bluuebunny/crossref_metadata_2025 huggingface dataset:
Gas Bubble Sizes Formed in Liquids at Different Resonant Frequencies
Authors: Cheng Chiang Ho , Chang Chia Lan , Chan Tsung Hsing
Published: September 2009

The present research applies the microelectronmechanical system (MEMS) technology to design and fabricate a novel micro-bubble generator by using a piezoelectric actuator. The main structure of the proposed generator adopts an annular piezoelectric ceramic which is coupled with a nickel nozzle plate. In the experiment, a flow visualization setup employs a high magnification microscope and a high speed charge coupled device (CCD) camera to photograph the time evolution of meniscus shape of gaseous bubbles dispensed from the micro-bubble generator. The bubble formation process including the effects of inlet gas pressure as well as driving voltage and resonance frequency on generated bubble size is also discussed in the study.
DC-Biased AC-Electrokinetic Mixing: A Mechanistic Investigation
Authors: Ng Wee Yang , Lam Yee Cheong , Rodríguez Isabel
Published: September 2009

This paper presents an experimental investigation on the DC-biased AC-electrokinetic (ACEK) flow vortex in a rectangular microchannel. This is a new flow phenomenon in AC-electrokinetics and had been successfully utilized for microfluidic mixing as reported in our previous work. The microchannel is aligned parallel to a pair of energized coplanar microelectrodes such that the generated flow vortex is perpendicular to the pressure-driven flowing samples. With the application of a DC bias AC voltage, incipient Faradaic reactions occur above the electrodes and thus producing ions and creating a net dominant flow vortex. Further investigation to understand the generation of the DC-biased ACEK flow was conducted. This is performed by direct visualization of such flow vortex formation from the cross-section of a rectangular microchannel.
Gas Permeation in Polydimethylsiloxane In Situ Monitoring by Silicon Pressure Sensors
Authors: Yang Lung Jieh
Published: September 2009

This paper proposes a new way to detect the gas-leakage through PDMS. We use PDMS instead of Pyrex #7740 glass to seal the backside V-grooves of silicon pressure sensors. We put the packaged sensor into a pressurized chamber with CO2 at 300 psi. By observing the output voltage of the pressure sensor, the time history for CO2 permeating into the sensor cavity was easily found. In experiments, we use several PDMS membranes with different thickness, from 45 to 2000 μm, to package the pressure sensors and investigate the gas-leakage of PDMS. The gas leaking through PDMS is shown to be governed by diffusion mechanism, and the diffusion coefficients derived from CO2 leaking history is 2.2×10-9 m2/sec, matched with the previous work.
Analysis of Ionic Transport Interaction between Soft Smart Hydrogel and Solution in BioMEMS Channel
Authors: Luo Rong Mo , Li Hua , Ng Teng Yong
Published: September 2009

A multiphysics model is presented to simulate the ionic transport interaction between the smart pH-electric-sensitive hydrogel and solution in micro-scale channel for BioMEMS application, when it is immersed into a pH buffer solution subject to externally applied electric field. It is called the multi-effect-coupling pH-electric-stimuli (MECpHe) model, and covers chemo-electro-mechanical coupled effect and the fixed charge density associated with the buffer solution pH and electric potential. The model enables us to predict the distributive diffusive ionic species concentrations and the distributive electric potential in both hydrogel and surrounding solution as well as the fixed charge density and the displacement of hydrogel, especially to study the ionic transport interaction between the soft smart hydrogel and solution in the micro-channel. By the MECpHe model, the equilibrium response of the smart hydrogels is simulated to the interaction with the solution pH and electric coupled stimuli. Influence of the several key parameters including the externally applied electric voltage and solution pH is discussed in detail on the distributions of ionic species concentrations and electric potential for the ionic transport systems in micro-scale channel.
Transport of Water and Particles in Microfluidics Devices Lithographically Fabricated Using Proton Beam Writing (PBW)
Authors: Whitlow Harry J. , Wang Li Ping , Gilbert Leona
Published: September 2009

Proton beam writing (PBW) is a MeV ion beam lithography technique that has gained interest in many biological applications such as fabricating microfluidic devices for Lab-On-a-Chip (LOC) applications where capillary forces are important for fluid flow. PBW has a unique capability of being able to direct-write patterns in thick (1-30µm) polymer resist layers with straight vertical sidewalls. It can be used to prepare master stamps and moulds for mass production in polymeric materials. A recent development, where the direct writing of an entire pattern element is carried out in parallel makes PBW especially well suited for Bio-MEMS LOC applications. In this study we have examined the flow dynamics using video microscopy of deionised water in fluidic channel patterns fluid reservoirs, capillary sections and a capillary pump written by PBW. The video microscopy data also demonstrated that the wetting behavior of the surface strongly influences the dynamics of fluid flow. This makes new approaches for LOC fabrication feasible and powerful.
Modeling of Performance of Single Elastic Capsule in Time-Dependent Two-Dimensional Microchannel Flow
Authors: Ma Gang , Li Hua , Ng Teng Yong
Published: September 2009

