bluuebunny/crossref_metadata_2025 huggingface dataset:
Highly Integrated Solid Propellant Micro-Thrusters Using SOI Wafers
Authors: Briand Danick , Pham Phuong-Quyen , de Rooij Nicolaas F.
Published: August 2008

With the development of micro- and nano-spacecrafts, propulsion systems need to be miniaturized in order to reach smaller dimensions, volumes and weights. To reach this goal, we are developing a micropropulsion system composed of an array of solid-propellant micro-thrusters to be integrated in a nanosatellite. The highly integrated thrusters array is composed of suspended Joule heating silicon igniters with integrated nozzles made using silicon-on-insulator wafers. The igniter/nozzle part is bonded to a micromachined chamber made of Foturan glass previously filled with a solid-propellant, zirconium potassium perchlorate (ZPP). The integration of the igniter and nozzle part in the same wafer simplifies the processing, assembling and propellant filling procedures compared to the work previously reported in this field. Moreover, the combination of this thruster’s architecture with the ZPP propellant has allowed reducing the diameter of a single thruster’s cell to 0.5 mm. The successful ignition, in a constant current mode, of the propellant was achieved at a total power of 225 to 400 mW with an ignition time of 5–20 ms. A thrust pulse was generated with a combustion time of 20–30 ms.
Micro (Cost) Technologies for Spacecraft Control and Command: An Example, Balloon-Borne Stabilised Gondolas
Authors: Laurens Andre´
Published: August 2008

Balloons are long-time known space vehicles for science missions and technology in-flight experiments, with instruments that need out-of-atmosphere or in-situ measurements, thus being complementary to the satellite. They carry micro (few hundred grams) to mega (few tons) payloads, but all of them require micro cost, short development, multiple flights. Among the big ones, CNES stabilised gondolas are versatile space platforms used to fly science instruments mainly coming for aeronomy and astrophysics communities, and requiring stabilisation and pointing capabilities, analogous to satellite attitude control subsystems. For them, cost and development constraints cannot be met without highly flexible architectures and off-the-shelf components. In order to increase gondola flexibility to new missions (or adaptability to mission evolutions), new hardware and software solution have been studied for control & command, including stabilisation and pointing functions. Promoted technologies are those of industrial computers, ground networks, free software and, over all, Ada language, for they are open, standard, powerful, low-cost and long-lasting solutions. After a brief description of domain-oriented characteristics of the stabilised gondola control & command, this paper introduces the various technologies and main design principles proposed to meet system-level goals. Then focus is put on on-board architectures: full Ada95 real-time distributed applications on an Ethernet-IP LAN of industrial PCs running Linux, and describes the prototyping work and preliminary development done to ensure feasibility. The paper then discusses the applicability of such solutions to global, ground-to-board, distributed control & command applications, through an IP-based telemetry & telecommand link, such as the one under development in CNES for balloon systems. As a conclusion, this paper shows how adoption of these technologies for other space programs such as satellite platforms and payloads may change design, development costs, duration and organisation, as well as it may open new ways in ground-to-board communication and spacecraft operation.
Development, Manufacturing and Verification of Micro-Electro-Mechanical (MEM) Louvres
Authors: Reichenberger Klaus , Matovic Jovan
Published: August 2008

MAGNA STEYR Space Technology was authorised by the European Space Agency (ESA) to develop to breadboard level a low mass micro engineered device able to change the heat rejection capability of a radiator and to protect it against external radiation variations. Previous works of MAGNA in the field of thermal control systems was the thermal design, manufacturing and verification of the ROSETTA thermal Louvres [5]. Thermal Louvres in satellite applications are used for thermal control to avoid overheating of the new generation satellites by exposed or shadowed radiator area. The closing and opening of the louvers wings is performed by thermal controlled actuators. The Louvres system is designed to be controlled by solar radiation. The challenge in the project was the design, manufacturing and verification of louvers with less mass but higher efficiency than current louvers.
MEMS Based One Shot Electro-Thermal Micro-Switches for System Reconfiguration
Authors: Pennarun Pierre , Rossi Carole , Esteve Daniel , Lagrange Denis
Published: August 2008

A new concept of one shot micro-switches is proposed. Different switches have been developed to achieve either ON-OFF switching or OFF-ON switching. They are based on electrothermal mechanisms. ON-OFF switching consists in breaking an electrical connection using energetic material or low melting point metal like aluminum. OFF-ON switching consists in micro-soldering locally two electrical connections. Switches commute with a few hundred of mW and do not need energy to stay in the stable OFF or ON state. These switches are particularly adapted to spatial redundancy applications that need high quality contact and reliable commutation even after long time storage. The fabrication process of these switches is based on classic MEMS technology steps (LPCVD, PECVD, copper electrodeposition, lift-off and plasma etching) and is IC compatible. Fabrication yield reaches 99%.
Molecular Dynamics Modeling of Thermal Conductivity of Engineering Fluids and Its Enhancement Due to Nanoparticle Inclusion
Authors: Sobhan C. B. , Mathew Nithin , Ratnapal Rahul , Sankar N.
Published: August 2008

