detect proteins while they migrated under an electric field. IEF was carried out in a separation medium consisting of carrier ampholytes and a mixture of linear polymers. Dynamic coating of the linear polymers prevented proteins from adsorption and suppressed electroosmotic flows. PAGE was achieved in twenty-nine parallel channels. In addition, we integrated IEF with PAGE in a microfluidic device for two-dimensional protein separation.
The Effect of Duration of First and Second Anodization Steps on the Ordering of Nanopores in Anodic Aluminum Oxide Templates Achieved by Three Step Anodic Oxidation Process
Authors: Abdollahzadeh M. , Parvaini-Ahmadi N. , Nasirpouri F.
Published: June 2009

We report on the enhancement of naturally-occurred self ordering of nanopores in anodic aluminium oxide (AAO) membrane by performing three-step anodic oxidation process. Naturally-occurred self ordering of nanopores in anodic aluminium oxide (AAO) membrane has brought it into the applications of template for fabrication of nanoscale materials. Three-step anodic oxidation method was used to achieve self-ordering of nanopores. The effect of duration of first and second steps on the ordering of nanopores was investigated. The current-time curves recorded during anodization elucidate an almost same behavior for all three steps. Scanning electron micrographs (SEM) show hexagonally arranged 45 nm pores in a manner which contribute into the formation of highly ordered areas, called domains. Larger ones are clearly observed over the surface, for samples with longer first and second anodization steps.
CMORE: Fast Track From Lab to Fab
Authors: Hermans Lou , Borzi Raffa
Published: June 2009

Within the CMORE program IMEC translates proven, Si technology based device concepts and process flows in industrially and commercially viable products and manufacturing flows. Si based IC processing technologies are, and will continue for a long time to be at the basis of many product innovations. Miniaturization and integration have proven to be powerful tools for the conception of novel products. These technologies are usually referred to a “Heterogeneous Integration” or “More Then Moore” in contrast to the pure CMOS scaling referred to as “More Moore”. Many of these new products combine high performance, multiple functions and compactness with consumer price levels. In other cases, miniaturization leads to unprecedented performances, resulting in products which were not feasible before. New device concepts are often generated at university, governmental or industrial laboratories. Although these environments are very well suited for proving technical feasibility, they are often less well equipped and organized for product development and the development of corresponding Si processing flow. On the other hand the prime focus of Si or MEMS foundries, be it merchant or captive, is wafer throughput, resulting in little interest for allocating processing capacity to product and process development, when product market acceptance still has to be proven and high volume production is still questionable. In addition development activities introduce risks on contamination and equipment failures leading to a reduction of the fab capacity. This gap between “proof-of-concept” and volume manufacturing offers new opportunities for R&D fabs traditionally active in CMOS scaling. These “development and prototyping” fabs have the infrastructure, processing know-how and procedures in place to efficiently translate device concepts into products and to develop industrially viable fabrication processes. In addition they have the flexibility and experience to introduce very quickly new materials and associated equipment, while keeping in mind compatibility with the industrial foundry environment, where final production will take place. Close cooperation with material and equipment suppliers is very important in that respect. In many projects executed at IMEC, wafer scale interconnects and/or wafer scale packaging are important aspects of the final device and therefore should be included from the start of the project. In this paper the IMEC approach and capabilities will be presented and illustrated with a number of past and ongoing projects.
Micro-Channel Haemo Dialyser
Authors: Jovanovic Goran N. , Anderson Eric K. , Warner-Tuhy Alana R.
Published: June 2009

