Microelectromechanical systems

An analytical study of the frequency-temperature behavior of MEMS AT-cut quartz resonator structures was performed. The piezoelectric, Lagrangian equations for the frequency-temperature behavior of quartz were employed . Two types of resonator structures were studied: A 1 GHz rectangular plate with rectangular electrodes and a 1 GHz rectangular ring electrode mesa (REM) plate. For MEMS resonators, the REM design confers certain advantages in attaining higher resonant frequencies and lower electrode noise.

In this paper, we present a novel optical microelectromechanical systems (MEMS) accelerometer sensor dedicated to space applications. An in-plane Fabry-Pérot (FP) microcavity (FPM) with two distributed Bragg reflectors (DBRs) is used to detect the acceleration. One of the DBR mirrors is attached to two suspended proof masses, allowing the FP gap to change while proof masses experience acceleration. Acceleration is then detected by measuring the spectral shift of the FPM. The optical accelerometer presented here uses silicon strip waveguides integrated with MEMS on a single silicon-on-insulator wafer, making it compact and robust. All of the device components are fabricated using one single fabrication step. Immunity to electromagnetic interference, high sensitivity and resolution capability, integrability, reliability, low cross-sensitivity, simple fabrication, and possibility of having two-and three-axis sensitivities are numerous advantages of our sensor compared to the conventional ones. The sensor performance demonstrated a 90-nm/g sensitivity and 111-μg resolution and better than 250-mg dynamic range. [2012-0098] Index Terms-Distributed Bragg reflector (DBR), Fabry-Pérot (FP), optical accelerometer, silicon-on-insulator (SOI), waveguides. M ICROELECTROMECHANICAL systems (MEMS) ca- pacitance accelerometers are currently used in spacecraft navigation systems [1], but they suffer from low SNR (which limits their sensitivity), high power consumption, temperature dependence, and high cross-sensitivity and are not immune to electromagnetic interference [2], making them unsuitable for microsatellite applications. Optical MEMS sensors are frequently used for industrial process, aerospace, and military application owing to their immunity to electromagnetic interference and possibility of operation in hazardous and high-temperature environments .

The paper presents a technique to obtain an electrically-tunable matching between the series and parallel resonant frequencies of a piezoelectric MEMS acoustic transducer to increase the effectiveness of acoustic emission/detection in voltage-mode driving and sensing. The piezoelectric MEMS transducer has been fabricated using the PiezoMUMPs technology, and it operates in a plate flexural mode exploiting a 6 mm × 6 mm doped silicon diaphragm with an aluminum nitride (AlN) piezoelectric layer deposited on top. The piezoelectric layer can be actuated by means of electrodes placed at the edges of the diaphragm above the AlN film. By applying an adjustable bias voltage Vb between two properly-connected electrodes and the doped silicon, the d31 mode in the AlN film has been exploited to electrically induce a planar static compressive or tensile stress in the diaphragm, depending on the sign of Vb, thus shifting its resonant frequency. The working principle has been first validated throug...

In this work, we will present results showing a feasibility of a MEMS microphone, based on AMS 0.35 µm CMOS standard process, with only one step of a sacrificial SiO maskless etching on the substrate front-side. The microphone design, modeling and simulated performance will be stud Fabrication of test structures obtained with a SiO shown as well as characterizations of these test structures.

In this paper we study the use of pseudorandom test techniques for linear and nonlinear devices, in particular Micro Electro Mechanical Systems (MEMS). These test techniques lead to practical Built-In-Self-Test techniques (BIST). We will first present the pseudorandom test technique for Linear Time Invariant (LTI) systems. Next, we will illustrate and evaluate the application of these techniques for weakly nonlinear, purely nonlinear and strongly nonlinear devices.