A theoretical methodology based on molecular dynamics modeling, for the estimation of the enhancement of the thermal conductivity of fluids by the introduction of suspended metallic nanoparticles is proposed here. This involves the process of generating the atomic trajectories of a system of a finite number of particles by direct integration of the classical Newton’s equations of motion, with appropriate interatomic potentials and application of suitable initial and boundary conditions. Algorithms are made for simulating the nanofluid abiding the procedural steps of the Molecular Dynamics method. The method is presented as a means to solve the generic problem of thermal conductivity enhancement of liquids in the presence of nanoparticles, and illustrated using a specific simulation procedure with properties representing water and platinum nanoparticles. The thermal conductivity enhancement in the base fluid due to suspension of nanoparticles, estimated using Molecular dynamics simulations are compared with existing experimental results and those predicted by conventional effective medium theories. Parametric studies are conducted to obtain the variation of thermal conductivity enhancement with the temperature, and the volume fraction of the nanoparticles in the suspension.
Monolithic Silicon-Based Microthruster for Orbital and Attitude Control Fabricated by Using MEMS Technologies
Authors: Chiarini Marco , Cerabolini Paolo , Pennestri` Giuseppe , Bentini Gian G. , Cocomazzi Roberto , Cerutti Annalisa , Nubile Alessio
Published: August 2008

In the last decades there has been an increasing development of small satellites allowing remarkable reduction of both cost and fabrication time. In parallel, there has been a general increase of LEO missions for Earth observation based on small satellites. The miniaturization technologies developed in the 80’s have allowed the development of microsensors and microactuators compatible with applications on microsatelites. This trend has stimulated the need of microthrusters to maintain orbital and attitude control requiring thrust ranging from some micro-Newton to some milli-Newton. In this work is described the design and development of a Micro Thruster, monolithically fabricated in Silicon with photolithographic technologies usually applied for MEMS fabrication. The thrust is obtained by using, as propellant, high concentration H2O2 that is induced to the liquid-to-vapour phase exothermal transition by means of a suitable catalyst. Design parameters, fabrication details as well as preliminary tests will be presented and discussed.
Bio-Inspired Micro-Drills for Future Planetary Exploration
Authors: Menon C. , Vincent J. F. V. , Lan N. , Bilhaut L. , Ellery A. , Gao Y. , Zangani D. , Carosio S. , Manning C. , Jaddou M. , Eckersley S.
Published: August 2008

In a domain such as space technology, where robustness, mass, volume and power efficiency are key, biological organisms may provide inspiration for new systems with high performance. By using micro-technology processes, designers of space systems may take advantage of the millions of years over which miniaturised mechanisms in plants and animals have been optimised for survival. Space exploration often requires systems equipped with drills, and miniaturised drillers could enable a number of new space operations. Two natural digging systems have been studied as potential miniature space digging systems; the ovipositors of the female locust and of sirex noctilio, a species of woodwasp. Being insectoid systems, the mechanics of their design work on an inherently small scale, though they are also thought to be scalable. Results of preliminary studies, performed during collaboration between the Advanced Concepts Team of ESA, the University of Bath, the University of Surrey, D’appolonia and EADS-Astrium, are presented and discussed. Engineering solutions are proposed and analysed to assess the potential of new bio-inspired miniaturised digging systems for space applications.
Towards Multifunctional Characteristics of Embedded Structures With Carbon Nanotube Yarns
Authors: Hernandez Corey D. , Gates Thomas S. , Kahng Seun K.
Published: August 2008

This paper presents recent results on research of achieving multifunctional structures utilizing Carbon Nanotube (CNT) yarns. The investigation centers on creating composite structures with CNT yarns to simultaneously achieve increases in mechanical strength and the ability to sense strain. The CNT yarns used in our experiments are of the single-ply and two-ply variety with the single-ply yarns having diameters on the order of 10–20 μm. The yarns are embedded in silicon rubber and polyurethane test specimens. Mechanical tests show an increase in modulus of elasticity, with an additional weight increase of far less than one-percent. Sensing characteristics of the yarns are investigated on stainless steel test beams in an electrical bridge configuration, and are observed to have a strain sensitivity of 0.7mV/V/1000 micro-strain. Also reported are measurements of the average strain distribution along the direction of the CNT yarns on square silicon rubber membranes.
The EADS Micropack Project: An Intelligent Microsystem Demonstrator for Small Mission Applications
Authors: Eckersley Steven , Schalk Josef , Kluge Martin
Published: August 2008