The mechanical behavior of capsule in microscale flow is fundamentally important in physiology, pharmaceutical or agricultural industries, fluid mechanics and physics. In the present paper, the performance of two-dimensional capsule in time-dependent microchannel flow is investigated by a numerical simulation method, which combines the finite volume method for solving the fluid problem with the front tracking technique for capturing and tracking the capsule membrane. Initially circular capsule is considered in the simulations, and the capsule is modeled as liquid medium enclosed by a thin membrane, for which linear elastic properties are taken into consideration. The membrane mechanics is adopted to calculate membrane-fluid interaction, based on which the solution of fluid problem is obtained. The capsule membrane is advected explicitly according to fluid velocity results. Results of capsule position, capsule moving velocity, capsule shape, velocity field of fluid inside and outside the membrane can be obtained from the numerical simulations. Based on these results, the effects of time-dependent background fluid on capsule behavior are studied.
Use of Micro Synthetic Jet Actuators for Boundary Layer Flow Control
Authors: Lin Jing Chuen , Yang An Shik , Tseng Li Yu
Published: September 2009

The main purpose of active flow control research is to develop a cost-effective technology that has the potential for inventive advances in aerodynamic performance and maneuvering compared to conventional approaches. It can be essential to thoroughly understand the flow characteristics of the formation and interaction of a synthetic jet with external crossflow before formulating a practicable active flow control strategy. In this study, the theoretical model used the transient three-dimensional conservation equations of mass and momentum for compressible, isothermal, turbulent flows. The motion of a movable membrane plate was also treated as the moving boundary by prescribing the displacement on the plate surface. The predictions by the computational fluid dynamics (CFD) code ACE+® were compared with measured transient phase-averaged velocities of Rumsey et al. for software validation. The CFD software ACE+® was utilized for numerical calculations to probe the time evolution of the development process of the synthetic jet and its interaction within a turbulent boundary layer flow for a complete actuation cycle.
Supernatant Decanting on a Centrifugal Platform
Authors: Shih Chih Hsin , Yuan Wei Li , Lu Chien Hsing , Chiang Wei Ling
Published: September 2009

This work presents a novel approach to decant and meter supernatant on a centrifugal platform. Supernatant decanting, such as decanting plasma from the centrifuged whole blood, is an important sample preparation procedure for the whole blood bioassays. By manipulating the centrifugally induced pressure and the elastic deformation of the chamber’s plastic lid, fixed amounts of the supernatant can be decanted into the detection chamber. This approach has the advantages of low manufacturing cost and ease of operation.
Design and Fabrication of Novel Compliant Electrostatically Actuated Microvalves
Authors: Zhang Qing , Pekas Nikola , Juncker David
Published: September 2009

Electrostatically actuated microvalves are appealing candidates to build fully integrated microfluidic circuits because of the direct transduction of electrical signals into mechanical responses at low power consumption levels. Practical solutions, however, are still lacking due to their multi-layered architecture and difficulties in incorporating heterogeneous materials. In this paper, we report the design and fabrication process of an electrostatically actuated gas microvalve amenable to large scale integration for gas flow control. The device we designed consists of an upper die, containing a flexible electrode sealed by a thin elastic membrane, and a lower die, containing gas channels of trapezoidal cross-section and fixed electrodes. Each microvalve is defined by one fixed electrode spanning the floor and sidewalls of the trapezoidal gas channel and one corresponding flexible electrode suspended above the channel. In contrast to the conventional parallel-plate arrangement of electrodes, the two electrodes are approximated starting from the edges of the trapezoidal gas channel during the actuation step, which is advantageous for lowering the required actuation voltage. The upper die was fabricated by replica molding in polymeric material, the lower die was fabricated in a glass substrate by conventional microfabrication techniques, and the two dies were subsequently aligned and bonded using an adhesive layer. This reported low cost fabrication process could be implemented in any basic microfabrication facility. When a net pressure up to 1 bar was applied to the gas channel, reasonable flow rate was achieved. We also observed displacement of the flexible membrane when a DC voltage of 200 V was applied to a pair of electrodes. These preliminary results show that this microvalve is a promising candidate for integrated on-chip valving and will allow for building large scale microfluidic circuits with reduced power consumption.
An On-Chip Micro-Droplet Optical Filter Using Evanescent Wave Coupling
Authors: Yu Ye Feng , Bourouina Tarik , Liu Ai Qun
Published: September 2009

An on-chip micro-droplet optical filter based on the evanescent wave coupling by fiber taper is presented in this paper. The optical filter consists of a T-junction for micro-droplets generation and an integrated optical fiber taper for light input and output. The light is coupled into the droplet resonator when it has the same wavelengths as the Whispering Gallery Modes (WGMs) of the droplet. The coupling efficiency can be adjusted by tuning the distance between the droplet and the fiber taper using micro fluidic flow. Compared with the solid sphere or ring optical filter using fiber taper coupling, the diameter and refractive index of liquid droplet can be easily tuned, which means the resonant modes can also be tuned. The diameter of the droplet is controlled by the flow rate ratio at the T-junction. The micro-droplet optical filter also has advantages as wide wavelength tuning range, easy fabrication process, simple manipulation, and low cost, which promise for many applications in optical analysis on micro-optical-fluidic chip.
Numerical Simulation of Stretchable and Foldable Silicon Integrated Circuits
Authors: Liu Zhuang Jian , Zhang Yong Wei , Song Ji Zhou , Kim Dae Hyeong , Huang Yong Gang , Rogers John
Published: September 2009

