Intensive research has been going on during the past several years to use chemical and biological sensor elements to develop systems known as electronic noses and electronic tongues. They consist of several sensor elements and a pattern recognition unit comprising data acquisition and usually a neural network software. The neural network, or a similar pattern recognition tool, is necessary due to the non-linear character of the sensor system, which "learns" to interpret data during a calibration process. There are several important practical issues, such as ways to decrease the number of necessary sensors, ascertaining sufficient sensitivity, obtaining reproducibility, diminishing the need for frequent calibration, and establishing the most suitable pattern recognition technique. This paper addresses the need for multiple sensors and demonstrates that measurements of conductivity fluctuations in a sensor can lower the required number of sensors to, in principle, only one. Moreover, we shall show that a new kind of electronic nose, a sampling-and-hold electronic nose can be realized in this way.

Microelectromechanical Systems (MEMS) can be termed as a crossroad technology. Cross road in the sense that it is an amalgamation of various disciplines to produce a solution. Cross road also, in the sense that it is disruptive to the way that solutions used to be provided. At the crossroad, a decision needs to be made either to do things the old way or to embrace the new technology. In this paper, a review is made to the research and development of MEMS technology with potentially widespread applications in Singapore. In most cases, these are preparations to a possible acceleration of MEMS related industry in this part of the world. However, the author also noted that the transfer of MEMS technology from the laboratory to the industry is not a trivial matter. A major decision has to be made due to the high capital outlay and the high operational costs involved. Further, many production related issues such as yield and packaging have to be considered. A large number of MEMS commercial outfits such as Bosch are serving internal customers. As a small country with limited resources, Singapore places great emphasis on building up MEMS research and development activities to support future high value-added design and fabrication. In this paper, some of the MEMS activities in the national universities and institutes in Singapore are introduced, and some recent progress and development of MEMS technology in Singapore are presented.

MicroElectroMechanical Systems (MEMS) sensors and other micro-sensors are now readily available. This makes it possible to use modem manufacturing technologies to produce affordable and highly functional groupings (clusters) of the small and capable sensors. They beneficially share computational, communication and power resources. Printed circuit boards a few centimeters on a side, populated with the sensors and other components by fast pick-and-place machines, can form the backbone of clusters for many applications. Uses include, but are not limited to: small weather stations; systems for analysis of the atmosphere and water; monitors of fluid and power distribution systems, machinery operation, and the status of buildings, facilities and highway systems; and robots for a variety of applications, notably solar system exploration. The calibration of micro-sensors, and the reliability of such sensors and clusters containing them, are issues that require additional research. Micro-sensor clusters offer near term benefits that will not be supplanted soon by the "systems on a chip" currently under development.

Several motion detection schemes are considered and their responses to noisy signals investigated. The detection schemes include the Reichardt correlation detector, shunting inhibition neuron and the Horridge template model. These schemes are directionally selective and independent to the change in contrast. They essentially function by using spatial information and comparing it at successive time intervals. Using the detectors, the phenomenon of stochastic resonance (SR) is employed. SR is characterised by an improvement in response to a nonlinear system when noise is added to the input signal. Two types of SR are also considered, namely, subthreshold aperiodic and suprathreshold. Using stochastic resonance, the schemes are subjected to signals in an effort to improve the detectors responses with the addition of noise. We found that although added noise only further degrades the detectors response, an improvement can be gained by using some of the techniques from suprathreshold stochastic resonance.

NiICo microneedle arrays, which are fabricated by conventional near UV lithography and chemical electroplating process on a silicon wafer, are reported here. These metallic microneedles with annular structure could be easily incorporated with micropump for drug delivery and in-situ physiological fluid sampling. The mechanical strength inherent in the alloy provides excellent durability for the needles to sustain in process and clinic test.