The hollow fiber based haemo dialyzer made and extremely important impact in haemo dialysis practice in the last three decades. Many people with renal diseases were able to improve their life expectancy and maintain a somewhat improved health-lifestyle. With the prospect of doubling the number of renal patients in Europe and North America by 2020, and expected improvement of health care in developing nations current dialysis treatment models and practices need new approaches and above all new technical solutions. It appears that the hollow fiber technology has met technical limitations in further development of dialysis practices. The most obvious limitations are: i) high flow rate of dialysate with respect to blood flow rate and associated cost of dialysate, ii) inability to scale down the size of the hollow fiber dialyzer for pediatric use, or everyday nocturnal dialysis in adults without dramatic reduction of dialyzer efficiency, and iii) inability to increase the overall mass transfer rate and thus reduce the cost of both dialyzer and dialysate used. Microchannel haemo dialyzers with flat membranes, developed at Oregon State University, holds many promises that are pertinent to the needs of renal patients and healthcare providers.
A New on Chip Nanomechanical Testing Concept Applied to Brittle and Ductile Thin Films Materials
Authors: Pardoen Thomas , Safi Asmahan , Coulombier Michae¨l , Carbonnelle Pierre , Raskin Jean-Pierre , Gravier Se´bastien
Published: June 2009

A novel, versatile concept of micromachines has been developed to measure the mechanical response of films, beams or tubes, with thickness ranging between 10 to 1000 nm. Its capacity to study large strains and fracture is one of its key advantages. This new technique has been used to characterize the elastic modulus and fracture stress of two types of brittle films: polysilicon and silicon nitride. The Young’s modulus agrees with the literature data. The fracture stress of polysilicon is shown to increase with decreasing specimen surface size, in agreement with the recent literature. In addition, uniaxial tensile tests have been performed on 210 nm-thick Al films up to fracture. These results show that large ductility can be obtained in very thin freestanding films, which is important for many micro- and nano-systems developments.
Design of a Non-Powered MEMS High G Shock Sensor
Authors: Wang Y. P. , Hsu R. Q. , Wu C. W.
Published: June 2009

Conventional shock sensors typically use mechanisms such as cantilever beams or axial springs as triggering devices. Reaction time for these conventional shock sensors are either far too slow or, in many cases, fail to function completely for high G (>300G) applications. In this study, a non-powered MEMS high G shock sensor with a measurement range of 3,000–21,000 G is presented. The triggering mechanism is a combination of cantilever and spring structure. The design of the mechanism underwent a series of analyses. Simulation and test results indicated that a MEMS high G shock sensor has a faster reaction time than conventional G shock sensors that use a cantilever beam or spring mechanism. Furthermore, the MEMS high G shock sensor is sufficiently robust to survive the impact encountered in high G application where most conventional G shock sensors fail.
A Flexibly Single-Point Force Sensor
Authors: Zhou Gaofeng , Zhao Yulong , Jiang Zhuangde
Published: June 2009

In the fields of gear meshing research, biomedical and physical rehabilitation, the point-meshing force between single-point meshing objects needs to be recognized or understood to obtain some important and crucial information such as force’s changing course and transient friction force at some time. In fact, the measuring space was so very narrow that the single-point meshing force couldn’t be measured out expediently. Aim at solving this problem, a flexibly single-point force sensor was brought forward and devised. This sensor was fabricated out by silk-screen printing technologies. At the same time, the performance indexes of this sensor were measured and calculated, too. Testing parameters were minutely discussed and analyzed. Results showed that the performance indexes of the flexibly single-point force sensor could satisfy the actual measuring requirement of single-point touching objects.
Transport of Hydrogen Molecules in Single-Walled Carbon Nanotube
Authors: Oh Kyung Su , Kim DongHyun , Park Seungho , Kwon Ohmyoung , Choi Young Ki , Lee Joon Sik
Published: June 2009

Carbon nanotubes are considered as promising nanoscale materials because of their unique structural, mechanical, and electronic properties. From the unique structure of long seamless cylindrical shape, it would be applied as effective nano-channels for mass transfer and relevant container for hydrogen molecules. We study hydrogen transport mechanisms in single-walled carbon nanotube (SWNT) for various chiral indices and different peculiarities, using the molecular dynamics simulation and quantum mechanics. The behavior of hydrogen molecules (H2) inside a SWNT is analyzed using mean-square displacements. From the quantum mechanics, also, the electronic density of SWNT is calculated for verifying the smooth characteristics of inner surfaces of nanotubes.
Stress Distribution on Open-Ended Carbon Nanotubes
Authors: Momeni Kasra , Alasty Aria
Published: June 2009