a) 1 nA、(b) 100 nA、(c) 300 nA、(d) 500 nA、(e) 700 nA、(f) 1 μA での アクティベーションを行った後の電流-電圧特性を示す。図より、設定電流の増加に伴い、絶縁的 な特性から(a)、単電子帯電効果を発現後(b), (c), (d)、非線形的な特性(e), (f)に近づいたことが確認 できる。これより、本手法を用いてナノギャップの電気的特性がアクティベーション法での設定 電流により、段階的に制御されていることがわかる。以上のことから、低温下(T = 16 K)でアクテ ィベーション法を適用することで SET の作製が可能であることが示唆された。また、設定電流 I s を詳細に検討することにより所望の特性を有する SET の作製が期待できる。

In this paper, a four hot-arm U-shape electrothermal actuator that can achieve bidirectional motion in two axes is introduced. By selectively applying voltage to different pairs of its four arms, the device can provide actuation in four directions starting from its rest position. It is shown that independent in-plane and out-of-plane motions can be obtained by tailoring the geometrical parameters of the system. The lumped model of the microactuator was developed using electro-thermal and thermo-mechanical analyses and validated using finite element simulations. The device has been fabricated using PolyMUMPs and experimental results are in good agreement with the theoretical predictions. Total in-plane deflections of 4.8 lm (2.4 lm in either direction) and upward out-of-plane deflections of 8.2 lm were achieved at 8 V of input voltage. The large achievable deflections and the higher degree-of-freedom of the proposed device compared to its counterparts, foresee its use in diverse MEMS applications.

A fiber-optic 3D confocal scanning microendoscope employing MEMS scanners for both lateral and axial scan was designed and constructed. The MEMS 3D scan engine achieved a lateral scan range of over ± 26° with a 2D MEMS scanning micromirror and a depth scan of over 400 μm with a 1D MEMS tunable microlens. The lateral resolution and axial resolution of this system were experimentally measured as 1.0 μm and 7.0 μm, respectively. 2D and 3D confocal reflectance images of micro-patterns, micro-particles, onion skins and acute rat brain tissue were obtained by this MEMS-based 3D confocal scanning microendoscope.

Design of a Power Scalable Capacitive MEMS Accelerometer Front End Colin Tse Masters of Applied Science Graduate Department of Electrical and Computer Engineering University of Toronto 2013 This thesis presents the design, implementation and fabrication for a 0.13μm interface to a capacitive MEMS accelerometer. By varying the number of amplifier slices used in concurrence based on different full scale input ranges, the analog circuitry power scales as the input range scales. Due to the oversampling nature of typical accelerometer front ends, for a full-scale input increase of N times, the analog circuitry power reduces by N times. The front end has two signal amplification stages, with the first stage power scaled. The chip is 1.15mmx1.15mm and implemented in a 0.13μm CMOS process. The design was packaged with the MEMS accelerometer chip inside a 44 pin CQFP. Measured results show an output rms noise of 63μVrms in a 100Hz bandwidth. The total analog circuitry power scales very linea...

Triboelectric nanogenerators have attracted wide attention due to their promising capabilities of scavenging the ambient environmental mechanical energy. However, efficient energy management of the generated high-voltage for practical low-voltage applications is still under investigation. Autonomous switches are key elements for improving the harvested energy per mechanical cycle, but they are complicated to implement at such voltages higher than several hundreds of volts. This paper proposes a self-sustained and automatic hysteresis plasma switch made from silicon micromachining, and implemented in a two-stage efficient conditioning circuit for powering low-voltage devices using triboelectric nanogenerators. The hysteresis of this microelectromechanical switch is controllable by topological design and the actuation of the switch combines the principles of micro-discharge and electrostatic pulling, without the need of any power-consuming control electronic circuits. The experimental...