There is much interest in the biomedical community in mechanically steering both high frequency ultrasound transducers and various optical beams. We are currently investigating the use of two different types of MEMS actuators, integrated force arrays (IFAs) and spiral wound transducers (SWTs). The IFA is a linear actuator that is a parallel network of hundreds of thousands of flexible capacitors that electrostatically contract, and the SWT is a patterned tape that is wound to form a circular network of flexible capacitors that can be electrostatically compressed to tilt desired structures. Using ANSYS finite element analysis, we have developed tilting polyimide support structures, which are fabricated on silicon wafers. High frequency ultrasound transducers (20-30 MHz) have been built on these structures and IFAs used to tilt them to steer the ultrasound beam in fluids. Prototype structures have produced 20 degree sector scans scanning at frequencies up to 30 Hz. IFAs have also been used along with similar support structures to steer optical laser beams up to 45 degrees at frequencies up to 60 Hz. The SWT is a more recent development that operates with much greater force than the IFA that could steer ultrasound and optical beams for similar applications.

Miniaturization of chemical and/or biological analytical systems requires an innovative design and new manufacturing methods. This includes the fabrication of components or structures, the assembly of these parts, and a testing strategy. The separation of an entire device into a disposable microfluidic system and a multi-use supply unit and housing allows an easy fabrication as well as low cost of operation. A simple, replicated, micro-sized, and disposable unit guarantees the same initial conditions for every analytic cycle, whereas, on the other hand all microfluidic actuators and other key elements can remain outside of the microsystem. In order to drive the implemented passive elements of the microfluidic system by external forces of the base unit, elasticity is a crucial material property. Thus silicone was used as material for the microsystem. A microfluidic system intended for use in DNA analysis employing the principles of the polymerase chain reaction (PCR) is presented. All functional units have been integrated into a complex module using a CAD-program. The 3D-drawing was converted into several machining layers for a direct laser writing CNC-code. A focussed excimer laser beam was used in order to micromachine the negative channel and reservoir system in a polycarbonate slab employing ablative photo-decomposition. Excimer laser micromachining proofed to be an ideal prototyping technique for this purpose with sufficient lateral and depth control. Its rather low throughput was bypassed with an additional hot embossed intermediate positive polyethylene master which, in turn, replicated produces the negative fluidic system in the target material PDMS (polydimethylsiloxane) as an elastomeric material. The components of the fluidic systems have been sealed with flat slabs or other microsystem parts of either PDMS or glass. In either case both parts were exposed to a plasma discharge for some seconds in order to clean, oxidize and activate the surface. This enabled an irreversible seal when two oxidized

Future smart-systems promise many benefits for biomedical diagnostics. The ideal is for simple portable systems that display and interpret information from smart integrated probes or MEMS-based devices. In this paper, we will discuss a step towards this vision with a heart bio-monitor case study. An electronic stethoscope is used to record heart sounds and the problem of extracting noise from the signal is addressed via the use of wavelets and averaging. In our example of heartbeat analysis, phonocardiograms (PCGs) have many advantages in that they may be replayed and analysed for spectral and frequency information. Many sources of noise may pollute a PCG including foetal breath sounds if the subject is pregnant, lung and breath sounds, environmental noise and noise from contact between the recording device and the skin. Wavelets can be employed to denoise the PCG. The signal is decomposed by a discrete wavelet transform. Due to the efficient decomposition of heart signals, their wavelet coefficients tend to be much larger than those due to noise. Thus, coefficients below a certain level are regarded as noise and are thresholded out. The signal can then be reconstructed without significant loss of information in the signal. The questions that this study attempts to answer are which wavelet families, levels of decomposition, and thresholding techniques best remove the noise in a PCG. The use of averaging in combination with wavelet denoising is also addressed. Possible applications of the Hilbert Transform to heart sound analysis are discussed.

Recently, several mechanisms have been proposed as a basis for designing molecular electronic logic switching elements. Many two terminal molecular devices functioning as diodes have been synthesized with responses similar to silicon devices such as rectifying and resonant tunneling diodes. In this paper, the feasibility of integrating these molecular diodes into current circuit architectures is explored. A series of logic gates and a memory element are simulated based on the voltage-controlled current flow method using the Tour-Reed molecular diode exhibiting negative differential resistance (NDR). HSPICE simulation results are used to illustrate the performance of these devices and to quantify additional component and interconnect requirements. Finally, future system design approaches using molecular components are discussed.