The stress distribution on open-ended Carbon Nanotubes (CNTs) embedded in a composite material is considered in this work and an analytical solution for the stress distribution has been obtained. The effects of CNT’s thickness and CNT’s length on the distribution of stress have been investigated. To find the governing relations, continuity equations of the axisymmetric problem in cylindrical coordinate (r,θ,z) are used. Under some assumptions, the governing equations are solved and by using constitutive equations and applying the boundary conditions, an equation which relates the stress applied to the representative volume element with the stress distribution on the CNT, has been found. The analytical solution has been applied to three different CNTs. The results for the open-ended CNTs have been compared with the results for closed-ended ones.
Study on Precision Positioning System of Two-Dimensional Platform Based on High-Speed and Large-Range
Authors: Yang Chuan , Zhang Zhi
Published: June 2009

A two-dimensional ultra-precision positioning system with high-speed and large-range which can be used for micro-nanometer machining has been studied out in this paper. Macro and micro moving system are used to meet the demands of ultra-precision positioning with high-speed and large-range. According to the demands of macro moving system, a valid control of fuzzy-neuron self-adaptive and weighted PID control algorithm with high speed and high precision is proposed. The experimental results show that the error of repeated positioning accuracy is less than 1 μ m for a random point within the range of 300mm by 300mm under the design load for a carrying test-bed with carrying area of 250mm by 250mm. According to the demands of micro moving system, self-adaptive and fuzzy reasoning PID control system based on neural network is studied for the first time. The experimental results show that repeated positioning accuracy is less than 100nm.
Fabrication of Multilayer Tubular Nanoporous Ceramic Membranes via Gel-Casting Followed by Dip-Coating
Authors: Ahmadian Namini P. , Babaluo A. A. , Akhfash Ardestani M. , Jannatduost E. , Peyravi M.
Published: June 2009

Multilayer tubular nanoporous ceramic membranes were successfully prepared via gel-casting followed by dip-coating. Tubular alumina porous support systems were manufactured by gel-casting method with pore size in the range of 100–600 nm. Interlayer and top-layer were fabricated with appropriate thickness, morphology and pore size distribution via dip-coating of submicron and nano alumina slurries respectively. The effects of the several parameters such as: solid content, dipping time, vacuum pressure, heating rate and number of coated layers on the structural properties of the prepared nanoporous ceramic membranes were studied to get an appropriate pore size and defect-free surface and then the optimum condition was presented. The morphology and surface quality of nanoporous ceramic membranes were investigated by optical microscopy (OM) and thickness of fabricated interlayer and top-layer were examined with scanning electron microscopy (SEM). Mercury porosimeter measurements were performed to determine the open porosity, pore size and pore size distribution (PSD) of nanoporous ceramic membranes.
Total Internal Reflection (TIR) Lens Design for Surface Mount Techonology (SMT) LED Application
Authors: Joo JaeYoung , Woo Do Kyun , Lee ChaBum , Lee SunKyu
Published: June 2009

In this paper, Total Internal Reflection (TIR) lens for a micro optical LED application is proposed. The aim of this paper is to design TIR lens in collimating light emitted from a surface mount technology (SMT) LED. To satisfy current technical needs, it was designed to have both thickness and diameter less than three millimeters with eleven facets where light refracts and reflects. Overall geometry of the TIR lens is numerically calculated and designed in Matlab and the central hyperboloid is designed through Code V. Manufacturability of TIR lens has been obstructing its realistic LED application because of its limitation of size. In this study, we have considered this issue and found the optimized each facet angles in which ultraprecision diamond turning is applicable. Typical blue SMT LED was modeled in LightTools to verify the decrease of solid angle. After designing, the solid angle of a LED was reduced from 120° to 20° while loosing source energy about 52%. The solid angle varies with respect to its distance from the source. The simulation results show collimation efficiency of the designed lens.
Design and Analysis of a Novel MEMS Variable Capacitor for RF Applications
Authors: Rao Qing , Yao Jun , Zhang Li , Wang Dajia , Yang Mohua
Published: June 2009

