In the microoptics field, precise alignment is very important to reduce the coupling losses in optical links. In this paper, a novel device of passive and fixed alignment of optical fiber is proposed. The rectangular V-groove formed by one sidewall of SU-8 resist and the substrate is used to position the optical fiber, and the leaf spring with flexure hinge clamps it. The spring is fabricated by the sacrificial layer technique. The clamping force provided by the spring acts on the upper semi-circle of the optical fiber's cross section, so that the device need not use the additional cover on the optical fiber to perform the vertical location and the final fixing. It has simple structure and process, and is convenient to assemble and integrate with other microparts. The coupling of two optical fibers using the devices in our experiment has less than 1.5dB insert loss.

We discuss grating array spectral sensors as the most promising basic architecture for future high-end micro-spectrometers. New extensions of this architecture with 2D-detector arrays are presented. They increase the spectral resolution by sub-pixel imaging. Sub-pixel architectures allow miniaturization of the spectrometers and shift the limits significantly towards the diffraction limit to the grating. To fully employ this, the slit dimensions have to be in the order of a few wavelengths, for instance down to 2 ?m in the UV region, requiring micro-machined entrance apertures. Feasible entrance apertures are transmissive MEMS, such as static slit patterns, micro shutters or mechanical slit positioning systems.

NASA’s pursuit of reducing the size, weight, and cost of satellite systems, for advanced space systems, is providing a vital thrust to the development of systems-on-a-chip. Novel smart vision systems that incorporate active pixel photo-detectors, MEMs tunable etalons, electro-optical information processors, and applications of the novel smart vision system, including remote sensing, hyperspectral imaging, biomedical imaging and adaptive optics are discussed.

We fabricated a two-dimensional subwavelength grating (SWG) on a gallium aluminum arsenide (GaAIAs) double power double hetero (DDH) junction structure. The GaAIAs DDH structure functions as a photodiode (PD). The fabricated grating had 200 nm period and the tapered grating shape with aspect ratio of 1 .38 to prevent reflection in the visible and near-infrared spectral regions. The SWG was patterned by electron beam lithography and etched by a fast atom beam (FAB) with Cl2 and SF6. The novel etching technique using the two kinds of process gas of the FAB for fabricating the tapered grating with high aspect ratio was proposed. The reflectivity was examined at wavelengths from 400 nm to 800 nm. The reflectivity of the SWG was less than 1.0% at wavelengths from 400 nm to 780 nm. For example, at wavelengths of 440 nm and 780 nm, both reflectivities of the SWG decreased to 0.02% from 45.31% and 38. 1% of the flat surface, respectively. The theoretical calculations of the reflectivity were carried out by using rigorous coupled-wave analysis. The calculated reflectivity agreed well with the measured results. The I-V characteristics of the PD were measured by using laser diode light. The open-circuit voltage, short-circuit current and total conversion efficiency were improved by fabricating the SWG.

We proposed a micro-translation-table to convey a recording medium to a near-field optical head. The microtranslation- table consisted of inverted scratch-drive-actuators (SDAs) actuated by electrostatic force. The microtranslation- table was fabricated on a silicon substrate with surface micromachining technology. The SDAs were arrayed in the same direction. An object was translated by mounting the object on the inverted SDA array. Each SDA can be operated with the step resolution of 1 nanometer order. Therefore, the SDA array is precise as well as powerful. We observed that a micro object was translated in the designed direction with the fabricated SDAs by applying AC voltage of ±600 V at 100Hz. The size of the SDA plate was 70 µm long, 70 µm wide, 1.3µm thick and with the bushing of 1 .5 µm high. We proposed a novel mechanism releasing the SDAs from the object by retracting them. Therefore, the X-Y translation is possible by placing the inverted SDAs in four different directions. When the SDA was retracted, the vertical displacement of the SDA plate was measured.