The computer industry has followed Moore's Law closely and faithfully over the past few decades. However, transistors cannot continue to shrink at their current rate forever, and new methods of computation must be explored. Quantum computation is one such method that has received much attention over the past few years and will heavily rely on technological advances in the smart electronics and nanotechnology arena. In this review, we will present some of the problems facing classical computers and why quantum computers may be a viable alternative. We will briefly describe some of the "killer" quantum applications, such as Deutsch's, Shor's and Grover's algorithms that demonstrate the computational powers of quantum computation. Kane's solid state quantum computer in silicon promises to demonstrate some of these applications. However there remain many significant technological difficulties which will need to be overcome if we are to see a useful quantum computer. The main technological challenges, for Kane's solid-state computer, of interest to the smart materials and structures community, will be highlighted.

A study of pressure-driven liquid flow in microchannels is presented with the aim of providing a simple model for microfluidics. The paper presents the initial research effort, which covers a survey of CFD packages, the general principles for fluid dynamics, and a simple model of flow in microchannels formulated from these governing equations. The model demonstrates how the capillary force affects the flow and the applicability of boundary layer theory to the flow in a microchannel. The simulation of textures in a microchannel, and difficulties in modelling, are then discussed.

The use of ultrasonic technologies to trap and filter desired particulates from a suspending media has been well documented to date. Recent advancements in microsystems and micro-fluidic technology have enabled the design of a miniaturised ultrasonic particle separation unit. The automated microsystem enables contact-less microprocessing operations to be conducted on small volumes of fluid suspensions in remote environments. Furthermore, the protocol for particle separation is simplified and reduces the need for operator handling. The microfabricated ultrasonic separator sub-system is combined with micro-fluidic components (valves, pumps, flow sensors) manifold systems and surface mount interface electronics to monitor and control the system's function. The operational function of the system utilises two reservoirs; (i) a pre-process reservoir containing crude sample extract, and (ii) a second reservoir holding wash media. During operation, a crude sample is channelled into the membrane-less filter system and manipulated by ultrasonic sound waves. Wash media is subsequently pumped into the filter, replacing or diluting the support media of the original sample. The sample is then removed, when desired, into a post-processing reservoir. The system has been developed for space micro-gravity operations and other configurations are applicable to other terrestrial processing applications.

A simple technique is described for the formation of microfluidic channels and reservoirs in polymer substrates. The technique is based upon excimer laser mask projection and includes a simple, low cost lift-off procedure, using readily available adhesively backed tapes, for the production of a metallisation layer. An additional advantage of the lift-off technique described is the removal of the debris layer usually associated with excimer laser ablation. The cross sectional profile and texture of the channels have also been controlled. For the electrokinetic flow device presented here, up to six reservoir structures, including electrode pads, were ablated into polycarbonate, through a sacrificial layer. The entire substrate was then coated with Cu or Au by sputter deposition. Channels, 135μm wide and 135μm deep were engraved into the samples, joining the reservoirs with a selection of "T", "Y" and "X" junctions. The sacrificial layer was then peeled off of the substrate removing both the unwanted metallisation and debris deposited during the ablation process. The channels of the devices were then sealed using a dry film photoresist material which was applied by a simple lamination process. Water was flowed through devices fabricated in this manner by pumping with a syringe and no leakage was observed.

This paper discusses the need for micromachined components in very high frequency (terahertz) electronic circuits. It is shown that, with the use of micromachining, conventional rectangular rectangular technology can be scaled down to the dimensions required for these high frequency circuits. Furthermore, the fabrication techniques are capable of producing the high quality surface necessary for low loss components. Fabrication processes are presented together with the results of electrical characterisation.