A novel electrostatic RF MEMS variable capacitor consisting of a suspended top plate and two fixed bottom electrodes is presented. The fixed bottom electrodes are constructed by an inner fixed plate and an outer fixed plate. The inner fixed bottom plate is designed to provide electrostatic actuation for capacitance tuning and the outer one is coupled with the top plate to form a variable capacitor. The mechanical suspension of the top plate is served by four L-shaped cantilever beams, the spring constant of which has been analyzed. The characteristics of the proposed device have been analyzed through FEA software IntelliSuite and HFSS, and an extended tuning range of 78.9% is obtained. The achievable pull-in voltage is 20.2V. This capacitor operates over a wide frequency range from 1GHz to 20GHz with the return loss lower than 0.16 dB. Its quality factor is 119 at 5GHz when the applied voltage is zero.
Thermally Responsive Aptamer Surfaces for Microfluidic Sample Preparation
Authors: Nguyen ThaiHuu , Lin Qiao
Published: June 2009

For many bioanalytical systems, the quality of the sample under scrutiny greatly affects the success of its analysis by the analytical instrument. Thus, sample preparatory techniques such as solid-phase extraction (SPE), purification and concentration are used to improve the quality of the sample before introduction into the equipment. This work overviews our effort in developing microdevices which exploit thermally responsive aptamers for biomolecular sample extraction, purification and concentration. We demonstrate the feasibility of this approach with a model system which consists of an adenosine monophosphate (AMP) analyte and adenosine triphosphate derived aptamer. Through systematic experimentation, we demonstrate the extraction and enrichment of AMP at physiologically relevant concentrations, release of AMP and regeneration of the aptamer through thermal stimulation, and detection of AMP by either fluorescence or mass spectrometry. In addition, completely aqueous operation of the device eliminates the use of potentially harsh reagents.
Finite Element Analysis Based Design Optimization of Exciting Efficiency for Micromachined Piezoelectric Transducer
Authors: Cai Chenguang , Chen Quayle , Zeng Dujuan , Deng Fei , Salo Antti , Xu Leon
Published: June 2009

This paper presents a design optimization of a membrane-based ultrasonic piezoelectric transducer using micromachining by finite element simulation. The transducer can be used to generate ultrasound using the piezoelectric film to excite the vibration of the transducer membrane. The objective is to maximize the vibration magnitude of the membrane by optimizing the structure of the transducer, when the exciting signal is fixed. The size and the shape of the piezoelectric film were selected as the design parameters to optimize the structure of the transducer. Based on the theoretical analysis, it is found that the absolute values of the stresses in the center and the boundary of the diaphragm are greater than that on the other regions of the film, with the directions of the stress on center and boundary opposite to each other. In order to achieve the maximum exciting efficiency, the discrepancy in the stresses between the center and the boundary on the diaphragm should be maximized. In this paper, totally four different piezoelectric film structures are analyzed for optimizing the exciting efficiency of the transducer. The finite element models of the transducer were created using ANSYS. The simulations based on the three design options were performed; and through the comparison of the simulation results, the optimal structural parameters of the piezoelectric film are identified. Finally, the direction of the design improvement for the exciting efficiency of the transducer is provided.
Fabrication of Phase Reflection Sawtooth Gratings Optimized by Scalar and Vector Way by Using Diamond Cutting
Authors: Lee ChaBum , Kuriyagawa T. , Kim TaeJun , Lee SunKyu
Published: June 2009