A kind of 0°-90° tilting micro-mirror with fiber holding structures monolithically, which is composed of a metal-coated polysilicon or single crystal silicon film, is fabricated by the MEMS process technology based on regular silicon wafers as well as SOl wafers using the mixed micromachining of surface and bulk silicon microelectronics. According to the scalar scattering theory, a mathematical model, which describes the effects of the surface roughness on reflectivity and scattering, is constructed to analyze the optical properties of micro-mirrors. Then the surface roughness of a series of micro-mirrors with different coated metals is measured by the AFM. The diffraction effect of etching holes and the optical power transmission through MEMS multi-layer membranes are analyzed in theory preliminarily. To characterize the dynamic response of the micro-mirrors and optimize the design of driving system, a novel reduced order model of micro-mirrors is brought forward to fulfilled the mechanics-electrics coupling simulation to verify the theoretical analysis and the experimental results easily. Based on the investigation on theory, simulation and experiments together, some ameliorated processing methods of producing the micro-mirrors are advanced to improve the total performances.

In this paper we report a simple design of a micro-optical shutter/attenuator. The standard MUMPS process was used to fabricate the device. A vertically erected, gold-coated, 200x300 ?m side length micro-mirror was precisely placed between the end faces of two closely spaced optical fibers. The position of the micro-mirror with respect to the optical fiber end face was controlled by a nano-stepping motor array. Optical and mechanical tests were performed on the device. A 1.55 ?m laser beam was sent along the optical fiber. When the micro-mirror was removed from the front of the fiber, the coupling efficiency between two fibers was –10 dBm. Once the micro-mirror was placed in the optical path the coupling efficiency dropped to –51.5 dBm. The best attenuation was obtained when the micro-mirror blocked the whole cross-section of the laser beam diameter. It is evident that the device can operate as a high precision fiber optic attenuator or shutter.

As micro electro-mechanical system (MIEMS) technology matures as an industry, the integration of standard integrated circuit and multi-MEMS-sensors will continue to increase. When assembling multi-sensors into a micro electro-mechanical system, usually exists axis-misalignment problem, which will inevitably induce large measurement error. This paper proposes an error compensation scheme based on optical alignment for solving this problem. A functional explanation is followed by a brief description of the optical layout. The computation including investigation and compensation to the axis-misalignment is covered later. Finally tests are conducted with a micro electro-mechanical azimuth-level detector to prove the validity of the method.

Some of the most important steps in manufacturing microelectromechnical systems (MEMS) are their assembly and handling. With handling we mean the way we can safely, without damages, pick microparts of any shape or any kind of material, rotate them to the desired orientation and finally position them precisely on or connect them with other microparts. For these purposes, specially designed tools – microgrippers – are required. This paper presents the design, development, fabrication method using the SU8 technology and post-fabrication processes with the goal to obtain a new type of micro-gripper. This micro-gripper was produced for a handling and assembly station developed at the IMFT (TU Wien). To investigate the obtained structures we performed a "quality inspection" and a calibration of the gripper parameters. These investigations gave an important insight on such parameters as technology accuracy, parameter settings for the SU8 technology, the obtained properties of the structure and the functional features (elasticity and applied force). Based on this, possibilities for further quality improvements have been considered.

In this paper we report the fabrication of 1.3µm Si-based MEMS tunable optical filter, by surface micromaching. Through wet etching of polyimide sacrificial layer, a tunable Fabry-Perot filter was successfully fabricated. We make the capacitance measurement of the prototype device, compare the experimental curve with the theoretical one, and explain the difference between them.

This paper explored a new micro-fabrication design of color filter for liquid crystal displa , which was based on the so-called ink-jet technology today. Technicall , a new type of micro-fluidic method was presented to realize the most important manufacturing steps of color filter that specific red, green, and blue ink droplets generated from the drop-on-demand jet heads could be accuratel deposited onto a transparent substrate. Physicall , those droplets were automatically formed very thin color films because of natural liquid surface tension between the droplets and substrate. To obtain the desired thickness of color film, high walls were made on the surface of the substrate to allow the droplets freely flow in essential one dimension under constraint of two neighboring walls before the film forming and drying. As a result, a color filter with desired striped pattern we designed could be simply completed; for example, the droplets of 60-micrometer diameter might be expected to yield a 110-micrometer by 110- micrometer pixel of color filter with color thickness of one micrometer . By comparison with current pigmentdispersed method, we estimated that similar chromatic performance in the final product could be achieved with much low cost and short manufacturing process in the presented method herein.

