Iris segmentation

The quality of eye image data become degraded particularly when the image is taken in the non-cooperative acquisition environment such as under visible wavelength illumination. Consequently, this environmental condition may lead to noisy eye images, incorrect localization of limbic and pupillary boundaries and eventually degrade the performance of iris recognition system. Hence, this study has compared several segmentation methods to address the abovementioned issues. The results show that Circular Hough transform method is the best segmentation method with the best overall accuracy, error rate and decidability index that more tolerant to ‘noise’ such as reflection

Design and Fabrication of 3D Electrostatic Energy Harvester

This paper discusses the design of an electrostatic generator, power supply component of the self-powered microsystem, which is able to provide enough energy to power smart sensor chains or if necessary also other electronic monitoring devices. One of the requirements for this analyzer is the mobility, so designing the power supply expects use of an alternative way of getting electricity to power the device, rather than rely on periodic supply of external energy in the form of charging batteries, etc. In this case the most suitable method to use is so-called energy harvesting – a way how to gather energy. This uses the principle of non-electric conversion of energy into electrical energy in the form of converters. The present study describes the topology design of such structures of electrostatic generator. Structure is designed and modeled as a three-dimensional silicon based MEMS. Innovative approach involving the achievement of very low resonant frequency of the structure, while the minimum area of the chip, the ability to work in all 3 axes of coordinate system and ability to be tuned to reach desired parameters proves promising directions of possible further development of this issue. The work includes simulation of electro-mechanical and electrical properties of the structure, description of its behavior in different operating modes and phases of activity. Simulation results were compared with measured values of the produced prototype chip. These results can suggest possible modifications to the proposed structure for further optimization and application environment adaptation

Analytical Modeling of a New Compliant Microsystem for Atherectomy Operations

This work offers a new alternative tool for atherectomy operations, with the purpose of minimizing the risks for the patients and maximizing the number of clinical cases for which the system can be used, thanks to the possibility of scaling its size down to lumen reduced to a few tenths of mm. The development of this microsystem has presented a certain theoretical work during the kinematic synthesis and the design stages. In the first stage a new multi-loop mechanism with a Stephenson’s kinematic chain (KC) was found and then adopted as the so-called pseudo-rigid body mechanism (PRBM). Analytical modeling was necessary to verify the synthesis requirements. In the second stage, the joint replacement method was applied to the PRBM to obtain a corresponding and equivalent compliant mechanism with lumped compliance. The latter presents two loops and six elastic joints and so the evaluation of the microsystem mechanical advantage (MA) had to be calculated by taking into account the accumulation of elastic energy in the elastic joints. Hence, a new closed form expression of the microsystem MA was found with a method that presents some new aspects in the approach. The results obtained with Finite Element Analysis (FEA) were compared to those obtained with the analytical model. Finally, it is worth noting that a microsystem prototype can be fabricated by using MEMS Technology classical methods, while the microsystem packaging could be a further development for the present investigation

Role of the electro-thermo-mechanical multiple coupling on the operation of RF microswitch

A phenomenological approach is proposed to identify some effects occurring within the structure of the microswitch conceived for radio frequency application. This microsystem is operated via a nonlinear electromechanical action imposed by the applied voltage. Unfortunately, it can be affected by residual stress, due to the microfabrication process, therefore axial and flexural behaviors are strongly coupled. This coupling increases the actuation voltage required to achieve the so-called ‘‘pull-in'' condition. Moreover, temperature may strongly affect strain and stress distributions, respectively. Environmental temperature, internal dissipation of material, thermo-elastic and Joule effects play different roles on the microswitch flexural isplacement. Sometimes buckling phenomenon evenly occurs. Literature show that all those issues make difficult an effective computation of ‘‘pull-in'' and ‘‘pull-out'' voltages for evenly distinguishing the origin of some failures detected in operation. Analysis, numerical methods and experiments are applied to an industrial test case to investigate step by step the RF-microswitch operation. Multiple electro-hermomechanical coupling is first modeled to have a preliminary and comprehensive description of the microswitch behavior and of its reliability. ‘‘Pull-in'' and ‘‘pull-out'' tests are then performed to validate the proposed models and to find suitable criteria to design the RF-MEM

MISAT: Designing a Series of Powerful Small Satellites Based upon Micro Systems Technology

MISAT is a research and development cluster which will create a small satellite platform based on Micro Systems Technology (MST) aiming at innovative space as well as terrestrial applications. MISAT is part of the Dutch MicroNed program which has established a microsystems infrastructure to fully exploit the MST knowledge chain involving public and industrial partners alike. The cluster covers MST-related developments for the spacecraft bus and payload, as well as the satellite architecture. Particular emphasis is given to distributed systems in space to fully exploit the potential of miniaturization for future mission concepts. Examples of current developments are wireless sensor and actuator networks with plug and play characteristics, autonomous digital Sun sensors, re-configurable radio front ends with minimum power consumption, or micro-machined electrostatic accelerometer and gradiometer system for scientific research in fundamental physics as well as geophysics. As a result of MISAT, a first nano-satellite will be launched in 2007 to demonstrate the next generation of Sun sensors, power subsystems and satellite architecture technology. Rapid access to in-orbit technology demonstration and verification will be provided by a series of small satellites. This will include a formation flying mission, which will increasingly rely on MISAT technology to improve functionality and reduce size, mass and power for advanced technology demonstration and novel scientific applications.

