Subjects

-N 0-9

MICROELECTROMECHANICAL SYSTEMS

	Design and Analysis of MEMS-based Microballoon Actuators for Aerodynamic Control of Flight Vehicles Author : Murthy, A. Linga;Krishna, Y Source : Defence Science Journal ; Vol:59(6) ; 2009 ; pp 642-649 Subject : MICROELECTROMECHANICAL SYSTEMS Keywords : Micro-ElectroMechanical Systems Abstract : The development of microelectromechanical systems (MEMS) technology and the suitability and compatibility of sizes of microactuators with the boundary layer thickness fueled the active flow separation control to gain the air flow momentum for the last few years. The present paper deals with the development of a robust, largedeflection, and large-force MEMS-based microballoon actuator for aerodynamic control of flight vehicles such as projectiles, micro air vehicles, aircrafts, etc. Experiments were carried out on the scaled-up models for different input pressure conditions to study the response of microballoon actuator. To evaluate the performance of the microballoon actuators, simulation studies on MEMS scale models were conducted in the CoventorWare environment. Simulation studies involving static and dynamic analyses have been carried-out on the microballoon actuator models. Various geometric and input parameters influencing the behaviour of the microballoon actuator were investigated. It has been observed that a maximum deflection of 1.2 mm to 1.5 mm can be achieved using microballoon actuators and the maximum operational frequency of 60 Hz to 80 Hz can be used for the operation of microballoon actuators. Also, the sizes of the microballoon actuators designed are compatible and suitable to be used in turbulent boundary layer of aerodynamic flight vehicles.
	Deformable Membrane Mirror for Wavefront Correction Author : Gupta, Amita;Kumar, Shailesh;Singh, Ranvir;Chaudhary, Monika;Meena, A.K;Sarvanan, V.K. Source : Defence Science Journal ; Vol:59(6) ; 2009 ; pp 590-594 Subject : MICROELECTROMECHANICAL SYSTEMS Keywords : Microelectromechanical systems Abstract : Deformable or adaptive mirrors are used in modern adaptive optics systems for direct correction of the aberrations in the light wavefront. Conventional deformable mirrors used for this purpose are expensive electromechanical devices. Deformable membrane mirror fabricated using microelectromechanical systems (MEMS) technology is a low cost, compact adaptive optical element for correction of the lower-order optical aberrations such as defocus and astigmatism. In this paper, important aspects of device design and simulation, fabrication techniques, and test results are discussed.
	Fabrication of Polymeric Microcantilevers Author : Thomas, K.A.;Singh, Akash;Natarajan, V Source : Defence Science Journal ; Vol:59(6) ; 2009 ; pp 616-621 Subject : MICROELECTROMECHANICAL SYSTEMS Keywords : Micro-ElectroMechanical Systems Abstract : Polymer cantilevers are used widely in sensing applications using different transduction methods. In this paper, a polymer microcantilever is made using microstereolithography (MSL). The MSL is the latest technology emerged from applied optical instrumentation by which the micron-size structures can be created by the photopolymersation of monomers. Cantilever length, breadth, thickness, and seismic mass attached at the free end of the cantilever decide the output voltage generated by the sensor. The effect of these design parameters on the output voltage of the sensor has been studied. The microstructure fabrication process is optimised by studying the effect of laser wavelength, laser energy, scanning speed, and photoinitiator concentration on curing width and depth, that are the critical parameters that control the resolution of the fabricated structure. A cantilever design is made of 10 x 2 x 1 mm size in CimCAD and the cantilever structure is fabricated from the CAD design using the optimised values obtained from analytical and experimental study
	Microelectromechnical Systems Inertial Measurement Unit Error Modelling and Error Analysis for Low-cost Strapdown Inertial Navigation System Author : Ramalingam, R.;Anitha, G.;Shanmugam, J. Source : Defence Science Journal ; Vol:59(6) ; 2009 ; pp 650-658 Subject : MICROELECTROMECHANICAL SYSTEMS Keywords : Microelectromechanical systems Abstract : This paper presents error modelling and error analysis of microelectromechnical systems (MEMS) inertial measurement unit (IMU) for a low-cost strapdown inertial navigation system (INS). The INS consists of IMU and navigation processor. The IMU provides acceleration and angular rate of the vehicle in all the three axes. In this paper, errors that affect the MEMS IMU, which is of low cost and less volume, are stochastically modelled and analysed using Allan variance. Wavelet decomposition has been introduced to remove the high frequency noise that affects the sensors to obtain the original values of angular rates and accelerations with less noise. This increases the accuracy of the strapdown INS. The results show the effect of errors in the output of sensors, easy interpretation of random errors by Allan variance, the increase in the accuracy when wavelet decomposition is used for denoising inertial sensor raw data.
	Meshless Analysis of Radio Frequency Microelectromechanical Systems Shunt Switch Author : Kanthamani, S.;Vijay Mohan, S.;Raju, S.;Abhaikumar, V;Mohan, V. Source : Defence Science Journal ; Vol:59(6) ; 2009 ; pp 622-626 Subject : MICROELECTROMECHANICAL SYSTEMS Keywords : Microelectromechanical systems Abstract : Microelectromechanical systems (MEMS) have found applications in defence as well as in civilian sectors. Analysis of MEMS devices require complex 3-D meshes due to the presence of mechanical and electrostatic energy domains. On the other hand, meshless methods do not require the generation of mesh and perform the computational analysis by just sprinkling the points covering the domain. In this paper, meshless analysis of MEMS switches based on reproducing kernel particle method is reported. Numerical results for the static analysis of the switch are compared with the simulated results obtained using INTELLISUITE MEMS CAD tool.