This article describes a mass fabrication method for integrated microlens arrays mold by using UV lithography, thermal reflow, and electroforming process. The designed microlens array can be used for back light modules to enhance panel illumination. Refractive microlens with diameter 30 and 70 ?m in array are designed in certain layout. Lithographic fabrication of photoresist cylinder is applied by using the designed microlens array patterns. Thermal reflow resulted in photoresist melting and diameter shrinkage. Due to surface tension the shape of the photoresist cylinders changes to spherical shape. The sags of microlens with diameter 30 and 70 ?m are 7.5 and 25 ?m, respectively. The cross-section profile of microlens is measured by the Taylor Hobson’s profiler. It proved that thermal reflow can produce microlens array in photoresist materials. Replication process is applied by using electroforming process. Ni-Co composite electroforming can make metallic mold with hardness Hv 500 which is close to ordinary mold materials. Sputtering silver as a seed layer is applied onto microlens array in photoresist. Electroforming can start a “build-up” process to make required microlens array mold or mold insert. Refractive microlens arrays with high dense 700 lenses per mm2 were fabricated. The surface roughness of microlens arrays is less than Ra 0.02 ?m that adapt to the conventional lens surface roughness. Since the higher accuracy and lower cost of microlens fabrication methods are needed to meet the rapid growth of micro-optical devices, the contributed fabrication techniques are essential for the industry.

The laser micro-fabrication technology for micromachine is a noticeable research direction in micro-machine manufacture. In this paper several laser micro-fabrication technologies have been introduced. They are laser mask project lithograph, focus laser beam etching, selective laser sintering rapid fabrication and laser direct deposited fused powder. Authors also introduce the micro gears made with excimer laser mask exposure lithograph in PMMA and the micro Chinese character which is as small as a tip of match made with powder laser sintering technology. Furthermore authors propose another way to make micro-part which use fiber laser or disk laser combined with nano powder.

This paper briefly introduce our work on new biochip manufacuring utilizing excimer laser micromachining. The experiment results shows, that this technology have potentials in actual microstructure forming, processing way, manufacturing cost, efficiency, etc. We investigate the projection mask ablation on PMMA, and get the microgear sample. With the relative motion between the workpiece and the mask, the repeated excimer laser pulse will etch a 3D microstructures, or even form several different profiles on the straight line microgroove. This will be very useful for the microchannel formation on Biochip.

Using pure aqueous KOH solution and a one-level mask, the reflective micromirror in the direction <100> and the fibers self-aligned V-grooves in the direction <110> were fabricated on the (100) silicon. Reflective micromirror is a part of {100} family; the surface of the mirror is perpendicular at the optical axes. The deviation brought by manual assemble can be decreased by crystal orientation self-aligned between the micromirror and fibers. Using Atomic Force Microscope (AFM), the measured the surface roughness of the reflective micromirror is below 40nm, at a wavelength of 1550nm the reflectivity ofthe micromirror was measured to be higher than 80%.

As an alternative to the visual observation method used conventionally, a new approach of sensing the displacement of suface-micromachined polysilicon actuators or microactuator arrays by the measurement of capacitance variation of the electrodes is proposed in this paper. Finite element analysis (FEA) is used to provide the relation between the lateral displacement and the capacitance. In the preliminary design, the capacitance variation is on the order of fF. In order to measure the displacement precisely, the electrode arrays are proposed. This method could be useful for testing a variety of laterally driven microactuators and arrays, including MEMDACs.

The micromachined gyroscope has the characteristics of small volume, small mass and low cost, but the high resolution can not be obtained in ordinary micromachined gyroscope, which restricts the further popularization of micromachined gyroscope. The micromachined gyroscope of electromagnetic levitated rotor (MGELR) has the working principle of conventional mechanical gyroscope and the suitability to mass-produce through micromachined technique. The micromachined gyroscope with high sensitivity is hopeful to be obtained through this way. In order to decrease the electromagnetic field coupling between different coils, the micromachined gyroscope of electromagnetic levitated rotor with new structure is brought forward in the paper. Controlling circuit is simplified in the new structure. In the paper, the working mechanism of this micromachined gyroscope is analyzed on the basis of electromagnetic field theory. Using the finite element analysis software, ANSYS5.6, the feasibility of new structure is proved. The influence of levitating coil width and its inner diameter on levitating force is concluded in the paper, and the optimum values are obtained. In the paper two types of stability coils, fork coil and arc coil, are compared, and the conclusion that the arc coil is good to the stable levitation of micro-rotor is obtained. Above all, the optimum design of levitating coil and stability coil of micromachined gyroscope of electromagnetic levitated rotor is carried out in the paper, and these provide principle for fabrication ofthis micromachined gyroscope.