The Planetary Imaging Concept Testbed Using a Rocket Experiment (PICTURE 36.225 UG) was designed to directly image the exozodiacal dust disk of Eridani (K2V, 3.22 pc) down to an inner radius of 1.5 AU. PICTURE carried four key enabling technologies on board a NASA sounding rocket at 4:25 MDT on October 8 th , 2011: a 0.5 m light-weight primary mirror (4.5 kg), a visible nulling coronagraph (VNC) (600-750 nm), a 32x32 element MEMS deformable mirror and a milliarcsecond-class fine pointing system. Unfortunately, due to a telemetry failure, the PICTURE mission did not achieve scientific success. Nonetheless, this flight validated the flight-worthiness of the lightweight primary and the VNC. The fine pointing system, a key requirement for future planet-imaging missions, demonstrated 5.1 mas RMS in-flight pointing stability. We describe the experiment, its subsystems and flight results. We outline the challenges we faced in developing this complex payload and our technical approaches.

This paper presents a low-actuation-voltage micro-electromechanical system (MEMS) capacitive shunt switch which has a very large bandwidth (4 GHz to 24 GHz). In this work, the isolation of MEMS switch is improved by adding two short high impedance transmission lines at the beginning and end of a coplanar waveguide (CPW). Simulating the switch demonstrates that a return loss (S11) is less than -26 dB for the entire frequency band, and perfect matching at 20 GHz in upstate position. A ramp dual pulse driver is also designed for reducing the capacitive charge injection for considering the reliability of the switch. The simulation results show that the shifting of voltage due to the capacitive charge is reduced by more than 35% of the initial value. Finally, the dynamic behavior of the MEMS switch is simulated by modal analysis and using CoventorWare to calculate the natural frequencies of the switch and its mode shapes. The switching ON and OFF time are 4.48 and 2.43 µs, respectively, with an actuation voltage of less than 15 V.

Microactuators play a vital role in several microelectromechanical systems (MEMS) that generate forces or deflections necessary to accomplish functions such as scanning, tuning, manipulation, or delivery. Utilizing a ferrite magnetic core has shown the potential to enhance the deflection of the microactuator. However, the previous study presented a complex fabrication method with high power consumption unsuitable for micropump application. Herewith, we report the impact of ferrite core length on the deflection generated by a microactuator with a simple fabrication method. The deflection behavior shows that the corresponding magnetic core length is inverse to the deflection improvement. The force reduction generated led by a longer magnetic core because of the farther distance to the coil. Our study can be used as a reference to support the development of micropump or active micromixer devices, which require compact devices with simple fabrication and high deflection, achieving ultra-high flow rate and high mixing index.

ABSTRACT: This paper presents an overview of microelectromechanical (MEMS) based oscillators. The accuracy and stability of the reference frequency will normally limit the performance of most wireless communication systems. MEMS technology is the technology of choice due to its compatibility to silicon, leading to integration with circuits and lowering power consumption. MEMS based oscillators also provide the potential of a fully integrated transceiver. The most commonly used topology for MEMS based oscillators are pierce oscillator circuit topology and TIA circuit topology. Both topologies result in very competitive output in terms of phase noise and power consumption.  They can be used for either higher or lower Rx. The major difference between both topologies is the number of transistors used. TIA circuit used more number of transistor compare to pierce circuit. Thus design complexity of the TIA is higher. Pierce circuit is simpler, provide straightforward biasing and easier to...

Tire pressure monitoring system (TPMS) plays an important role in automobile safety. One of the important components of TPMS is a MEMS pressure sensor. This paper presents the virtual prototyping of TPMS which involves design, virtual fabrication and system level modelling of a square diaphragm based capacitive pressure sensor for a given stroke length. Intellisuite® MEMS design tool is used for obtaining the virtual prototype. The analytical expression for the sensitivity of square diaphragm in small deflection regime is derived and comparison of calculated results with simulated is presented.