For applications at submillimetre wavelengths, an increasing emphasis is being made on more integrated front-end circuits, in which semiconductor devices plus components of the embedding structures in which they are mounted are formed as part of the same fabrication process. The work reported here concerns the development of micromachined Schottky barrier diode devices, photolithographically formed waveguide cavities and their potential for integration. Micromachined millimetre wave rectangular waveguide components have been fabricated in the negative epoxy based photoresist SU-8. Inductive iris and E-plane septa band-pass filters (centre frequency 135GHz) with respective bandwidths of 5% and 10% were formed using this low-cost method. Using dual layer SU8 processing, accurate positioning of all micromachined waveguide components within standard two-port and three-port RF test fixtures was achieved. A 6dB branch-line coupler operating at 220GHz has also been realised and similar techniques are currently being applied to micromachined rectangular waveguide tuning structures. The methods employed are suitable for sub-millimetre wave application and waveguide components operating at frequencies approaching 1THz have been fabricated.

Pulsed terahertz (T-ray) imaging systems represent an extremely promising method of obtaining sub-millimetre spectroscopic measurements for a wide range of applications. This paper investigates a number of techniques for optimally processing terahertz data. Specifically we consider wavelet de-noising and Wiener deconvolution algorithms. A goal of this research is the design and implementation of a high speed, compact and portable T-ray imaging system. This system will draw heavily on MOEMS technology. A significant challenge in the development of such a system is the development of efficient software algorithms to perform signal recognition and imaging operations in real time. This paper takes the example application of a smart bio-sensor for surface tumours and investigates the signal processing techniques amenable to the tasks of efficiently de-convolving the system response, de-noising and extracting the salient features from the terahertz response waveform.

The work described here uses microfabrication methods to integrate semiconductor devices with micromachined waveguide cavities to form submillimetre-wave frequency multipliers. Processing schemes involve both planar and three-dimensional lithography, using conventional photoresist and epoxy based SU8. Two approaches have been used. In the first, micromachining methods were employed to fabricate an integrated 270-810GHz frequency tripler. This includes a varactor diode contacted via an electroplated whisker, which is integrated with a stripline filter and waveguide probe. In the second approach, a specially designed Schottky diode chip incorporating the stripline filter/bias circuit is mounted in a micromachined, waveguide circuit block to form a 135-270GHz frequency doubler.

Multi-beam approaches using beam-forming antenna array architectures have been identified as one solution for overcoming the limited fields-of-view provided by highly directional mm-wave sensors. Rotman lenses offer a compact, rugged and reliable alternative to electronically scanned antenna technologies but architectures that operate at frequencies > 20 GHz perform poorly at higher frequencies on account of greater losses and dispersion. This paper outlines the design process for providing Rotman-based lenses, examining various levels of simulation that are needed for designs that function at K and W-band frequencies. The impact of using mictrostrip structures is demonstrated.

Excimer laser micromachining has emerged as an important manufacturing process for microsized mechanical and optical components. Using the projection mask technique this work presents and evaluates two new mask types capable of fabricating a variety of microstructures. The first new mask type is a combination of contour and gray scale mask made of chromium on quartz leading to an improved surface quality of the scanned polymer surface. The second new mask type is entirely made of quartz and makes use of tailored diffractive gratings which deflect parts of the originally illuminating laser beam beyond the solid angle of the used imaging system. This new type of gray scale mask has been applied in static laser ablation of polycarbonate fabricating 49 separate depth levels.

This paper presents the results of our investigations on the laser micromachining of structures in a dry film photoresist polymer (Dynachem, Laminar AX dry film) laminated on a copper clad Printed Circuit Board (PCB) and (100) Silicon wafer coated with Ti (15nm)/Cu (100 to 4000 nm) and copper seed layers. This study concentrated on investigating and comparing the effect of laser fluence (0.01 to 2 J/cm2) and number of shots (1 to 1000) on the etch characteristics of the Laminar AX dry film on both substrates. The other important aspects that were studied include the minimum required seed layer thickness for electroplating. The removal of the residual polymer layer at the end of the laser micromachining process and its effect on plating characteristics has been studied. The surface quality and roughness of the laser micromachined sites and their effect on the plated Nickel structures were studied in detail. The laser fluence and the number of shots used at this stage affected the conditions of the seed layer, which in turn influenced the plated film growth kinetics. The seed layers with thicknesses less than or equal to 0.8 mm were completely removed when high fluence (> around 1 J/cm2) was used. The seed layer surface after micromachining was characterised using Scanning Electron Microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and profilometer. High Aspect Ratio Structures (HARS) of Nickel were fabricated using the Laminar AX moulds. The highest aspect ratio achieved so far in this work is 6. The characteristics of these structures are discussed in detail.