This paper presents numerical simulation strategies for stretchable silicon integrated
circuits that use stiff thin film on elastomeric substrates. Detailed numerical simulation studies
reveal the key underlying aspects of these systems. The results indicate, as an example, optimized
mechanics and materials for circuits that exhibit maximum principal strains less than 0.2% even for
applied strains of up to ~90%. Simple circuits, including CMOS inverters provide an example that
validates these designs. The results suggest practical routes to high performance electronics with
linear elastic responses to large strain deformations, suitable for diverse applications that are not
readily addressed with conventional wafer-based technologies.
Design and Analysis of Micromixers on a Centrifugal Platform
Authors: Shih Chih Hsin , Lu Chien Hsing , Lin Chia Hui , Wu Hou Jin
Published: September 2009

This work reports a novel mixing design that can do fast, batch-typed liquid mixing on a centrifugal platform. Mixing is an important procedure for many applications related to chemical reactors and biological assays, especially in the field of microfluidics. The extremely small sizes of microchannels make it difficult to achieve turbulence to assist mixing. To overcome this problem, a meandering fluidic design on the centrifugal platform is proposed. Centrifual force promotes mixing by inducing lateral flow movement in the circular section and flow focusing effect in the bending section. The degree of mixing was studied for solutions with various viscosities under different rotational speeds. The experimental results showed that this mixer can mix microliter or nanoliter volumes of aqueous solutions within one second.
A Pendulum-Like Structure for Design of Oscillators
Authors: Chenniappan Venkatesh , Moheimani Reza , Yuce Mehmet
Published: September 2009

A novel MEMS resonator employing “capacitance-shaping” principle to generate sinusoidal signals is proposed. FEM simulations are done to study the structure. Preliminary characterizations on devices fabricated through SOI-MUMPS are carried-out to study the frequency tuning of the resonator by electrostatic actuation. Variants of the proposed structure are presented. Second order dynamical models of the devices are derived.
Separation and Manipulation of Particles Using Traveling Wave Dielectrophoretic Force
Authors: Maturos Thitima , Jaruwongrangsee Kata , Sappat Assawapong , Lomas Tanom , Wisitsoraat Anurat , Wanichapichart Pikul , Tuantranont Adisorn
Published: September 2009

In this work, we present a device for cell manipulation and separation by using travelling wave dielectophoretic force. The device consists of a 16 parallel electrode array and microchamber. The dielectrophoretic PDMS chamber was fabricated by using standard microfabrication techniques. The Cr/Au parallel electrode array of 100 µm wide and 300 nm thick was patterned on a glass slide by sputtering through microshadow mask. The polystyrene microspheres suspension in de-ionized water and red blood cells in D-mannitol solution were used as tested cells. Cells respond to the electric field in various mechanisms depending on the applied voltage and frequency of the AC signals. For 4.5 µm polystyrene, the traveling wave dielectrophoresis happened when the applied voltage was 10 V, and the frequency of the applied signals was in the range of 50 kHz-700 kHz. For 10 µm polystyrene the twDEP occurred when the applied voltage was 7 V, and frequency was in the range 30 kHz-1MHz. While the red blood cells experienced the twDEP when the applied voltage was 3 V and frequency was in the range 50 kHz-2MHz. The mixed solution containing equal amount of 4.5 and 10 µm microspheres were used for separation test. The big microspheres were moved under twDEP force when the applied voltage was 7 V, and the frequency was in the range of 25 kHz-1MHz while the small microspheres were attached to the electrodes. Therefore, the twDEP device can manipulate and separate the microspheres with different sizes, and it can be further applied for cells selection.
Performance Characterization of a Piezoelectric Micro SJA
Authors: Yang An Shik , Ro Jeng Jong , Chang Wei Han
Published: September 2009

This paper aims to explore the synthetic jet behavior for a dual-diaphragm piezoelectrically driven micro synthetic jet actuator. For a sinusoidal actuation cycle at an operating frequency of 648 Hz, the synthetic jet flow pattern was simulated and compared with the visualized image and measured centerline velocity distribution to validate the computer code. The far-field flow structure was similar to a common continuous turbulent air jet; whereas, the unsteady formation of a vortex pair was predicted in the near-field. Numerical experiments were extended to appraise performance of micro synthetic jet actuators by varying the driving voltage, width of the slot and depth of the actuator cavity.
Prediction of Burr Formation in Fabricating MEMS Components by Micro End Milling
Authors: Ali Mohammad Yeakub , Omar Mohd Aliff , Othman Khairul Irman , Hung Wayne N.P.
Published: September 2009

This paper discusses burr formation in micromilling of AISI 304 stainless steel. Chip load, cutting speed and the application of coolant were chosen as the milling parameters. Experiments were conducted using 500 µm diameter tungsten carbide end milling tool. Milling parameters and measured burr height values were analyzed and statistical models were developed for the estimation of burr height. The models showed that the chip load and cutting speed both have direct and interactive contribution to burr formation. When micromachining without coolant, the burr height increases about 40% compared to that of machining with coolant. The optimized values of chip load and cutting speed were found to be 1 µm/tooth and 78 mms-1 respectively. The predicted burr heights were 5-7% larger than that of measured values.
A Transient Simulation for Analysis of Volume Transition of pH-Sensitive Hydrogel in Micro-Channel
Authors: Zou Hua , Li Hua
Published: September 2009