This paper presents the modified design of a bidirectional electrothermal chevron beam microtweezer proposed by J. K. Luo . The original design has been modified to include inward in-plane motion. Thus, the modified design is capable of bidirectional motion. The structures are designed and simulated using COMSOL Multiphysics 4.2a. The bidirectional chevron beam microtweezer shows an in-plane displacement of 2.192µm outward and 0.6178µm inward and an out-of-plane displacement of 2.1594×10 -8 m for an applied voltage of 4V. The effect of number of beams, length of beams and residual stress on the deflection of the chevron beam microtweezer has also been studied. A comparison between calculated and simulated results has been shown for the displacement of the actuator and both of them are in agreement with each other.

MEMS (Microelectromechanical system) capacitive based pure bending strain sensor is presented for use in monitoring the progress in healing of the knee after injury or after knee replacement. The sensor is designed to monitor the progress in knee bending during physiotherapy. The sensor is designed and simulated in COMSOL Multiphysics® software. The capacitive structure of sensor is composed of two parallel plates with narrow gap between them and conjoint end. The sensor is mounted on the cantilever, which responds to the strain. The dimension of sensor is very small as compared to that of cantilever beam. Therefore, its simulation is a great challenge for us. For simulation, two methods were used. First consists of only simulating the sensor by having the effect of cantilever displacement on it. Second, consists of simulating the cantilever and sensor as the two components in same model. The mechanism of sensing is based on the concept of change in capacitance due to change in gap ...

A MEMS vibration energy harvester using an Aluminium Nitride (AlN) piezoelectric layer was designed, fabricated and characterized. The harvester was fabricated on an SOI wafer with a 30μm device silicon layer which serves as the structural beam on which a 0.5μm AlN layer is sandwiched between the top and bottom electrodes. The handle silicon serves as the proof mass. The harvester has a measured resonant frequency of around 114Hz and an average output power of 54nW was measured at optimal load and a low level of acceleration (24 mili-g). A 3D finite element model of the harvester was created in COMSOL Multiphysics and the obtained results are in close agreement with the measured data.

Tire pressure monitoring system (TPMS) plays an important role in automobile safety. One of the important components of TPMS is a MEMS pressure sensor. This paper presents the virtual prototyping of TPMS which involves design, virtual fabrication and system level modelling of a square diaphragm based capacitive pressure sensor for a given stroke length. Intellisuite® MEMS design tool is used for obtaining the virtual prototype. The analytical expression for the sensitivity of square diaphragm in small deflection regime is derived and comparison of calculated results with simulated is presented.

There are a number of MEMS structures that make use of diaphragms. The deformation of the diaphragm for the purpose of actuation and transduction can be brought about by application of voltage and/or pressure or any other mechanical excitation like acceleration, force, etc. The amount of deformation can be measured by changes in the capacitance between the diaphragm and the fixed electrode. The gap between the electrodes can be an air gap or can have an intervening layer of the dielectric on the fixed electrode along with the air gap. The pull-in voltage and touch-point pressure along with the structural and material properties are critical parameters that decide the behavior of the actuator/transducer. This paper presents a simple methodology, which is capable of representing small deflection of diaphragm with pressure, and/or applied voltage. The method proposed is less complex and less time consuming in comparison with FEM tools. Closed form expressions have been derived for pull-in voltage with/without dielectric between the two electrodes and critical distance for pull-in. The closed form expressions for touch-point pressure have also been derived. The results are compared with those obtained by simulation as well as experiment.

This paper presents a study on the dynamic response of the micro-beams with the crab shape and cutout holes on the whole operating faces of the beam to create the micro-perforated beam by using FEM simulation software. The obtained results show that the size and shape form of the cutout holes affect the mechanical responses of the beam on which the holes distribute. The equivalent stiffness of perforated micro-beams decreases significantly with the increasing size of the holes on the beam operating face. And thence the major frequencies of the MEMS vibratory gyroscope system that consist of these micro-beams also decrease. The results of the study are basic for being used for optimizing the structure in subsequent research.