Transducers, as the interface between the environment and circuits inside the systems, have been developed to be core elements of Micro-Electro-Mechanic System ( MEMS ) or microsystems. Integration of the transducer and the signal process circuit on a chip using the same technology has been the bottleneck of microsystems design. A new method of pressure-sensing microsystem has been proposed in this paper. The sensor consists of a capacitive structure fabricated by 2-layer polysilicon CMOS IC technology and a detection integrated circuit on the same chip. Front-end processing is unnecessary and only back-end processing with several photolithography steps is utilized to achieve the micromachined structure after the integrated circuit part is completed. The entire system converts absolute pressure changes, in the pressure range useful for barometric applications, from 0.5 bar to 1.5bar with the temperature between -25°C and 60°C, to frequency changes. The microsystem is designed using the standard software tools such as ANSYSTM and H-SPICE. The simulation show that the microsystem would be achieved with high performance. A sensitivity of 1Hz/4fF could be achieved.

In consequence of the trend toward miniaturization of electrical equipments and micro mechanism, the importance of nano manipulation has become recognized. A dexterous micromanipulation system with dual-arm configuration is developed for the application in assembling micro machine and manipulating MEMS parts. In the micromanipulation, the system to observe microscopic objects is important as well as a system for actual manipulating microscopic object. In this paper, a new micro-vision system is developed for the manipulation robot. The system consists of a stereoscopic microscope, two CCD cameras and an auto focus system. The positions of micro object and manipulator are measured three dimensionally by using two CCD cameras. An image data compression method is also used to accelerate the speed of image processing. With this system, the peg in hole of 0.2mm diameter task has been finished automatically.

Industry inspection is an important emerging usage of microrobots. This paper presents the design, fabrication, control and performance of an onmi-directional micro mobile robot, which is driven by three-phase electromagnetic micromotors. The microrobot has a volume of 9.5mm X 9.5mm X 9.5mm, and includes three micromotors (5mm in diameter) fabricated by micromachining and assembled manually. Two of them are used to actuate the wheels of micro robot. The other one controls the direction of wheels. In order to increase the torque and improve the rotational precision of direction micromotor, reduction gears, which have a reduction ratio of 3:1 , are assembled to change microrobot direction. And a novel closed control system of microrobot is described. The heart of drive circuit is MCU AT90S8515, which implements algorithm that allows the microrobot moves forward, backward and turns left, right or speeds up, slows down. Besides, control algorithm is designed to realize the microrobot performance. Experiments show that the microrobot can move successfully in the small spaces (15~20mm) between pipes.

The objective of this project is to develop a hovering Micro Aerial Vehicle (MAY) with MEMS microrotor technology. In this paper, we present a novel MEMS-based microrotor technology. The microrotor is only 14mm in diameter and could be used on a hovering MAy. And a special kind of MAY, a four-rotor micro rotorcraft, is described. The Reynolds number is very low in micro air vehicles, which lead to the aerodynamics of them being different from the traditional ones. In view of this, the aerodynamics of two-dimensional airfoil with very low Reynolds number is analyzed. A revised theory which combines of momentum theory and the blade element approach is applied to study the microrotor's aerodynamics. This paper also presents the design of software simulation system for hovering MAY. In particular, it is intended to estimate flight control algorithms and performance for the hovering MAY, a four-rotor micro rotorcraft. Moreover, a 3D virtual environment simulation is given as a visualization tool. Finally, we get a scheme of microrotor that is very thin, flat and trapezoidal. By using MEMS techniques, a microrotor with the theme that is only 14mm in diameter and could be drove by a 2mm electric magnetic micromotor is presented.