This paper presents the results of our investigations on the laser micromachining of structures in a dry film photoresist polymer (Dynachem, Laminar AX dry film) laminated on a copper clad Printed Circuit Board (PCB) and (100) Silicon wafer coated with Ti (15nm)/Cu (100 to 4000 nm) and copper seed layers. This study concentrated on investigating and comparing the effect of laser fluence (0.01 to 2 J/cm2) and number of shots (1 to 1000) on the etch characteristics of the Laminar AX dry film on both substrates. The other important aspects that were studied include the minimum required seed layer thickness for electroplating.The removal of the residual polymer layer at the end of the laser micromachining process and its effect on plating characteristics has been studied. The surface quality and roughness of the laser micromachined sites and their effect on the plated Nickel structures have also been investigated. The laser fluence and the number of shots used at this stage affected the conditions of the seed layer, which in turn influenced the plated film growth kinetics. The seed layers with thicknesses less than or equal to 0.8 µm were completely removed when high fluence (< around 1 J/cm2) was used. The seed layer surface after micromachining was characterised using Scanning Electron Microscopy (SEM), Xray photoelectron spectroscopy (XPS) and profilometer. High Aspect Ratio Structures (HARS) of Nickel were fabricated using the Laminar AX moulds. The highest aspect ratio achieved so far in this work is 6. The characteristics of these structures are discussed in detail.

The problem addressed in this paper is the through-life, non-destructive monitoring of corrosion and disbonding damages in airframes. The concept presented here is to produce a MEMS smart sensor consisting of a number of small, independent, wireless sensors within the structure of the aircraft. The MEMS smart sensor can be installed during repair and in particular when the specific platform goes through a complete tear down during the Life Extension Program (LEP). The sensors are permanently installed and can be permanently monitored and contain bond degradation sensing elements and CMOS circuits. Each sensor has an independent address and can perform measurements and communicate over a true 2-wire bus to an external interface unit. US ( 09/501,798) and international (PCT/US00/03308) patent applications have been lodged for this technology.

This paper reports on the effect of using an analog feedback technique and electrode rotation on the Localized Electrochemical Deposition (LECD) process to enhance the spatial resolution and dimensional control during the growth of nickel micro-columns. Results shown here present the capability of the process for the fabrication of microstructures with high spatial resolution. Experiments were conducted on a specially assembled apparatus where nickel structures were electrodeposited onto Cu cathodes from a nickel sulfamate plating solution, using a non-soluble anode electrode. In the first part of our work, growth of the columns was found to be zero, partial or complete depending on the vertical traverse speed of the microelectrode away from the horizontal copper surface. In this case, dimensional control was limited. Efforts to overcome the said limitation in the second part achieved a constant growth rate with an analog closed-loop feedback control of the process. This improved technique produced columns with more even and controlled dimensions, therefore allowing for better spatial resolution of the structures. This was followed by deposition with electrode rotation, which produced columns with annulus cross-sections, indicating the existence of a uniform hollow core in the columns. This feature and dimensional control in the growth of the columns were not observed when using a stationary electrode - a novel development in the area of LECD and a possibility of fabricating micro-pipes for micro drug-delivery systems.

Process variations, incurred during the fabrication stage of MEMS structures, may lead to substantially different performance than the nominal one. This is mainly due to the small variation of the geometry of the structure with respect to the ideal design. In this paper we propose an approach to estimate performance variations for general planar suspended MEMS structure for low frequency applications. This approach is based on two complementary techniques, one probabilistic and the other deterministic. The former technique, based on the Monte-Carlo method, defines a random distribution on the geometric variables and evaluates the possible outcome performance by sampling that distribution. The latter technique, based on robust optimization and semidefinite programming (SDP) approximations \cite{EOL:98}, finds bounds on performance parameters given the bounds on the geometric variables, i.e. it considers the worst case scenario. Both techniques have been integrated with SUGAR, a simulation tool for MEMS devices available to the public \cite{Zhou98} \cite{Sito}, and tested on different types of folded springs.