This paper presents optimization of phase reflection sawtooth gratings with a period of 2.0 μm and a depth of 0.2 μm based on the Fourier transformation (FT) and the rigorous coupled wave analysis (RCWA). And its fabrication on oxygen free Cu and electroless Ni-coated surfaces by using diamond cutting in a shaping process whose toolpath is interfered to provide smaller period. The diffraction efficiencies were estimated 100% for FT, 83.0% and 79.0% for TE and TM polarization of the incident light at a depth of 0.2 μm. It was found that electroless Ni-coated surface had better performance in terms of machining and optical functionality. From optical testing, the diffraction efficiencies were measured 84.0% and 84.4% for TE and TM polarization, respectively.
Investigation of Temperature-Dependent Droplet Formation of Nanofluids in Microfluidic T-Junction
Authors: Nguyen Nam-Trung , Murshed S. M. Sohel , Tan Say-Hwa
Published: June 2009

The study on the control of microdroplet formation and manipulation is very important due to the potential applications of droplet-based microfluidics in various important fields. Experimental investigations on thermally controlled droplet formation and size manipulation of deionized water and nanofluids in a microfluidic T-junction are reported in this paper. The heater temperature affects the droplet formation process. Nanofluids are found to exhibit different characteristics in droplet formation and size control with the temperature. Addition of spherical-shaped TiO2 (15 nm) nanoparticles in deionized water results in much smaller droplet size compared to the cylindrical-shaped TiO2 (10×40) nm) nanoparticles. Other than nanofluid with cylindrical-shaped nanoparticles, the droplet size was found to increase with increasing temperature.
Uncertainty Analysis in Bioheat Transfer Modeling for Treatment Planning of Nano-Cryosurgery
Authors: Deng Zhong-Shan , Liu Jing
Published: June 2009

The ultimate aim of cryosurgery is to exactly kill all tumor cells within a closely defined region. For this purpose, we recently proposed an effective approach to perform conformal cryosurgical treatment of tumors by adjuvant use of nano-particles. Such a nanoparticle-enabled cryosurgical modality is termed as nano-cryosurgery. In this study, the uncertainties for the predicted temperatures of tissues in nano-cryosurgery due to approximate parameters were investigated. Contributions of uncertainties from the tissue area permeated with nanoparticles, the concentration of nanoparticles, and the thermal parameters of tissues were respectively analyzed, and the uncertainty limits for temperature distributions in these cases were also estimated. The uncertainty analysis presented in this study is expected to serve as a significant guide for performing a highly efficient and also completely safe nano-cryosurgical treatment.
Thermal Control for Droplet-Based Microfluidics
Authors: Nguyen Nam-Trung
Published: June 2009

This paper presents our recent works on thermal control for droplet-based microfluidics. Temperature dependent properties of liquids have been use for actuation and many other applications in droplet-based microfluidics. In analogy to an analog/digital electronic circuits, a droplet-based microfluidic system consists for three main subsystems: droplet formation (analog/digital converter), droplet manipulation (digital processing) and droplet merging (digital/analog converter). This paper will present our recent achievements in thermal control of droplet formation in different configurations such as T-junction and cross junction with integrated microheaters. Furthermore, results on droplet switching will be presented. The droplet switch represent basic logic gate that can be used to construct a more complex droplet-based digital network. Thermocapillary actuation of microdroplets in one-dimensional and two-dimensional microfluidic platforms will be presented. Both numerical and experimental results will be presented in this paper.
Near-Field Radiative Heat Transfer Between Materials With Dielectric Coatings
Authors: Fu Ceji , Tan Wenchang
Published: June 2009