A MEMS based micro colloid thruster (including an source emitter array and an extractor) is designed, fabricated and tested. Source emitter array of the thruster is silicon column etched by ICP. The negative electrode on the extractor can be controlled separately. After bonding together, a single emitter and extractor works on an electrical colloid propulsion principle, and produce µN order thrust. Such a small and controllable thrust is the urgent requirement for a micro-satellite. Thrust test for the micro colloid thruster is made in high vacuum box. Thrust is acted on a cantilever beam, and the displacement of cantilever beam is detected by a current vortex sensor. Analysis to the recording data shows that the maxim thrust produced by a single emitter is about 2 µN, which is agreement with theory estimate.

This paper will focus on Au/Si eutectic bonding technology. We have set up and improved some MEMS models concerning this technique for discussion. Annealing temperature on bonding was also taken into consideration. Since hydrophilic surface has a large number of —OH groups, which can make two wafers in contact, we derive a hydrophilic surface from dipping the wafer in H2O /H202/NH4OH solution. Especially we use MEMS models with ANSYS to simulate and guide the fabrication of MEMS device. Furthermore, we have improved MEMS structure. Because its bonding temperature, voltage and pressure are low, by using the following technique we could get high density and more reliable MEMS device. We also have used this technology to fabricate gyroscope and some other MEMS devices. Classical Au/Si fusion bonding at 1000°C, and anodic at 450°C is not a commercially feasible process. We achieved AU/Si eutectic bonding technology for gyroscope and other MEMS device manufacture.

The tunneling effect is a kind of quantum effect used extensively. The sensor based on tunneling effect has some advantages, such as high sensitivity, rapid response, low power consumption, low driving voltage and so on. In particular, combined with the MEMS technology, tunneling effect has shown a good application foreground in micro sensor fields. According to the quantum mechanics, such as Schordinger's equation, the theory models of tunneling effect are presented in this paper. Also the expressions of the transmission coefficient and tunneling current about the tunneling barriers are obtained. On the basis of these, a kind of MEMS micro magnetometer based on tunneling effect is presented. The mechanics model of the membrane, which is the key component and is subjected to the axial residual stress at both ends, is founded. The membrane's parameters are optimized and simulated. Some key fabrication processes of the micro magnetometer, such as silicon wafer, glass, combined plate process are developed. Further more, the prototype ofthe MEMS micro magnetometer based on tunneling effect is fabricated.

Considering the radius difference among layers and nonlinear temperature distribution inside the fiber coil, a simple, accurate model for the quantitative analysis of the thermal induced nonreciprocity in sagnac interferometer has been put forward and confirmed by experimental results. Based on the model, a novel approach to reduce the Shupe effect by 60% has been figured out.

Precision positioning and fine motion are needed in many fields, such as micro electromechanical system, ultra-precision machine, optical alignment and integrated circuit manufacture, so it is indispensable to develop precision planar stage. A precision stage driven by one piezoactuator is made to achieve three degrees of freedom motion in plane. To realize precision positioning, movement of the stage should be detected and corresponding control scheme should be designed. A displacement detection system based on image processing is developed to measure three degrees of freedom displacement of the planar stage. The core parts of the system are CCD camera, microscope, image collection and image processing. Large rotation of the planar stage has no influence on displacement detection of the system. The system could obtain high resolution together with relatively large detection range. Performance of the planar stage is tested by the displacement detection system. Interference movements of the stage are less than the main movements. Movements of the planar stage in any direction are obtained by logical open-loop control. Micro motions detected by laser interferometer indicate the stage has very high resolution.

The scratch drive actuator (SDA) is a key element in microelectromechanical System (MEMS) technology. The actuator can be designed to travel very long distance with precise step size. Various articles describe the characteristics of scratch drive actuators.3, 6, 8 The MEMS designer needs models of SDA in order to incorporate them into their Microsystems applications. The objective of our effort is to develop models for SDA when it is in the working state. In this paper, a suspended SDA plate actuated by electrostatic force is analyzed. A mathematical model is established based on electrostatic coupled mechanical theory. Two phases have been calculated because the plate will contact the bottom surface due to the electrostatic force. One phase is named non-contact mode, and another is named contact mode. From these two models, the relationship between applied voltage and contact distance has been obtained. The geometrical model of bending plate is established to determine the relationship between contact distance and step size. Therefore we can use those two results to obtain the result of step size versus applied voltage that we expect. Finally, couple-field electro-mechanical simulation has been done by commercial software IntelliSuite. We assume that the dimension of SDA plate and bushing are fixed. All the material properties are from JDSU Cronos MUMPs. A Veeco NT1000 surface profiling tool has been used to investigate the bending of SDA plate. The results of experimental and theoretical are compared.