An Optical Density Detection Platform with Integrated Microfluidics for In Situ Growth, Monitoring, and Treatment of Bacterial Biofilms

Systems engineering strategies utilizing platform-based design methodologies are implemented to achieve the integration of biological and physical system components in a biomedical system. An application of this platform explored, in which an integrated microsystem is developed capable of the on-chip growth, monitoring, and treatment of bacterial biofilms for drug development and fundamental study applications. In this work, the developed systems engineering paradigm is utilized to develop a device system implementing linear array charge-coupled devices to enable real time, non-invasive, label-free monitoring of bacterial biofilms. A novel biofilm treatment method is demonstrated within the developed microsystem showing drastic increases in treatment efficacy by decreasing both bacterial biomass and cell viability within treated biofilms. Demonstration of this treatment at the microscale enables future applications of this method for the in vivo treatment of biofilm-associated infections

Replication of metal-based microscale structures by compression molding: a combined experimental and finite element analysis study

Fabrication of microscale Ta mold inserts by micro-electrical-discharge-machining (ìEDM) is reported. Morphology, chemistry, and structure of the near-surface region of as-machined Ta blanks have been characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. A TaC surface layer forms on as-machined Ta surfaces. This altered surface layer was removed by electro-chemical-polishing. Further modification of Ta insert surfaces was accomplished by deposition of a conformal Ti-containing hydrogenated carbon coating. We demonstrate successful replication of high-aspect-ratio microscale structures (HARMS) in Al and Cu by compression molding with such surface-engineered Ta mold inserts. In addition, a hybrid microfabrication technique, combining micropattern definition with LIGA (Lithographie, Galvanoformung, Abformung) fabricated Ni microstructures with parallel micropattern generation with µEDM, was used to fabricate micropattern with some geometrical complexity on elemental Ta and 304 stainless steel. Also, the results of instrumented micromolding of Al are studied. Measured molding response was rationalized with companion high-temperature tensile testing of Al using a simple mechanics model of the micromolding process. The present results suggest that stresses on the mold insert during micromolding are determined primarily by the flow stress of the molded metal at the molding temperature and the frictional traction on the sides of the insert. The influence of strain rate was also considered. In addition, the elasto-plastic response of an Al block indented by a periodic array of long smooth strip punches made of a relatively rigid material is studied through finite element analysis (FEA). First, elastic test problems, for which analytical solution exist, are carried out to calibrate the FEA mesh. Results demonstrate that satisfactory accuracy is achieved for key, peak, contact stresses near the edge-of-contact region and interior stresses. Second, indentation response is tracked with FEA into the elasto-plastic regime. Results show that the yield region within the indented material approaches a self-similar state as indentation progresses. Finally, Al molded by Si inserts at room temperature is studied through experiment and FEA

Noise Analysis and Noise-based Optimization for Resonant MEMS Structures

This paper presents a detailed noise analysis and a noise-based optimization procedure for resonant MEMS structures. A design for high sensitivity of MEMS structures needs to take into account the noise shaping induced by damping phenomena at micro scale. The existing literature presents detailed models for the damping at microscale, but usually neglects them in the noise analysis process, assuming instead a white spectrum approximation for the mechano-thermal noise. The present work extends the implications of the complex gas-solid interaction into the field of noise analysis for mechanical sensors, and provides a semi-automatic procedure for behavioral macromodel extraction and sensor optimization with respect to signal-to-noise ratio.Comment: Submitted on behalf of EDA Publishing Association (http://irevues.inist.fr/handle/2042/16838

Performance Exploration of Uncertain RF MEMS Switch Design with Uniform Meanders

The design of RF-MEMS Switch is useful for future artificial intelligence applications. Radio detection and range estimation has been employed with RF MEMS technology. Attenuators, limiters, phase shifters, T/R switches, and adjustable matching networks are components of RF MEMS. The proposed RF MEMS technology has been introduced in T/R modules, lenses, reflect arrays, sub arrays and switching beam formers. The uncertain RF MEMS switches have been faced many issues like switching and voltage alterations. This study aims in the direction of design, simulation, model along with RF MEMS switching analysis including consistent curving or meandering. The proposed RF MEMS Switch is a flexure form of the Meanders that attain minimal power in nominal voltage. Moreover, this research work highlights the materials assortment in case of beam along with signal-based dielectric. The performance analysis is demonstrated for various materials that have been utilized in the design purpose. Further, better isolation is accomplished at the range of -31dB necessary regarding 8.06V pull-in voltage through a spring constant valued at 3.588N/m, switching capacitance analysis has been found to be 103 fF at ON state and 7.03pF at OFF state and the proposed switch is optimized to work at 38GHz. The designed RF MEMS switch is giving 30% voltage improvement; switching frequency is improved by 21.32% had been attained, which are outperformance the methodology and compete with present technology