Radiative heat transfer between materials with dielectric coatings is numerically studied based on the fluctuational electrodynamics and the fluctuation-dissipation theorem. The results show that whereas a dielectric coating (SiC) enhances the far-field radiative heat transfer between two bulk metals, it will suppress the radiative heat transfer in the near-field and the suppression is only for the s-wave contribution. The total radiative heat flux continuously decreases as the coating thickness increases up to 1 μm. A further increase in the coating thickness will cause the total radiative heat flux to increase slightly before it saturates. In addition, a much smaller coating thickness than the coating’s skin depth is enough to significantly change the total radiative heat flux in the near-field region. On the contrary, a thin dielectric coating that supports surface polaritons can greatly enhance the radiative heat transfer between a metal and a dielectric in the case that the coating is on the metal. The large enhancement is due to surface polaritons excited on the two surfaces of the air gap boundaries.
Study for the Interface Thermal Resistance of Metal-Dielectric Layers
Authors: Chien Heng-Chieh , Yao Da-Jen , Hsu Cheng-Ting
Published: June 2009

In this Study, we measured the interface thermal resistance between metal/dielectric layers using a sandwiched structure. Common used metal thin films in MEMS including chromium, nickel, aluminum, titanium, and platinum, were sandwiched in between two PECVD SiO2 layers. Measured values of the interface thermal resistance distributed over the range of 2.5∼3.8×10−8 m2K/W. The continuum two-fluid model was served to provide some reasonable physical insight into the cause of metal/dielectric interface thermal resistance, and also to verify our measurement data. The estimated values are much smaller than the measured values. Moreover, the adhesion tests were implemented to verify the interrelation between the interface adhesion force and the measured interface thermal resistance. The results show the interface thermal resistance is very insensitivity to the adhesion force.
Growth and Characterization of PZT Thin Films
Authors: Bao Daqun , Zhang Yi , Guo Hang
Published: June 2009

This paper presents the growth and characterization of PZT thin films by using the sol-gel technology. In this paper, we study the influences of annealing process and different substrates on the orientation and crystalline quality of PZT thin films. The crystallographic structures are tested by using X-ray diffractometer (XRD), and the residual stresses of PZT thin films are obtained by calculation from a derived stress-strain equation in XRD analysis. Moreover, surface morphology and microstructure of the films are investigated by using AFM and SEM, and the polarization hysteresis of PZT thin films is measured by using a Sawyer Tower circuit. The results show that PZT thin films prepared by using the sol-gel method have good properties and can be used for developing PZT-based micro and nano devices.
Bubble Dynamics on Nanostructured Cu Surfaces
Authors: Li Chen , Koratkar Nikhil , Peterson G. P.
Published: June 2009

Nucleate boiling performance was enhanced up to an order of magnitude through direct deposition of Cu nanorods on a planar Cu surface. The methodology that enables order of magnitude improvement in boiling performance without fabricating complicated surface structures or changing the working fluid will have broad impact on metal-liquid type two-phase heat exchangers. In this study, discussion was focused on bubble dynamics on the nanostrucured Cu surfaces. We observed striking differences in bubble dynamics through nucleation boiling process for the nanostructured surface including smaller bubble diameters, higher release frequencies and nucleation site density, and large fluctuations in bubble diameter prior to release. These differences during the boiling process are responsible for the enhanced heat transfer. High quality images were captured through a well-designed visualization system, which comprises of a high-speed charge-coupled device (CCD) camera, microscope and data acquisition system. This visualization study aims to quantitatively study the bubble dynamics on the nanostructured Cu surfaces.
An Integrated Approach to High-Speed Probe-Based Nanofabrication: SPM Imaging
Authors: Yan Yan , Zou Qingze
Published: June 2009