Based on Donnan’s equilibrium, a simple chemo-mechanical model is developed to study the transient swelling behavior of the pH-sensitive hydrogel for design and optimization of smart hydrogel-based BioMEMS device. The model is mathematically composed of several governing equations, including Fick’s law which describes the diffusion process in the buffer solution, the fixed charge density formula associated with pH value of the buffer solution, and mechanical equation which gives the swelling ratio responding to pH. The model also considers several chemical conditions, including Donnan’s equilibrium condition which gives Donnan partitioning ratio relating to the concentrations of ionic species in the interior hydrogel and the external solution, the electroneutrality condition in the interior hydrogel and bathing solution as well. The model is capable of predicting the kinetics process of the smart hydrogel immersed in buffer solution with change in pH. The simulation of the diffusion-swelling behavior of the pH-sensitive hydrogel is presented, and the responsive deformation of the smart hydrogel to the solution pH is discussed in detail.
Fabrication of Reliable RF MEMS Switches in CPW Configuration
Authors: Sharma Jaibir , DasGupta Amitava
Published: September 2009

This paper describes a new fabrication technique for RF MEMS switches where the coplanar waveguide (CPW) is fabricated in a basin. A planar profile and good coverage at the edges in a basin is achieved by spinning and baking the sacrificial positive photoresist (PPR) in multiple steps to fill the basin. The basin structure allows an increase in the length of the membrane resulting in lower pull-in voltage and better isolation. The PPR is removed using Piranha solution (H2SO4:H2O2::3:1). Structures with the gap of about 2.5 µm and the thickness of the gold membrane varying from 1µm to 2.5 µm have been successfully realized.
Exploring the Innovational Potential of Biomimetics for Novel 3D MEMS
Authors: Gebeshuber Ille C. , Stachelberger Herbert , Ganji Bahram Azizollah , Fu Dee Chang , Yunas Jumril , Majlis Burhanuddin Yeop
Published: September 2009

A novel way to describe the complexity of biological and engineering approaches depending on the number of different base materials is proposed: Either many materials are used (material dominates) or few materials (form dominates) or just one material (structure dominates). The complexity of the approach (in biology as well as in engineering) increases with decreasing number of base materials. Biomimetics, i.e., technology transfer from biology to engineering, is especially promising in MEMS development because of the material constraints in both fields. The Biomimicry Innovation Method is applied here for the first time to identify naturally nanostructured rigid functional materials, and subsequently analyse their prospect in terms of inspiring MEMS development.
Compatibility Study of Diamond-Like Nanocomposite Thin Films with Hydrazine Propellant for MEMS Microthruster
Authors: Kundu Pijus , Ray Chaudhuri A. , Das S. , Bhattacharyya T.K.
Published: September 2009

In this paper, the etching characteristic of diamond like nanocomposite thin films materials in hydrazine has been reported. The experiments have been carried out to explore the compatibility of hydrazine as a propellant with silicon based microthruster. In the reported work, 2″ N-type (100) silicon wafer with 4-6 Ω cm resistivity were used as base material. Diamond-like nanocomposite (DLN) films are deposited on silicon substrate by plasma enhanced chemical vapor deposition (PECVD) process using siloxane or silazane based precursors or their combinations. Thickness of deposited DLN thin films is around 1 µm. DLN samples are treated in 98% hydrazine at 25 °C, 70 °C and 90 °C for different time and etch rates and subsequently the change in refractive index of the DLN films if any has been measured.
Parametric Study of Femtosecond Pulses Laser Hole Drilling of Silicon Wafer
Authors: Jiao L. , Ng Eyk , Wee L.M. , Zheng Hong Yu
Published: September 2009

Clark MXR femtosecond (fs) laser micro structuring with pulse duration of 200fs up to a wavelength of 1030nm with a nominal frequency of 1 KHz on silicon wafer was studied in air using the direct focusing technique. The three steps of laser drilling process, namely hole entrance, spatter formation and hole exit, were conducted to investigate the laser parameters such as laser power, focus position, focus lens and number of pulses and their effects on the drilling hole geometry and spatter characteristic. The results show that the minimum entrance diameter is achieved while Zf =-0.2mm. It was easier for the laser to break through the material with longer lens focus length (f=100mm). However, smaller hole was produced when the focus length was shorter. The average diameter is as small as 23µm and aspect ratio is 1:30 at laser power of 200mW.
Piezoeletric Micropump for Drug Delivery System Fabricated Using Two Optical Masks
Authors: Johari Juliana , Yunas Jumril , Majlis Burhanuddin Yeop
Published: September 2009

. In this study, a Piezoelectric Actuated Valveless Micropump (PAVM) has been designed and successfully fabricated using MEMS fabrication processes. A PZT: Pb (ZrTi) Ox (lead titanate zirconate) disc is used to actuate a silicon membrane by applying an alternating electrical field across the actuator. The resultant reciprocating movement of the pump membrane is then converted into pumping effect. Preliminary analysis of the fluidic characteristics of this micropump was performed using CoventorWare Simulator with MEMs-FSI (Fluid Structure Interaction) module to understand the working behaviour of the pump system. The pump is fabricated in a simple micromachining process with two optical masks using a double side polished silicon wafer. The tests carried out on the micropump have produced promising results to be used in the drug delivery system.
Hybrid Simulation Approach on MEMS Piezoresistive Microcantilever Sensor for Biosensing Applications
Authors: Rahim Rosminazuin A. , Bais Badariah , Majlis Burhanuddin Yeop
Published: September 2009