Miniaturization of conventional technologies has long been understood to have many benefits, like: lower cost of production, lower form factor leading to portable applications, and lower power consumption. Micro/Nano fabrication has seen tremendous research and commercial activity in the past few decades buoyed by the silicon revolution. As an offset of the same fabrication platform, the Micro-electro-mechanicalsystems (MEMS) technology was conceived to fabricate complex mechanical structures on a micro level. MEMS technology has generated considerable research interest recently, and has even led to some commercially successful applications. Almost every smart phone is now equipped with a MEMS accelerometer-gyroscope system. MEMS technology is now being used for realizing devices having biomedical applications. Such devices can be placed under a subset of MEMS called the Bio-MEMS (Biological MEMS). In this paper, a brief introduction to the Bio-MEMS technology and the current state ...

Very small electromechanical coupling coefficient in micro-electromechanical systems (MEMS) or acoustic resonators is quite of a concern for oscillator performance, specially at mmWave frequencies. This small coefficient is the manifestation of the small ratio of motional capacitance to static capacitance in the resonators. This work provides a general solution to overcome the problem of relatively high static capacitance at mmWave frequencies and presents analysis and design techniques for achieving extremely low phase noise and a very high figureof-merit (FoM) in an on-chip MEMS resonator based mmWave oscillator. The proposed analysis and techniques are validated with design and simulation of a 30 GHz oscillator with MEMS resonator having quality factor of 10,000 in 14 nm GF technology. Post layout simulation results show that it achieves a phase noise of -132 dBc/Hz and FoM of 217 dBc/Hz at offset of 1 MHz.

In radio communication, the growth of beamforming and multiple-input–multiple-output technologies, which increase transceiver complexity, have led to a drive to reduce the size, weight and power of radio components by integrating them into a single system on chip. One approach is to integrate the frequency references of acoustic microelectromechanical systems (MEMS) with complementary metal–oxide–semiconductor processes, typically through a MEMS-first or MEMS-last approach that requires process customization. Here we report unreleased acoustic resonators that are fabricated in 14 nm fin field-effect transistor technology and operate in the X-band frequency range (8–12 GHz). The devices use phononic waveguides for acoustic confinement and exploit metal–oxide–semiconductor capacitors and transistors to electromechanically drive and sense acoustic vibrations. Fifteen device variations are analysed across 30 bias points, quantifying the importance of phononic confinement on resonator pe...

Very small electromechanical coupling coefficient in micro-electromechanical systems (MEMS) or acoustic resonators is quite of a concern for oscillator performance, specially at mmWave frequencies. This small coefficient is the manifestation of the small ratio of motional capacitance to static capacitance in the resonators. This work provides a general solution to overcome the problem of relatively high static capacitance at mmWave frequencies and presents analysis and design techniques for achieving extremely low phase noise and a very high figureof-merit (FoM) in an on-chip MEMS resonator based mmWave oscillator. The proposed analysis and techniques are validated with design and simulation of a 30 GHz oscillator with MEMS resonator having quality factor of 10,000 in 14 nm GF technology. Post layout simulation results show that it achieves a phase noise of -132 dBc/Hz and FoM of 217 dBc/Hz at offset of 1 MHz.