In this article, we propose an integrated approach to achieve high-speed nano-positioning for high-speed atomic force microscope (AFM) operations in applications such as probe-based nanofabrication. The development of AFM technology enabled the “bottom up” approach to design and create nanostructures and nanodevices. The throughput of the probe-based nanofabrication, however, is limited by the challenges in positioning the probe at high-speed. In AFM operations, nano-positioning of the probe in 3-D (both lateral x – y and vertical z axes) is needed. High-speed, large-size AFM operation is challenging because in high-speed lateral scanning of the AFM operation at large positioning range, large positioning error of the AFM probe relative to the sample can be generated due to the adverse effects—the nonlinear hysteresis and the linear vibrational dynamics of the piezotube actuator. In addition, vertical precision positioning of the AFM probe is even more challenging (than the lateral scanning) because the desired trajectory (i.e., the sample topography profile) is unknown in general, and the probe positioning is also effected by and sensitive to the probe-sample interaction. The main contribution of this article is the development of an integrated approach that combines advanced control algorithm with an advanced hardware platform. The proposed approach is demonstrated by implementing to AFM imaging of a large-size (50 μm) calibration sample at high-speed (50 Hz scan rate).
Relationship Between Distance of Photonic Crystal Rods Array and Wavelength of Light Propagating in Right-Angular, Cross, and Y-Shapes Waveguide
Authors: Lin Meng-Ju
Published: June 2009

Photonic crystal is widely used in optical communication. Waveguide is one of important components used in optical communication. The performance of right-angular, cross, and Y shapes photonic crystal waveguide used in optical communication is investigated. Material used for photonic crystal is GaAs. Shape of photonic crystal rod is cylindrical rod. These rods are arranged to become matrix with constant distance. In the photonic crystal matrix, some rods are removed to form waveguide channel. Three shapes of waveguides are discussed. They are right-angular, cross, and Y shapes. The relationship between distances of circular photonic crystals and wavelength in propagation is discussed. Due to coupling of multi physical phenomena and complex geometry, a finite element method software called COMOSL is used to analyze performance of waveguide under different wavelength of light. It is found under different distance of photonic crystal rods array and wavelength, light could propagate along waveguide successfully or lost energy and decay. From results analyzed by COSMOL software, numerical data are obtained to classify light being able to pass waveguide successfully or not. By neural network method, equations between crystal rods array distance and wavelength to decide whether light can propagate through waveguide successfully or not are derived. They can be used to determine performance of light propagating in waveguide. For Y shape waveguide, bifurcation phenomena of light propagate in different channel of Y shape branch is found. It is found under different crystal pillar distance the light of different wavelength would propagate in one of the branch of the Y shape channel. The longer wavelength lights pass the upper channel and the shorter pass the lower. The results show that the bifurcation happens at the tendency if pillar distance increases the bifurcation wavelength also increases. From neural network method, equations to decide light propagate to upper or lower branch of Y shape waveguides are also obtained.
Interactions of Liquid Plugs in a Pulsating Heat Pipe
Authors: Qu Wei , Qu Chong , Zhou Yan
Published: June 2009

The interactions of two plugs in a pulsating heat pipe are important to mechanism and operation of the multi-plugs. Based on the experimental observation, the control volume of a pulsating heat pipe with two capillary passages and two liquid plugs is modeled. The operations of the two liquid plugs were described and solved by differential equations. The loci and velocities of the oscillating and moving liquid plugs were obtained. The results show that the bigger capillary diameter, the lower filling rate, the higher heating power and the initial stronger perturbations can all lead to faster movement of the liquid plugs, and it is better to the heat transfer. When the heating power is lower, the liquid plugs do not coalesce. While if the heating power is higher, then the liquid plugs may coalesce, further to form the single liquid plugs or the circular flow pattern. The results can explain the experimental visualizations qualitatively the interactions between the liquid plugs.
Experimental Performance of a Nanofluid Pulsating Heat Pipe
Authors: Qu Wei , Qu Chong , Feng Jianchao
Published: June 2009