This paper uses a hybrid simulation approach in CoventorWare design environment which combines finite element analysis and circuit simulation modeling to obtain the optimal performance of piezoresistive microcantilever sensor. A 250 μm x 100 μm x 1 μm SiO2 cantilever integrated with 0.2 μm thick Si piezoresistor were used in this study. A finite element analysis on piezoresistive microcantilever sensor was conducted in CoventorWare Analyzer environment which incorporates MemMech and MemPZR modules. The sensor sensitivity was obtained by measuring resistivity changes in piezoresistive material in response to surface stress changes of microcantilever. The simulation results were later integrated with system-level simulation solver called Architect to enable the optimization of the sensor circuit output. It involves a hybrid approach which uniquely combined FEM analysis and piezoresistive modeling using circuit simulation environment which results in optimal performance of MEMS piezoresistive microcantilever sensor.
Kinetic Analysis of UV-Curable Epoxy Resins for Micromachining Applications
Authors: Yu Voytekunas Vanda , Lin Ng Feng , Ling Koh Chai , Marc Abadie
Published: September 2009

Multifunctional epoxy resin series Epiclon HP-7200 is classified under the high performance series and is well known for its application in electrical encapsulation as it exhibits excellent mechanical and electrical properties. In addition, they have an advantage of an ultra low moisture absorption compared to other conventional cresol novolac (ECN) and biphenyl epoxy resins, which potentially makes it the next new mainstream of epoxy resins in electronics application. In this paper, kinetic study of various concentration of Epiclon HP-7200 (40-70 wt %) with divinyl ether (DVE) as the reactive solvent has been performed by Photo-Differential Scanning Calorimetry (DPC). The thermal stability of the Epiclon HP-7200 solutions has been analyzed by DSC and TGA.
S3 Micromachine as Multi-Scale Interface for BME
Authors: Konishi Satoshi
Published: September 2009

This paper describes multi-scale interface for bio and medical engineering based on MEMS technology. MEMS technology can provide various interfaces for biomedical application corresponding to hierarchical components of living organism such as cell, tissue, and organ. This paper mainly deals with small, soft, and safe (S3) micromachine as multi-scale interfaces for medical application. Micromachine is small in nature. S3 micromachine is based on its soft and flexible structure and safe driving principle. These features are suitable for advanced medical tools for minimally invasive medical operations. S3 micromachines-based medical tool has been applied to a retractor for spacing in front of the endoscope at our early stage. This paper also presents the S3 micromachine as a surgical tool for a cell sheet transplantation in an eye.
Mathematical Modeling of Hydrogels for Microfluidic Flow Control
Authors: Kurnia Jundika Candra , Birgersson Erik , Mujumdar Arun Sadashiv , Quah Lee Ching
Published: September 2009

A mathematical model of a microfluidic controller comprising a hydrogel in a typical T- and Y-junction is derived and presented. The model takes into account conservation of momentum, mass and ions for laminar incompressible flow and the deformation/sensing of a pH-sensitive hydrogel. The response of the pH-responsive hydrogel is validated with experimental equilibrium swelling curves for which good agreement is found. The model is employed to study the behavior of the hydrogel and its impact on the overall fluid flow in different microfluidic flow channel/hydrogel configurations, e.g. in a T-junction, where the hydrogel can act autonomously and without external power supply to regulate the flow. Finally, we discuss how the model can be generalized for other types of stimuli-responsive hydrogels.
In/Ex-situ Detection of HBV DNA Using Dynamic Microcantilever
Authors: Kim Tae Song
Published: September 2009

The microcantilevers have emerged as a versatile biosensor, and showed excellent performance such as high sensitivity, high selectivity, and label-free detection. They have been successfully used for the detection of nucleic acids, disease marker proteins, cells, and pathogens including small molecules. So far, our group has successfully demonstrated the marker protein detection using the actuating layer (PZT)-embedded microcantilevers for the last decade. Here, we introduce in/ex-situ monitoring of the DNA binding events using performance improved actuating layer-embedded microcantilever sensors. To obtain the stable and reliable resonant frequency shifts, the microcantilevers were passivated with parylene-C film for in-situ detection and perfluorosilane (PF-Si) film for ex-situ detection. To achieve the recognition layer, the probe DNA (37-mer including T10 spacers) specific to HBV DNA was immobilized on the gold-coated microcantilever, and followed by backfilling of ethylene glycol spacer (HSC11-EG3-OH) to increase the DNA binding efficiency. After the surface treatment, the detection of HBV DNA (27-mer) was performed through two manners, in-situ and ex-situ. Target DNA in the range of 1 to 20 M and 10 nM to 5 M were applied for the in-situ and ex-situ detection respectively, and the resonant frequency shifts according to the concentration was examined quantitatively. From the results, we explained the relationship between the DNA hybridization and the nanomechanical response. In addition, we presented a hypothesis on the different tendency of in-situ and ex-situ results.
All-Optical Signal Processing Based on Nonlinear Effects in Semiconductor Optical Amplifiers
Authors: Wu Jian , Wang Min Xue , Wu Bing Bing
Published: September 2009