This paper describes the analysis, design, construction and testing of two electrostatic wobble micromotors; a conventional cylindrical design and a new conical design. Both designs have stators with eight segments. The cylindrical micromotor rotor is about 4mm in diameter and 20mm long while the conical rotor has a maximum diameter of about 10mm and is 12mm long. The advantage of the new conical design is that it eliminates the need for a pivot and hence substantially reduces the size of the motor. A detailed theoretical analysis of the designs is shown and compared with experimental results. The micromotors are operated under open-loop control and the rotation of the rotor was tested at an applied voltage of up to 500V.

The Huber effect is an interesting and potential useful means for creating extremely small and simple motors. It is based on the observation that torque is produced when current is passed through a rotating ball bearing. This paper reviews the alternative explanations for its operation and describes the design, construction and characterization of two prototype ball-bearing motors based on high precision miniature ball bearings. A key limitation of earlier work has been difficulties in repeatability due to rapid wear of the motor. This was overcome by using a data acquisition system to record the dynamic acceleration characteristics and hence predict acceleration torque versus speed characteristics.

A Brownian Ratchet is a device that can rectify the random Brownian motion of particles to yield a directed steady-state flow. We can imagine a thermo-fluid field of particles which interact with the ratchet. The laws of thermodynamics imply that the ratchet must use energy from some other source. The dynamics of continuous-time Brownian ratchets are determined by a stochastic partial differential equation. We have used a simplified discrete-time model of a Brownian ratchet called ``Parrondo's games'' which are governed by a difference equation. In their original form, Parrondo's games are a finite set of simple games of chance. An indefinite pure sequence of any single game is neutral or even losing. A periodic or randomised sequence of mixed games can be winning. There is a steady state flow of probability in the preferred direction. We have been able to design a feasible and consistent device, by mapping the conservation law of total probability onto the law of conservation of charge. This device can absorb energy from a mechanical field to produce a directed flow of charge. The fundamental architecture is based on a ``bucket-brigade'' device. The capacitors are 2-port MEMS devices. We use CMOS transmission gates to connect the capacitors in the required topology. We present an analysis and simulation of the MEMS Brownian ratchet and suggest some possible applications.

Piezoelectric actuators and ultrasonic motors have advanced enormously since their beginnings over 25 years ago. They offer advantages of low speed, low inertia and high torque operation without the need for gearboxes. They are now successfully competing with conventional electromagnetic motors in applications requiring small positioning motors. Ultrasonic stepper motors and piezoactuators have not competitors in the field of ultraprecision positioning drives. Ultrasonic motors convert high frequency vibrations of a structure excited by piezoelectric elements into rotor or slider motion by a frictional drive. This principle has been configured into many embodiments, giving rapid response times, holding torque without power applied and potentially silent motion. Their miniaturization for use in MEMS (microelectromechanical systems), microrobotics and the watch industry is particularly exciting, since they have a simple construction and excellent performance for their size. Ultrasonic motors have the potential to meet space research needs as actuators for telerobotics applications. The current difficulties in designing high performance ultrasonic motors are associated with the lack of complete models and general design rules, especially in the analysis of the frictional drive between the rotor and stator. The technical problems associated with required tolerances in construction, bonding piezoelectric materials to a stator structure and the performance of different friction layer materials are not completely solved. This work discusses the state-of -the-art ultrasonic miniature motor's research, commercial application and future trends.

The main result of this paper is the development of a systematic paper-and-pencil design methodology for implementing Boolean functions of up to 4 variables using threshold logic (TL) gates, which does not require linear programming, for the first time. The method is similar in operation to the Karnaugh map logic minimization technique, and is based on determining the minimum threshold cover of a Boolean function. The paper also reviews aspects of TL and discusses aspects of the proposed design methodology when combined with the implementation issues present in neuron-MOS based TL gates. Two circuit design examples using the proposed technique are given.