	Complementary Metal Oxide SemiconductorsMicroelectromechanical Systems Integration Author : Saha, H.;Roy Chaudhuri, C Source : Defence Science Journal ; Vol:59(6) ; 2009 ; pp 557-567 Subject : MICROELECTROMECHANICAL SYSTEMS Keywords : MEMS Abstract : A review of the integration of the complementry metal oxide semiconductors (CMOS) circuit with the microelectromechanical systems (MEMS) structures for sensing and RF applications has been presented. Specifically, the integrated mechanical sensors, chemical gas sensors, and biochemical sensors have been discussed. Application of MEMS as switches, varactors, and inductors and their integration in RF circuits has also been highlighted. The fabrication and design challenges for the CMOS-MEMS integration have been described. A new design methodology for integration of thermal effects in an integrated pressure sensor has been proposed.
	Global Environmental Microelectromechanical Systems Sensors: Advanced Weather Observation System Author : Kumar Das, Rajiv;Kumar Garg, Rajesh Source : Defence Science Journal ; Vol:59(6) ; 2009 ; pp 659-665 Subject : MICROELECTROMECHANICAL SYSTEMS Keywords : Microelectromechanical systems Abstract : The technological developments in microelectromechanical systems (MEMS) have resulted in conceptualisation of a next generation observation system called global environmental MEMS sensors (GEMS). GEMS consists of a large number of airborne probes that will remain suspended in the atmosphere for long durations and take in situ measurements of pressure, temperature, humidity, wind direction and velocity as these are carried by air currents. It is envisaged that GEMS network would provide a systematic understanding of the earth.s atmosphere and would improve weather forecast accuracy, well beyond the current capability. In addition to gathering meteorological data, probes could be used for environmental monitoring of particulate emissions, organic and inorganic pollutants, ozone, carbon dioxide, and chemical, biological, or nuclear contaminants. The GEMS concept requires integration of communication engineering and instrumentation with other evolving technologies. This review describes in detail the new observation system designed for environmental monitoring and its potential application in predicting cyclones and monsoon, and measurement of urban air pollution in India. The possible application of the GEMS system during military operations has also been brought out.
	Particle Manipulation by Miniaturised Dielectrophoretic Devices Author : Tay, Francis E.H.;Yu, Liming;Iliescu, Ciprian Source : Defence Science Journal ; Vol:59(6) ; 2009 ; pp 595-604 Subject : MICROELECTROMECHANICAL SYSTEMS Keywords : Micro-ElectroMechanical Systems Abstract : This paper presents a review of dielectrophoresis (DEP) devices which provide an effective way to manipulate and separate micro- or nano-bioparticles automatically and quickly by polarisation effects in a nonuniform electric field. A detailed review for designs and operation principles of various microfabricated DEP devicesis given and some advantages and disadvantages of current devices are noted to the final system to attain the unprecedented levels of performance.
	Experimental Techniques for the Measurement of Mechanical Properties of Materials Used in Microelectromechanical Systems Author : Kamat, Samir V. Source : Defence Science Journal ; Vol:59(6) ; 2009 ; pp 605-615 Subject : MICROELECTROMECHANICAL SYSTEMS Keywords : Microelectromechanical systems Abstract : The knowledge of mechanical properties of materials used in microelectromechanical systems (MEMS) devices is critical not only in designing structures such as cantilevers and beams but also for ensuring their reliability during operation of these devices. It has been established that the mechanical properties are scaleand- process-dependent, and hence it is essential to measure the mechanical properties of these materials at the same length scale and using the same process as that used in their usage in MEMS devices. The various experimental techniques in vogue to measure the mechanical properties of these materials are briefly reviewed. The facilities established at the Defence Metallurgical Research Laboratory, Hyderabad, and their capabilities are also highlighted
	Radio Frequency Microelectromechanical Systems in Defence and Aerospace Author : Sastry, D.V.K. Source : Defence Science Journal ; Vol:59(6) ; 2009 ; pp 568-579 Subject : MICROELECTROMECHANICAL SYSTEMS Keywords : MEMS in defence Abstract : For all onboard systems applications, it is important to have very low-loss characteristics and low power consumption coupled with size reduction. The controls and instrumentation in defence and aerospace continually calls for newer technologies and developments. One such technology showing remarkable potential over the years is radio frequency microelectromechanical systems (RF MEMS) which have already made their presence felt prominently by offering replacement in radar and communication systems with high quality factors and precise tunability. The RF MEMS components have emerged as potential candidates for defence and aerospace applications. The core theme of this paper is to drive home the fact that the limitations faced by the current RF devices can be overcome by the flexibility and better device performance characteristics of RF MEMS components, which ultimately propagate the device level benefits to the final system to attain the unprecedented levels of performance.