In this paper, we report our recent studies on developing nonlinear techniques based on a single SOA for all-optical signal processing at high-speed, with a focus on simple configurations employing commercial SOAs for several key all-optical network applications. Our researches are based on nonlinear polarization rotation (NPR), four-wave mixing (FWM) and cross-phase modulation (XPM) effects in a single SOA. We propose and demonstrate applications of the nonlinear techniques in all-optical logic gates, multi-function format coversion, tunable Lyot birefringent filter and multi-channel optical time division multiplexed (OTDM) demultiplexing.
Analysis of Novel Building Blocks for Photonic MEMS Based on Deep 1D Photonic Crystals
Authors: Malak M. , Duport F. , Cai Hong , Saadany B. , Nicole P. , Polleux J.L. , Marty F. , Formont S. , Liu Ai Qun , Bourouina Tarik
Published: September 2009

This papers deals with the study of novel building blocks suitable for architectures of MEMS tunable lasers integrated in SOI platforms. These building blocks are based on the use of 1D photonic crystals (1D PCs) made of silicon-air thin layers stacks. These provide high reflectivity in certain wavelength range as well as access to simple Fabry-Perot cavities. The latter was studied more in detail and simulations are presented along with preliminary experimental results. A tilted Fabry-Perot cavity was analyzed for its potential of mode selector to prevent for mode hopping and thus enable continuous mode tuning by control of separation gap. As 1D PCs exhibit dispersion characteristics, this behavior is analyzed as well for its potential use for compensation purposes of wavelength dependence of the refractive index in the III-V gain medium.
Flexible Micro-Structured Mold for UV Micro-Casting of Polymeric Microdevices
Authors: Yeo L.P. , Wang L. , Wang Zhi Ping , Lam Yee Cheong
Published: September 2009

UV micro-casting is a promising mass production method for replication of polymeric microdevices due to the non-stringent process conditions and fast curing time. This paper describes a potential method to mass produce polymeric microdevices. The first generation mold for UV micro-casting was fabricated by using chemically micro-etched copper clad laminate (CCL) base substrate. Subsequently a two part silicone rubber was cast over the CCL micro-feature mold. Photosensitive resin was dispensed onto the silicone rubber mold and a transparent Mylar thin film was placed on top of the UV curable prepolymer. After the silicone rubber mold-resin-Mylar assembly was UV irradiated for tens of seconds, the crosslinked polymer, together with the Mylar film was peeled off from the mold. The cross-linked polymer was placed on top of a second layer of Mylar film dispensed with the similar UV curable resin. In this way, a complete polymeric micro device could be efficiently produced.
Mixing Enhancement of a Passive Micromixer by Applying Boundary Protrusion Structures
Authors: Hsieh Chang Yu , Yang An Shik
Published: September 2009

The purpose of this study is to examine the mixing behavior of two test fluids flowing via a passive micromixer with protruded structures arranged at the boundary of the mixer. In the analysis, the theoretical model was based on the three-dimensional conservation equations of mass, momentum and species concentration; whereas, the governing equations were numerically solved by using an iterative SIMPLEC algorithm to resolve flow/transport properties. The predicted mixing efficiency at different axial locations was compared with available measured results in the literature for code validation. Numerical experiments were extended to study the shape effect of boundary protrusion structures on mixing enhancement of a passive micromixer with diamond-shaped obstructions.
Design and Characterization of a MEMS-Microfluidic Sensor for Rheological Applications
Authors: Berthet H. , Stone H. , Marty F. , Mercier B. , Jundt J. , Angelescu D.E.
Published: September 2009

We present our efforts to design, manufacture, and characterize a capillary viscometer aimed at performing very high shear rate rheology of complex fluids, and fabricated using hybrid MEMS/microfluidic technology. We demonstrate that microfluidic and MEMS technologies can be combined to integrate fluidic channels with microfabricated stress and flow sensors, enabling rheological measurements at shear rates up to 500000s-1 and beyond.
Development of Liquid Tunable Diffractive/Refractive Hybrid Lens Based on Combination of Diamond Turning and Soft Lithography
Authors: Leung Hui Min , Yu Hong Bin , Zhou Guang Ya , Senthil Kumar A. , Chau Fook Siong
Published: September 2009

A liquid tunable diffractive/refractive hybrid lens which combines the use of high precision diamond turning and soft lithography is developed in this work. This diffractive/refractive hybrid lens comprises a Fresnel lens and a tunable refractive lens automatically aligned during the fabrication process. Multiple PDMS hybrid lens devices can be fabricated from the diamond-turned master mould and AFM results show that the surface quality of the PDMS lenses meets the requirements for optical purposes. The hybrid lens is tested with a green laser (λ = 532nm) and experimental results demonstrate a tunability of more than 20mm.
Depletion Model of Aluminum in Bond Coat for Plasma-Sprayed Thermal Barrier Coatings
Authors: Che Chang , Wu G.Q. , Qi Hong Yu , Huang Z. , Yang Xiao Guang
Published: September 2009

The aluminum depletion of NiCrAlY bond coat in an air-plasma-sprayed thermal barrier coating (TBC) has been studied by experimental and simulative approaches. Upon thermal exposure, Al depletion regions were observed. The depletion of aluminum is resulting from Al diffusion towards the surface of bond coat and into substrate. A mathematical model of Al depletion was presented. The model is able to explain the observed results in a qualitative way and has been shown that Al depletes within the bond coat by diffusion.
Oxidation Resistance of Multicomponent CrTiAlN Hard Coatings at Elevated Temperatures
Authors: Tam P.L. , Zhou Zhi Feng , Shum P.W. , Li K.Y.
Published: September 2009