As a non-invasive drug delivery method, atomizing drug delivery method has become an investigating hotspot in the fields ofpharmacy and medical instruments, and has widely potential applications in the future. It is used for delivery of antibiotic, antiviral drug, anti hypertension drug, angina drug, and other drugs including peptide or protein ingredients, even bacterin and biologic synthetic. This paper proposes a piezoelectric array microjet based on MEMS, which is formed by piezoelectric transducer bonded to a silicon chip with nozzles. Droplet diameter is one of the key parameters of the microj et, and has an important effect on detailed deposit position. The processing drag, surface tension and inertia force must be overcome through continuous pressing wave produced by the piezoelectric transducer, and droplet can be squeezed out of the cavity. The theoretical problems on the characteristics of the microjet have been discussed. Conclusions are useful for the design of the microjet.

The hydrogen actuating microactuator works in the caustic electrolyte, the chemical stability of the materials is very important for the lifetime of this kind of microactuators,. As compared with mischmetal (Mm) based LaNi5 series alloy films reported before, palladium layers is more suitable for this purpose, In this paper, a prototype of electrochemical microactuator with Pd/Ni bilayer based on the hydrogen induced actuation is presented, the performance and microfabrication process of this microactuator are described in detail.

The reactive ion etching (RIE) of commercial PMMA sheet has been examined in pure 02 and CHF3/02 plasma. The aim of this study was to optimize the etching PMMA process parameter. Addition of CHF3 , which have a surface passivation effect, to Oxygen plasmas should be obtained vertical edges at an acceptable etch rate. A RIE parallel plate reactor was used and electroplated nickel film was used as mask. We discuss the influence of pure 02 and O2/CHF3 etching gas on etching profile, the influence of the etching parameters such as gas pressure and CHF3/O2 ratio on vertical etching rate, lateral etching rate and etching profile was also investigated.

The alignment of single mode optical fibres using thermally actuated cantilever platforms is investinated. These devices depend on their operation on differential thermal expansion of materials. An analysis and modeling of these thermal microactuators for fibre alignment purposes is discussed. The simulation results of microactuator deflection and the coupling losses of single mode fibres by using designed ?-Shape microactuator are presented. By setting the length of the beam to 3mm and the length of the deflecting cantilever section to 2mm, the fibre-to-fibre coupling loss is only 0.315 dB.

We report a fiber optic switch based on a novel MEMS technology allowing fast switch (<2 ms), excellent isolation (>50dB) and wide bandwidth. Each switch module consists of an electromagnetically actuated gold-coated silicon mirror rotating around a 100 µm diameter shaft and a miniature 5V driven coil. Enabling technology is precision EDM machining and laser cutting. The switch is scalable to 8 X 8 and allows the realization of high capacity cross-connects.

A micro-machined MEMS variable optical attenuator capable of greater than 40 dB dynamic range is described. The device consists of an electromagnetically actuated gold-coated silicon micro-mirror rotating around a 100 µm-diameter shaft and a miniature driven coil. Enabling technology is precision EDM machining and laser cutting. The attenuator is scalable to a discrete array to implement a WDM drop module of an add/drop multiplexer and allows the realization of high capacity cross-connects.

Using the numerical analysis method, the mechanism of the surface acoustic wave (SAW) motor is further discussed, the performances of the SAW motor under different slider and stator contact conditions are examined, and many factors that affect the efficiency of the SAW motor are introduced. In addition, the design of SAW motor with power circulation structure is illustrated. Experiments show that the efficiency of the SAW motor increases, and the threshold driving voltage of the SAW motor reduces.