The startup and operating performances of a nanofluid pulsating heat pipe are experimented. When the working fluid is selected as nanofluid instead of the base working fluid, the pulsating heat pipe can work at lower heating loads and start up more quickly and the thermal resistance between the heating section and the cooling section significantly decreases. For the nanofluid and base working fluid, the operating temperature increases with the heating load, the thermal resistance of pulsating heat pipe decreases with the operating temperature. The inclination angles of pulsating heat pipe as 30°, 60°, or 90°, have little effects on heat transfer performance. Under a vertical bottom heating mode of 100 watts and at the operation temperature of 110 °C, the thermal resistance of TiO2/H2O nanofluid pulsating heat pipe can be 0.11 °C/W, while it is 0.23 °C/W for the base working fluid. The mechanisms that the nanofluid pulsating heat pipe has better performance are tentatively explained as, the nano particles can form many micro nuclear centers for the boiling, and can lead to several heat transfer enhancement.
Fabrication of Macroporous on No-Mask Silicon Substrate for Application to Microsystems
Authors: Nagayama Gyoko , Ando Ryuji , Muramatsu Kei , Tsuruta Takaharu
Published: June 2009

We applied the anodic etching (i. e. photo assisted electrochemical etching) to the n type silicon substrate of orientation (100) without masking to fabricate macropores penetrated Si substrate. The anodic etching conditions of the macroporous formation were discussed and the effects of the resistivity, voltage, current density, electrolyte concentration and illumination etc. on the pore size and the porosity were investigated. The pores in high aspect ratio through the cross section of the silicon wafer were obtained with polishing and RIE (reactive ion etching) from the back side. It is found that the pore size at the back side is about 1.5 to 2 times larger than that of the front side. Also, as one example of the applications of porous silicon to microsystems, we demonstrate the results obtained in a micro fuel cell system using a porous silicon membrane (PSM). The PSM was fabricated by a porous silicon wafer which was filled with Nafion dispersion solution with ultrasonic vibrations. It was used as a proton conduction membrane by assembling into the H2 / air feed fuel cell at ambient conditions using conventional electrodes. We found that the Nafion filled PSM worked well and a maximum power density of 89.2 mW/cm2 were achieved under the flow rate of 100ml/min for H2 and 200ml/min for air.
Molecular Dynamics Simulations of Heat Conduction in Thin Film With Nano-Holes
Authors: Miyazaki Koji , Nagai Daisuke , Tsukamoto Hiroshi
Published: June 2009

We carried out molecular dynamics simulations (MD) of heat conduction in Si thin film and Si films with a nano-hole to represent the nano-structure, in order to investigate the mechanism of the thermal conductivity reduction of nano-structured materials. The Stillinger-Weber potential is used in this study. Different temperatures are applied at the both sides of boundaries of the calculation domain in the z-direction, and periodic boundary conditions are applied in the x and y directions. The calculated temperature profile of a Si thin film of 10.86nm thickness is compared to that calculated by using the phonon Boltzmann transport equation (BTE). These agreed reasonably well with each other, and the phonon mean free path of Si is estimated to be several tens of nanometers. Molecular dynamics simulation of Si at the uniform temperature of 800K is also carried out. Phonon dispersion curves are calculated by using the time-space 2D Fourier transform. The phonon modes at high frequency are not present in nano-structures of Si. We discuss the mechanism of the reduction of the thermal conductivity of nano-structured material on the atomic scale.
Relaxor Properties and Conduction in TlInS2 Crystals
Authors: Sardarly Rauf , Samedov Oktay , Nadzhafov Arzu , Salmanov Famin , Abdullayev Adil , Bayramov Azad
Published: June 2009

The density of states at the energy levels associated with radiation-induced defects, the localization length of a defect center, and the hopping distance of charge carriers are determined in a TlInS2 crystal. It is demonstrated that, by varying the dose of gamma radiation, it is possible to control the dielectric properties of ferroelectrics and to attain a stable relaxor state. In the temperature range of existence of this state, charge carriers execute tunneling from electron levels in the band gap through potential barriers created by an incommensurate superstructure of the TlInS2 crystal. The considerable interest expressed by researchers in this class of ferroelectrics stems from the fact that these materials are very promising for use in data-storage systems. It will allow creating the processor on the uniform semi-conductor chip with the device for electronic reading and recording of the information from magnetic materials.