here is currently an increased focus on the functional diversification of existing semiconductor process nodes to create new technologies 1,2 . This approach increases performance, supply chain resilience and security by reducing the number of chips from different process technologies that must be integrated and packaged into the final product. For technologies such as the fifth generation of wireless communications technology, such innovation is necessary to enable high-performance adaptable radios, where high-frequency resonators are a key element in both filters and voltage-controlled oscillators used. Recent developments in this area include thin-film bulk acoustic resonators with ferroelectric materials, as well as high-frequency Lamb-and Lamé-wave resonators using piezoelectric lithium niobate or aluminium nitride thin films 3-6 . To address band congestion, multiple-input-multiple-output arrays are becoming increasingly common as a way to multiplex transmissions between users in the same band, with large arrays allowing for increased performance across end users sharing the spectrum 7 . The beamforming enabled by such an antenna array is of particular use for higher-frequency bands, where propagation conditions are less stable due to increased radio-frequency (RF) absorption. These RF front ends require many more analogue components to be integrated in a compact form factor, driving research in RF integration into traditional digital processes. Many high-performance technologies require integration using microelectromechanical systems (MEMS)-first or MEMS-last process schemes 8-10 , which provide space and power savings compared with off-chip RF integration. The use of phononic-crystal (PnC) confinement, however, could allow resonator integration directly into a standard complementary metal-oxide-semiconductor (CMOS) process, potentially leading to larger multiple-inputmultiple-output arrays in a smaller footprint at lower power . In addition to reducing parasitics from routing high-frequency signals over long distances, this also provides the opportunity to use high-performance transistors for active transduction, leading to potentially enhanced performance. Such an approach also provides a route to future acoustic coupling between devices co-located on the same chip, which reduces the need for power-hungry phase-locked loops and allows scaled coupled oscillator systems for neuromorphic computing to be explored . In this Article, we report CMOS fin field-effect transistor (FinFET)-based resonators that utilize acoustic waveguiding confinement operating in the Institute of Electrical and Electronics Engineers (IEEE) X-band of 8-12 GHz.

This paper presents a miniaturized MEMS (microelectromechanical systems)-based electrochemical aptasensor, which utilizes aptamer as the recognition element for simple, sensitive and rapid detection of norovirus. The novelty of this work is integration of micro fabrication technology with aptamers to develop a miniaturized and portable electrochemical sensor for environmental pathogen monitoring. The binding capability between aptamers and on-chip sensing electrodes was investigated and the performance of the proposed MEMS electrochemical aptasensor was evaluated with respect to sensor response to different titers of murine norovirus, a model of human norovirus. This research forms initial basis for the development of an electrochemical MEMS-aptasensor platform and its application for virus detection.

Deposited on a flexible skin, self-made MEMS (Micro Electronically-Mechanical Systems) thermal film sensors were applied to a contoured wall surface for sensing unsteady flow behaviors. The sensors, each featuring a platinum sensing element 0.1 m in thickness on a polyimide substrate 20 m thick, were about 150-200 ohm at room temperature. The frequency response of the sensors could be up to 30 kHz when operating in constant temperature mode. In studying the unsteady flow behaviors, the flow information of interest was mainly the frequency contents of the real-time signals measured. In this paper, the three presented cases illustrate how the signals of the MEMS sensors could be used to explore the instantaneous behaviors of the unsteady flows.

Experiments were made with 14 MEMS sensors situated along the span of a circular cylinder whose aspect ratio was 5. The signals of the MEMS sensors were sampled simultaneously as flow over the cylinder at Reynolds numbers of 104. The results of Wavelet analysis of the signals indicate that the percentage of time during which strong three-dimensionality of vortex shedding was detected is about 10%.As noted, strong three-dimensionality took place when the fluctuating amplitude of the signals was severely modulated and the vortex shedding frequency reduced appeared abnormally high or low. Further noted was that the addition of a splitter plate of 0.5 or one diameter in length behind the circular cylinder was not able to suppress the three-dimensionality of the flow.

With the advancement of science and Technology an innovative mechanism is adopted to provide the assistance for physically challenged personalities. Spinal card injury persons and physically challenged persons required human assistance to move from one point to another point. Electronics interfaced Wheel chair had designed to move without any assistance. Micro Elelctro Mechanical Systems (MEMS) based accelerometer sensor is used to direct the movement of the device. The wheel chair may move forward, backward, left and right directions based on the output signal of the MEMS device. Two 'Jonson' geared motors are attached to the geared sector assembly. PIC16F72 micro controller is used to release the appropriate signals to the motor driving circuit. The developed wheel chair is best suited to meet the challenges of the physically challenges personalities.