Quaternary CrTiAlN hard coatings were deposited by closed field unbalanced magnetron sputtering ion plating technique onto steel substrates, and their structural, mechanical, and tribological properties after heat treatment in air at different temperatures (500-900 oC) were studied and compared by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), micro-indentation, and pin-on-disc (POD) tribometer, etc. The onset temperature of oxidation was determined by thermogravimetric analyser (TGA). The compositional depth profiles before and after the heat treatments were examined by X-ray photoelectron spectroscopy (XPS) in order to study the oxidation mechanism. The experimental results indicate that the CrTiAlN coatings have excellent oxidation resistance and thermal stability, and outperform the traditional hard coatings like TiN and TiAlN in terms of higher oxidation temperature, hardness, adhesion, and wear resistance. It is expected that the CrTiAlN coatings with superior properties should have better performance in dry high speed machining.
Development of Spherical Iron-Based Composite Powder with Carried Alumina Abrasive Grains by Plasma Spray
Authors: Hanada Kotaro , Yamaguchi Hitomi
Published: September 2009

This paper describes the development of spherical iron-based composite powder with carried alumina abrasive grains made by a plasma spray technique. Carbonyl iron powder (7.2 μm average size) and alumina abrasive grains (0.3 μm average size) are sprayed into the plasma flame from the respective nozzles simultaneously, or their mechanical mixture is directly plasma-sprayed. In case of the composite powder obtained by the direct spray method, the alumina abrasives are well carried on the carbonyl iron particles. However, a plasma current of more than 100 A causes melting and vaporizing of the alumina abrasives;, consequently the carbonyl iron and alumina abrasives are separated. The magnetic abrasive experiments with the composite powder developed are made for SUS304 stainless steel plate, and the result shows that the developed composite powder has high potential abrasive performance.
Ceramic Coatings by Electrophoretic Deposition: Processing and Properties
Authors: Baufeld Bernd , Rätzer-Scheibe Hans Joachim , Van der Biest Omer
Published: September 2009

Electrophoretic deposition (EPD) allows the fabrication of ceramic coatings at lower cost and higher speed than most other deposition techniques. The processing consists of powder deposition from a suspension under the influence of an electric field and subsequent consolidation of the coating by sintering. Adherent zirconia coatings with coating thicknesses up to 0.1 mm were obtained from different suspensions, one methyl-ethyl-ketone and the other ethanol based.
The standard sintering temperature is 1200°C, which easily may damage or change the substrate and also means high production costs. In order to reduce the sintering temperature, suspensions with the addition of ZrN were investigated. Due to reaction bonding, sintering in air at a remarkable low temperature of 1000°C was successful.
The elastic modulus of the EPD coatings has been derived from impulse excitation experiments and the thermal conductivity from laser flash analysis. The elastic modulus was about 22 GPa and the thermal conductivity between 0.4 and 0.6 W/(m•K) at room temperature, both decreasing slightly with temperature. Especially the exceptionally low thermal conductivity makes EPD coatings a promising candidate for thermal barrier coatings.
Prediction of Surface Roughness by 3D-CAD Model in Helical Scan Grinding and Groove Grinding
Authors: Iwai Manabu , Shiraishi Yoichi , Ninomiya Shinichi , Uematsu Tetsutaro , Suzuki Kiyoshi
Published: September 2009

This paper deals with prediction of improvement in surface roughness in helical scan grinding by simulation of virtual ground surface with a 3D-CAD model. It has been found that, by choosing the value of parameters of four grit conditions such as grit arrangement, protrusion height, apex angle and inclination angle randomly to a real wheel, the maximum unevenness of the virtual ground surface and tendency of its change with feed angle nearly coincide with the surface roughness in the experiment of helical scan grinding. Furthermore, it is demonstrated that this analyzing method can be applied to R-shaped groove grinding and suggested that helical scan grinding is effective in grinding bearing grooves.
Measurement of the Tangential Grinding Force Using the Slip of an Induction Motor—Construction of the Measurement System
Authors: Kondo Kazuki , Tooe Shin-Ichi
Published: September 2009

A new system for measuring a tangential grinding force using the slip of the rotational speed of an induction motor was developed. The motor slip is measured as the change in the rotational period for the induction motor. The system operates LabVIEW software on a personal computer, and a rotary encoder is connected with the motor spindle, which drives the axis of a grinding wheel. A signal of one pulse per rotation from the rotary encoder is input to the interface of the computer to measure the rotational period. LabVIEW has the flexibility of a programming language and operates within a graphic environment in compiling the signal, analyzing measurements, and displaying analysis results. Thus, the present system is simpler than previous development tools. This work conducts a grinding experiment using the developed system to verify the sensitivity and response in measuring the motor slip. As an example of application, semidry grinding is investigated by measuring tangential grinding forces. Hence, we demonstrate the effectiveness of the developed system for data processing in the analysis of grinding phenomena.
The Effect of Special Structured Electroplated CBN Wheel in Dry Grinding of 100Cr6
Authors: Rabiey Mohammad , Tawakoli Taghi , Wegener K.
Published: September 2009