This paper reports on a silicon mcrochannel arrays prepared based on bulk-micromachining technology, dry etching technology and electrochemical process respectively. In dry etching, a silicon microchannel plate (Si-MCP), with 15-30 aspect ratio of the microchannel, 6-20 µm, 6-8 µm space and 150-300µm depth, were prepared by Inductively Coupled Plasma (ICP). The phenomenon ofplasma etching lag and the morphology ofthe microchannel array in dry processing were analyzed and discussed.In wet process, both p-type and n-type silicon was selected as the substrate for microchannel arrays. A inducing pit arrays was first prepared by oxidation, lithography, KOH etching, and then a square channel arrays that has 4 µm length of side and 2 µm space were formed by electrochemical etching in hydrofluoric acid in three poles electrolyzing cell, which can yield straight holes with high aspect ratio. The electrochemical mechanism of silicon anisotropy etching, the parameters of three pole electrolyzing cell, and the inducing pit and channel morphology were investigated and discussed. The results shows that the high aspect ratio of silicon microchannel arrays can be made by both dry and wet etching processes. The ICP process yield a microchannel arrays with uneven, re-entrant, notched and ripples surface within the channel. The electrochemical process for silicon microchannel arrays has lower cost than ICP process.

The micro strain gauge with a mechanical amplifier can be in situ fabricated with active micro sensors or actuators for monitoring residual strain effects, and both tensile and compressive residual strains can be measured via the strain gauge. But the error of numerical models has not been quantitatively analyzed. The source of error is due mainly to the uncertain input values, which contain error of geometric structures and other properties. A detail error analysis to passive micro strain gauges with mechanical amplifiers, e.g. the micro-rotating-structure and other passive strain gauges, is given in this paper. And a comparison of the error of micro strain gauges is also presented so as to give a guideline for selecting the best type of microstructure.

In this paper, RF MEMS capacitive switch with a novel metal/dielectric (Au/SiN) composite beam on highly resistive silicon substrate is presented. The low-stress SiN under the Au electrode layer is adopted due to its excellent dielectric and mechanical characteristic. Four beam structures are designed, and mechanical/electrostatic and high frequency analysis tools are used to explore their performance. It can be seen from the analysis that satisfying switching property can be obtained from careful choice and optimization of the structure. Besides, the switch has shown excellent radio frequency (RF) performance. In addition, the composite beam, which is stiffer than pure metal ones, may not only provide good DC insulation and RF isolation augmentation but also theoretically help to reduce the danger of beam stiction. With different structures, this switch can meet the requirement of a wide variety ofhigh frequency applications. These features made this micro switch an optimal solution for mobile or fixed RF applications, such as in the construction of millimeter wave phase shifter MMIC and switched tunable filters, for wireless telecommunication or radar use.

System-level simulation is an important phase for shortening design cycle and reducing design costs of MEMS devices, while the key to do this is to create macromodels for the MEMS devices. An equivalent circuit macromodel for beam-structure electromechanical systems is presented in force-current (F-I) analogy. It is appropriate for small-signal time and frequency domain analysis. Comparing with the existed macormodel created by force-voltage (F-V) analogy, the F-I analogy macromodel has the following advantage: the topology of the electric network of a F-I analogy macromodel is the same one as its original mechanical network. So it is very convenient to create an equivalent circuit macromedel for a complicated MEMS in F-I analogy. Simulating results show that the F-I analogy macromodel has high accuracy.

In this paper, a new type of silicon micro-mechanical accelerometer using an optical fiber is presented. The mechanical element of the accelerometer is fabricated by an unconventional wet etching process of silicon, resulting in symmetrically suspended seismic masses with a high lateral sensitivity and very low transverse sensitivities. By forming a Fabry-Perot cavity between the seismic mass and the output of an optical fiber, the acceleration can be sensed by measuring the optical path change. The feasibility of the accelerometer is demonstrated.

This paper introduces a new test structure for thermal conductivity of poly-silicon thin films, and analyzes the feature ofthe measurement structure, modeling and measurement methods. The structure was fabricated by using surface micromachining process for vacuum encapsulation fabrication, while post- processing bulk silicon micromachining is not essential.