A new fabrication process of MEMS structure prototype of a translational vibratory z-axis gyroscope sensing element is presented. This structure consists of proof mass, driving devices, sensing devices, and suspensions, using the combination of MEMS bulk and surface technology with DRIE etching techniques on the surface and a suspended structure formation using anisotropic etching on the backside of the standard SOI wafer. The mask for the fabrication process was designed using L-Edit software. With this technique, the capacitance and the mass of proof mass can be increased thus increasing the gyroscope sensitivity to sense the Coriolis force. The MEMS-based translational vibratory z-axis gyroscope was static characterized by SEM measurements, visually and resistance measurement, wiring checking, and vibration checking by a given acoustic wave gyroscope excitation.

Flexure mechanisms have immense scope in their use for applications involving high precision motion. There are many concepts to build high speed or high precision manipulators, but only a few of them can serve to obtain high speed together with high precision. Mathematical modeling of simple XY manipulator is carried out XY manipulator uses typical Double Flexural configurations. Static and dynamic analysis is carried out using MATLAB. Static analysis is carried out to determine static deflection of motion stage with force. It is observed that force deflection curve is linear. Dynamic analysis is carried out to determine frequencies and mode shapes of flexural manipulator. Further, Finite Element software ANSYS is used to carry out static and dynamic analysis of basic DFM configuration and few XY mechanisms. It is observed that close matching of FEM results with model developed.

In the paper we describe a new approach to the dielectric properties of dielectric material investigation with implementation of artificial metamaterial structure over the aperture of waveguide sensor in order to increase the sensing properties of classical waveguide sensor and to achieve the optimal design of metamaterial structure for waveguide sensor tuning in microwave X-band. In the paper the possibility to investigate metamaterial structure using for upgrading properties of classical waveguide sensor is studied, the numerical simulation of 2D metamaterial structure properties and experimental results for dielectric properties dielectric materials are carried out.

We describe recent work at NIST to develop compact, sensitive atomic magnetometers using a combination of precision optical spectroscopy, atomic physics and techniques of microelectro-mechanical systems (MEMS). These instruments have sensor head volumes in the range of a few cubic millimeters but are capable of sensing magnetic fields of a few picotesla per roothertz in the earth's field and as weak as 70 femtotesla per roothertz in a shielded, low-field environment. We discuss the design, fabrication and testing of several of these devices and propose several applications for which such instruments might be of use. I.

We describe recent work at NIST to develop compact, sensitive atomic magnetometers using a combination of precision optical spectroscopy, atomic physics and techniques of microelectro-mechanical systems (MEMS). These instruments have sensor head volumes in the range of a few cubic millimeters but are capable of sensing magnetic fields of a few picotesla per roothertz in the earth's field and as weak as 70 femtotesla per roothertz in a shielded, low-field environment. We discuss the design, fabrication and testing of several of these devices and propose several applications for which such instruments might be of use. I.

The preparation and characterisation of four-sided GaAs pyramidal mesas is presented. A novel wet-chemical etching method uses a fast lateral etching of an AlAs interlayer that influences the cross-sectional profile of the structure. The sidewalls of the prepared Ž . pyramidal structures together with the 100 bottom facet formed the cross-sectional angles 258 and 428 for mask edges parallel, Ä 4 respectively, perpendicular to the 011 cleavage planes. For mask edges turned in 458 according to the cleavage planes, 428 cross-sectional angles were obtained. Using the method, more than 10-mm-high symmetric GaAs AEgyptianB pyramids with smooth tilted Ž . facets were prepared. The quality of the pyramidal structures was checked using atomic force microscopy AFM and scanning electron Ž . microscopy SEM . Structures are suitable for the following epitaxial overgrowth of quantum structures.

A dual-channel directional digital hearing aid front end using microelectromechanical-systems microphones, and an adaptive-power analog processing signal chain are presented. The analog front end consists of a double differential amplifier-based capacitance-to-voltage conversion circuit, 40-dB variable gain amplifier (VGA) and a power-scalable continuous time sigma delta analog-to-digital converter (ADC), with 68-dB signal-to-noise ratio dissipating 67 W from a 1.2-V supply. The MEMS microphones are fabricated using a standard surface micromachining technology. The VGA and power-scalable ADC are fabricated on a 0.25-m complementary metal-oxide semciconductor TSMC process.