Differential architectures for both first order error diffusion and also first order sigm-delta modulators are presented in this paper. Techniques required to transform single-ended architectures to differential architectures are discussed which are suitable for implementation in both PIN and NIN SEED technologies. Descriptions of common SEED circuit modules, together with SPICE behavioural simulations are also presented. A feature of the architectures presented is that they can be fully integrated into a single substrate using MEMS technologies. This can be done by incorporating integrated optical waveguides together with MMIC technology. The goal of this work is a fully integrated differential optical oversampling modulator with extremely high resolution and linearity.

During the STM-based surface modification process, the phenomena of tip-sample interaction in the case of sample bias voltage were studied in the paper. It's found that the high local current density in the tip-to-sample spacing can raise the temperature in a very small volume near the surface of sample. The local high temperature environment resulted to local melting of SiO2 glass substrate with Cr film coating. During the modification process, the Si tip oscillated with large amplitude and inserted into the glass substrate due to attractive capillary force of molten liquid. The surface can be modified and a Cr-rich hillock formed in the scanning process. A jump-to-contact mechanism can be applied to explain the surface modification process. In some special conditions, the Si tip can be bonded with glass substrate in the area on micrometer scale. The bonding strength is high. The micro-bonding technique can be applied for assembly and repair of complicated MEMS.

This work reports the tunneling effects of the lateral field emitters. Tunneling effect is applicable to the VMFS(vacuum magnetic field sensors). VMFS uses the fact that the trajectory of the emitted electrons are curved by the magnetic field due to Lorentz force. Poly-silicon cantilevers were used as field emitters and anode materials. Thickness of the emitter and the anode were 2μm, respectively. PSG(phospho-silicate-glass) was used as a sacrificial layer and it was etched by HF. Cantilevers were doped with POCl3(1020cm3). 2μm-thick cantilevers were fabricated onto PSG(2μm-thick). Sublimation drying method was used at releasing step to avoid stiction. Then, the device was vacuum sealed. Device was fixed to a sodalime-glass#1 with silver paste and it was wire bonded. Glass#1 has a predefined hole and a sputtered silicon-film at backside. The front-side of the device was sealed with a sodalime-glass#2 using the glass frit. After getter insertion via the hole, backside of the glass#1 was sealed electrostatically with a sodalime-glass#3 at 10-6 torr. After sealing, getter was activated. Sealing was successful to operate the tunneling device. The packaged VMFS showed reduced emission current compared with the chamber test prior to sealing. The emission currents were changed when the magnetic field was induced. A VMFS of angular anodes were tested and its sensitivity was about 3%.

In this paper, we consider the novel concept of a Radio Frequency (RF) controllable microvalve for different medical applications. Wireless communication via a Surface Acoustic Wave Identification-mark (SAW ID-tag) is used to control, drive and locate the microvalve inside the human body. The energy required for these functions is provided by RF pulses, which are transmitted to the valve and back by a reader/transmitter system outside of the body. These RF bursts are converted into Surface Acoustic Waves (SAWs), which propagate along the piezoelectric actuator material of the microvalve. These waves cause deflections, which are employed to open and close the microvalve. We identified five important areas of application of the microvalve in biomedicine: 1) fertility control; 2) artificial venous valves; 3) flow cytometry; 4) drug delivery and 5) DNA mapping.

We have developed a process for fabricating reproducible nanostructured silicon materials at low temperatures (<100C) using high density plasma chemical vapor deposition. These films have a column/void network morphology and they can be deposited on glass, on plastics, on metal foils, or even on substrates with previously existing, completed structures or circuits. The films have absorption properties that qualify them for the description " molecular VelcroTM In addition their optical properties can be tailored and they can have very low reflectance with high absorption in the UV. These films can easily be chemically modified and functionalized. In this report we discuss the deposition and morphology of these films. We also outline several bio-medical applications: substrates for cell growth, substrates for mass analysis for proteomics, and sacrificial layer applications for nano-and micro-channel and reaction chamber formation.