A bulk micromachined relay with lateral contact structure is presented in this paper. The relay is fabricated with glass/silicon wafer bonding and deep reactive ion etching (DRIE) process. it is laterally driven with electrostatic actuator. The threshold voltage of the relay is simulated using Reduced Order Modeling (ROM) methods provided by a general finite element simulator, ANSYSTM. The simulated result and experimental result are compared and discussed

Dynamic passive valve micropump is a kind of PZT actuation, valveless micropump which has higher working frequency, high reliability, simple structure, low cost. It can easily match many kinds of requirement in application. Some micropumps have been fabricated in our laboratory. The performance of dynamic passive valve micropump is in close relationship with structural parameters such as diffuser's aperture angle, diffuser's channel length, diffuser's channel smallest cross-section diameter. At the same time, its performance also depends on the fluid' s Reynolds number and the working frequency of PZT actuation as well. In this paper, firstly we give the relationship between the performance of the micropump and these parameters. Then we build a micro hydrodynamic model of micro pump by the finite element method. In this model, we take the coupling of fluid in micro chamber and two micro valves into consideration. The restriction of micro fabrication is also considered. By simulation and computation, we obtained the fluid status such as laminar flow, turbulent flow. We also get the fluid motion status such velocity of flow, the direction of the current. By some calculation, we gain the flux of micropump. Based on these results, one optimization design of micropump is attained. And according to this design, we fabricated and assembled some samples of dynamic passive micropump.

Micromechanical switches have demonstrated great potential at microwave and millimeterwave frequencies due to their very low intermodulation distortion, low power consumption, and low insertion loss characteristics. Comparing to traditional semiconductor switches, however, one of the most obstacle that hindered the application of MEMS switches is their high actuation voltage. To decrease its threshold voltage, the paper presents a novel MEMS switch. The switch is composed of a movable corrugated membrane, which can be pulled down onto the GaAs substrate at 12V. It has superior high-frequency performance with insertion loss of <0.25dB, and isolation better than 20dB at X-band frequency. Its structural design is mainly presented in this paper.

Conventional diffractive optical elements (DOEs) are usually designed to produce a predetermined function or light distribution on a single transverse plane. As we know, the unconventional light distributions are generated within a three-dimensional domain. Such as a ring-beam convertor described in this paper, the distribution with a ring profile must be consistent in any cross section. A phase-only diffractive optical element with 1 6 levels is designed for controlling the wave-front propagation within a given three-dimensional space. And it is a rotation symmetrical binary optical element that is used to convert the input uniform beam to a ring output beam. We designed this convertor by the Simulated Annealing method (SA) the iterative method based on the Block-Iterative weighted projections algorithm (BIWP) and the SA-BIWP hybrid algorithm. In this paper, we emphatically investigated and compared these three phase retrieval algorithms. The results of numerical simulation show that the procedure of the hybrid algorithm converges more stably to an optimal solution close to the global optimum with an acceptable computing time. The diffractive efficiency is higher and the energy of the output beam in the ring domain is more concentrated. Along the direction of the input beam, the intensity of the beam in each transverse plane is accordant. What's more, the hybrid algorithm is applicable to be employed to solve other discrete stochastic optimization problem ofthe design of a DOE.

A novel optical waveguide rectangular ring resonator is designed and fabricated in silicon-on-insulator (SOl). The resonator is composed of four straight waveguides connected by four 90° directional change-turning mirrors. This merged structure allows compact size and low loss. The input and output waveguides to couple energy into and out from the resonator are also designed and optimized in this work.

Microfluidics is an important technology for applications including those for chemistry/biology! medicine and those as tools for fundamental researches. Some microfluidic devices developed seemed to function as sheer miniaturized copies ofthose macro devices and most ofthem lacked sufficient cares ofthose dominant forces in micro scale, e.g. fluid-solid interactions, or only tried to avoid their influences. In fact, the active utilizes of micro scale significant forces tend naturally to be more suitable to manipulate and control flows in micro channels. In addition, the lack of the sufficient fundamental studies on micro flow phenomena and a robust and cost-effective integrating technology, making various functional devices together into a system of specific application, has been always a bottleneck problem in the development of microfluidics. In this review, we discussed some selected topics, which are of certain basic importance and concern what have been developed or are being undergone in our group. Some phenomena, which are incapable of been explained by classical Navier-Stokes theory, has been discussed and the characteristics of flows in micro systems have been described. Some examples of devices developed by our group were provided to further the discussion.