We have analyzed the implications of innovations in MEMS on Wireless Sensor Networks (WSN) and have modeled MEMS elements from a device prospective. We have commented on the advantages as well as the challenges that exist in this technology and described the important factors that need to be kept under consideration for the calculation of the reliability for practical implementation of MEMS based devices and the scope of modeling. We have executed the work on SUGAR of MATLAB; the proposal is then compared to the recent developments taking place and with the other experimental result which are reported. Thus a comprehensive modeling aspect of MEMS based elements of a WSN is shown. Modeling of tunable comb resonators, Vertically-shaped comb-resonators and thermal actuator has been shown and the implication of modeling in such devices has been shown. Various computations were implemented and results being given supporting the data from the experiments in recent years.

We have analyzed the effect of innovations in Nanotechnology on Wireless Sensor Networks (WSN) and have modeled Carbon Nanotube (CNT) and Micro-Electro-Mechanical Systems (MEMS) based sensor nodes. SUGAR library in MATLAB has been used to illustrate the static analysis of deflection, display the structure and to compute the displacement parameters of a cantilever beam subjected to an external force. A WSN (Wireless Sensor Network) model has been programmed using Simulink in MATLAB. We have shown the integration of CNT in WSN as CNT based sensors, microprocessors, batteries etc. A proposition is put forward by us on the changes needed in the existing sensor node structure to improve its efficiency and to facilitate and enhance the assimilation of CNT based devices in a WSN. We have shown the functioning of CNT based Nano devices in WSN technology. Finally we have commented on the challenges that exist in this technology and described the important factors that need to be kept under consideration for the calculation of the reliability of CNT based devices and their key effects on the WSN environment.

We have demonstrated the impact of developments in nanotechnology to Hard Disk Drive (HDD) technology. We have put forth a proposition to enhance the modeling of future storage devices based on innovations in the field of Nanotechnology and MEMS. We have elucidated the influence of recent advances of Nano-Composites, MEMS (Micro Electro Mechanical Systems) etc. and their implications towards the development of storage devices in the future. We have discussed about reliability modeling, nano-physics modeling and thin-film polymer modeling of HDD technology on computer-aided engineering tools such as MATLAB. We have also devised a design of Nanotechnology and MEMS enabled future HDD. We have given a small model for array based MEMS cantilevers for HDD and have used SUGAR MEMS simulation library in MATLAB to model it. We have included the parameters to be kept in mind while modeling a HDD in light of the innovations in Nanotechnology and MEMS. Finally we have stated the working of a MEMS-based actuator and presented its reliability modeling.

Powerful Computational have brought new techniques to calculate reliability by multi scale modeling supported by experimental and theoretical methods. These approaches play a crucial role in Micro Electro Mechanical Systems (MEMS) technology where the analysis is based on abstraction level theories and no comprehensive explanation of nano scale phenomenon are proposed. The Reliability modeling contains methods to calculate reliability function, failure rate function, Mean time to failure (MTTF) and Mean Residual time (MRT) are proposed for MEMS technology. It is observed that High Performance Computing (HPC) if used with multi scale optimization library then the reliability calculation and help to accelerate research in reliability of MEMS. In this developed library we can select the various physics at different level and then calculated reliability for better accuracy. It allows the user to perform simulation of a MEMS device in different environments as well as used to compute some aspects of system reliability such as Survival function and failure rate as well as multi scale modeling.

Abstract. Modern Computational methods have brought powerful techniques to calculate reliability by multi scale modeling supported by experimental and classical theoretical methods. These approaches play an im-portant role in Micro Electro Mechanical Systems (MEMS) ...