In many grinding applications, the material removal rate (MRR) is constrained by undesired thermal surface damages like burns and tensile residual stresses as well as dimensional inaccuracy. In dry grinding, due to lack of coolant, the limitation to achieve higher MRR is more critical as the major part of the heat, generated on the contact zone, is transferred to the workpiece. That is why the lower heat generation is a most important target by dry grinding. This paper presents some of the very interesting results by a comparison between a structured electroplated CBN wheel and a conventional one during surface grinding of steel. One of the grinding wheels has the normal structure and the other has special macro-structure topography developed for dry grinding. The results show a considerable reduction in grinding forces and less thermal damages using the novel electroplated CBN wheel comparing to conventional wheel.
Contact Stiffness of Grinding Wheels due to the Difference of Table Feed Rate
Authors: Yamada Takazo , Lee Hwa Soo , Miura Kohichi
Published: September 2009

Usually, the contact stiffness between a grinding wheel and a workpiece has been measured in a stationary state. So, in this study, the contact stiffness under the grinding operation is measured under different table feed rate of the workpiece. From this result, it is known that, while the contact stiffness in the stationary state increases with the increase of the contact force, the contact stiffness under the grinding operation decreases with the increase of the normal grinding force relating the table feed rate. In this paper, since the number of contacting abrasive grain with workpiece is constant irrespective of the table feed rate, and the residual stock removal of workpiece is varied by the table feed rate, it is clarified that the contact stiffness under the grinding operation differs from the contact stiffness measured by the stationary state.
Vibrations Representation in Grinding Wheels’ Virtual Truing and Dressing Model
Authors: Bzymek Zbigniew M. , Duzy Glenn M. , Mindek Richard B.
Published: September 2009

The results of truing and dressing depend on: sharpness of the dresser, speed of dressing, depth of cut and vibration phenomena. Prediction of the optimum wheel surface for grinding which produces an accurate profile and cuts most efficiently can minimize the time and cost and optimize performance of the operation before it is performed in the shop. It has especially significant meaning in truing and dressing of hard CBN wheels. The research described in this paper shows computer simulated and visualized wheel surface before and after the wheel dressing process. This paper provides additional results to those was reported in [8] taking into account the influence of vibrations. It is a companion paper to [8].
Development and Application of a Micro-Honing-Tool
Authors: Chen Shun Tong , Yeh Ming Chie
Published: September 2009

The major aim of this study is to present a novel technique for honing the micro-hole. It is difficult that regarding the finish machining of the micro-hole that the diameter is less than 300 m. First, a new process that to on-line accurately fabricate the micro-honing-tool using micro-EDM, micro-co-deposition and micro-wire-EDM is proposed for honing the micro-hole. A micro rod for as the substrate of the micro-tool is formed by wire-EDM and then co-deposited with 0-2 m CBN-abrasives. Subsequently, it is axially and crisscross cut for an appropriate length by micro-wire-EDM to make the crotched microstructure. The whole processes are able to be on-line realized since all working positions are recorded in detail and fabrication technologies are offered sufficiently on the same system. As a result, per the same fabrication-system, the micro-honing process is also on-line conducted. The finished micro-honing-tool is employed directly without unloaded and reloaded. The grinding-block can compactly stick on the wall surface of the micro-hole due to the radial elasticity of the micro-tool and then fast grind away the uneven surface by removal of micro amount. Experimental results demonstrated that the circularity and surface roughness on the hole-wall is evidently improved. Comparing with the obtained machining surface by micro-EDM hole-drilling, the original surface roughness of near one-sixth time can be achieved. It is indicated that the micro-hole can be honed accurately using the proposed technique.
Effects of Vibration-Assisted Grinding on Wear Behavior of Vitrified Bond Al2O3 Wheel
Authors: Tawakoli Taghi , Westkämper Engelbert , Azarhoushang Bahman
Published: September 2009

The total removal of grinding wheel material includes two main parts. The larger of the two is the result of dressing and truing operation and the other relatively small part is due to the wheel wear which takes place during the actual grinding process. The frequency of dressing and truing operations depends on the cutting conditions, wheel characteristic, etc. However in dry grinding as there is no cutting fluid to transfer the heat from the contact zone, the wheel wear during grinding and the frequency of dressing is much higher due to the higher grinding forces and temperatures. Vibration grinding reduces wear of the grinding wheel during the process considerably and decreases the frequency of dressing operation significantly. Hence it increases the efficiency of the process and reduces the cost. The investigation carried out in the KSF institute shows the improvement on the surface roughness, reduction of the grinding forces, thermal damage of the ground surface and radial wear of the grinding wheel in case of using vibration grinding comparing to conventional grinding. The designed and developed ultrasonically vibrated workpiece holder and the experimental investigation show a decrease of up to 80% of radial wear of the grinding wheel.
A Briefing on the Manufacture of Hip Joint Prostheses
Authors: Zhang Liang Chi , Kiat E.C.S. , Pramanik Alokesh
Published: September 2009

To produce lifelong, harmless hip joint prostheses, considerable cross-disciplinary studies have been carried out. The research includes adaptability and sustainability of artificial materials to human body, selection of materials, precision fabrication and efficient replacement operation. This paper provides a brief review of some of these key aspects with some details in abrasive polishing.