The global Micro-electromechanical (MEMS) or Microsystems Technology (MST) market is forecast to keep growing at a phenomenal rate. EADS recognises the potential for this technology to revolutionise the space industry, where it can dramatically reduce mass, size and power requirements and therefore launch costs. This can enable missions that would otherwise have been unfeasibly expensive. Therefore EADS has been developing a novel modular approach to packaging integrated microsystems for space applications called ‘micropacks’. The micropacks include suites of COTS MST sensors, packaged and integrated into a 3D modular multi-layer ceramic package. This introduces flexibility and means that this impressively light and compact micropack technology can be adapted to form the basis as a solution for a range of exciting future mission concepts. In addition, EADS Astrium Ltd. is ensuring that the micropack has the capability to be integrated into a cubesat, should a potential flight opportunity arise. This in turn helps develop the necessary knowhow of MEMS payload integration for future missions.
The ESA Nanosatellite Beacons for Space Weather Monitoring Study: An Ideal Mission Opportunity for MEMS
Authors: Hapgood M. , Eckersley S. , Lundin R. , Kluge M. , Prechtel U. , Hyvo¨nen P.
Published: August 2008

This paper presents preliminary results from this ESA-funded study, which started in November 2004 and is now under final review by ESA, due for public release later this year. The primary aim of the study has been to investigate how current and emerging concepts for nanosats may be used to monitor space weather conditions and provide improved access to data needed for space weather services. The study has reviewed present and future micro and nano-technology developments that could be used to implement space weather monitoring by nanosats. It has also has established a set of space weather measurement requirements appropriate to nanosats solutions and developed a set of instrument and spacecraft solutions to address those requirements. These were then subject to a detailed system and mission analysis to trade-off a range of potential mission and spacecraft architectures, and derive costs for programme development, operation and maintenance over a ten-year period. As a last step the study reviewed the results of the previous stages and developed a report on the prospects for a space weather nanosat programme and recommendations on the measures needed to enable implementation of such a programme. To support this step a small workshop was held at ESTEC following the MNT Round Table.
Environmental Chamber for Temperature and Pressure Investigations on MEMS Devices
Authors: Lellouchi Djemel , Gauffier Jean-Luc , Lafontan Xavier , Pons Patrick , Schmitt Petra , Pressecq Francis , Dhennin Je´re´mie
Published: August 2008

In this paper, we present a new tool developed for environmental testing of MEMS: the EMA (Environmental MEMS Analyzer) 3D. Based on white light profilometry coupled with an environmental chamber, it permits large temperature scale and different pressure testing. This system has been used to characterize the environmental behavior of two types of RF MEMS, from −20 to 200°C.
Variable Emissivity Surfaces for Micro and Nanosatellites
Authors: Matovic J. , Vujanic A. , Reichenberger K.
Published: August 2008

The contemporary satellites usually utilize louvers as variable emissivity surfaces (VES) for the thermal control subsystem. This means is only particularly scalable down and the next generation of small satellites definitely requires new techniques for thermal control. Further, the low mass, volume and cost of the micro and nanosatellite require additional features from the future VES. Besides high reliability, which is an unconditional requirement for a space application, the other criteria are as follows: low mass, deep modulation of emissivity, low heat leak in off-state, fast reaction time, passive action, as well as other lower level criteria. These requirements are complex and sometimes contradictory. The current approaches to find alternatives to the traditional mechanical louvers branch in several directions: electrophoretic, electrochromic, electrostatics actuated VES, MEMS shutters, etc. None of the current solutions is successful in meeting all of the posed criteria. We present a novel VES subsystem, particularly developed for use in micro and nanosatellites. The concept is simple, reliable and very efficient. The bionic structure, a flower-like design, is made from a thin and elastic foil. The artificial flower consists from a peduncle, fixed to the satellite radiator panel and 4–6 petals. The upper surface of the petal is made as the second-surface mirror and the lower surface is the gold plated or the first-surface mirror. The kinematic mechanism which opens and closes the artificial flower is the shape memory actuator located in the petal root. The SMA actuators are trained as the “two way actuators”. The “two way” memory effect has been recognized as difficult to control and suffering from amnesia. However, the new learning process of the shape memory actuators enables more than 350.000 cycles without SMA parameter degradation. The artificial flower works as follow: when the sun irradiates the flower and/or the radiator temperature exceeds the preset value, the SMA actuators bend and open the flower. In such a manner the flower exposes the highly reflective surface to the sun and shadows the satellite radiator until the sun sets again. The flower structure is without any friction-connected kinematic movements, thus the reliability of device should be high. The mass of the flower is less than 450 g/m2, the heat leak trough the open flower is >2% and the efficiency of the closed flower is <80%. The SMA actuator is passive and quite resistant to the radiation, oxygen and EDS.
Micro Fiber Optical Sensor Interrogation Systems for Aerospace Applications
Authors: Xiao Gao Zhi , Mrad Nezih
Published: August 2008

The emerging field of microsystems technology is enabling the innovative development of a micro optical fiber interrogation system for potential integration into air platforms structural health monitoring and management capabilities. Our efforts in such development is based on micron size optical waveguides using arrayed waveguide gratings (AWG) based demultiplexer for highly multiplexed fiber Bragg grating (FBG) sensor arrays. In this document, a proposed system concept, its operating principle and proposed interrogation methodology are presented. Initial results demonstrate the ability of the system to obtain measurement resolution of 1 pm or better (equivalent to 0.1°C for temperature sensing) and response time as short as two milli-second. Owing to the small size and ruggedness of AWG, it is potentially feasible to fabricate an all solid state (no moving parts), palm size, robust and high-resolution interrogation system that responds to air platform requirements.
A Multipurpose Flexible Photonic Integrated Micro Device for Space and Earth Applications Based on a Tuneable Resonating Micro Cavity on LiNbO3
Authors: Chiarini Marco , Cerabolini Paolo , Pennestri` Giuseppe , Bentini Gian G. , Bianconi Marco , Cerutti Annalisa , Nubile Alessio , Sugliani Simone , Gallerani Letizia , Guzzi Rodolfo
Published: August 2008

Photonic crystals are attracting great interest because of the possibility to functionalize surfaces and materials and to obtain integrated devices suitable for the implementation of different optical functions. These systems can be used to fulfil a specific function (Filtering, Amplifying, Switching, Shifting, etc.) but can also be integrated in more complex hybrid systems, including optical and electronic signals, suitable for performing more complex functions. The application of such devices can span from Telecommunications, Space Applications to Ambient Safety or Security Monitoring. In this work the design and development of an integrated photonic micro-device, fabricated on single crystal LiNbO3 substrates, by using non-standard processes such as Deep UV laser lithography and High Energy Ion Implantation techniques, is described. The structure is composed by two linear Bragg Gratings fabricated on a channel or planar optical waveguide. By fixing proper gratings dimensions, it is possible to generate an optical micro-cavity, resonant with specific optical wavelengths. In the case of LiNbO3 an electric field can be applied along the crystal c-axis, in order to exploit its electro-optical properties and obtain a tuneable effect on both the mirrors and the cavity. In order to generate a multipurpose micro-device, a receptacle of suitable size has been created in between the two mirrors. The receptacle can be filled with different optical items, depending on the function to be accomplished. Design and fabrication details together with preliminary performance tests of the new photonic device will be presented.
Novel Surface-Micromachined Micromirrors for Optical MEMS Beam Manipulators
Authors: He S. , Ben Mrad R.
Published: August 2008

A novel surface-micromachined electrostatic rotation micromirror is presented. The micromirror can be used to develop high performance optical beam steering manipulators for space applications based on an array of such micromirrors which are controlled by a feedback controller to compensate for jitter and misalignment during optical metrology or communication. The rotation micromirror has a two-layer structure and uses two repulsive force electrostatic actuators which generate a force to rotate the mirror out-of-plane. The rotation angle of the micromirror is not limited by the initial gap distance between the mirror plate and the substrate. By using repulsive force actuators, the surface-micromachined rotation micromirror can achieve a large rotation angle for a large mirror size without requiring any post-release assembly to fold the mirror out or raise it up. Prototypes fabricated using MUMPs are characterized by a mirror size of 312 μm × 312 μm, a stiffness of 0.485e−8Nm/rad, a mechanical rotation of 0° ∼ 2.2° at a driving voltage of 0 ∼ 200 V.
Contemporary Technology and Application of MEMS Rocket
Authors: Takahashi Koji
Published: August 2008

MEMS rocket array is one of the most promising propulsion systems for micro satellite. Its recent development researches have reached close to practical devices. This paper reviews the performances and maturities of recently-build MEMS rockets. Four MEMS rocket projects are treated; LAAS-CNRS, France, Tohoku University, Japan, National University of Singapore, and Kyushu University, Japan. Their design, size, propellant, etc. are explained. The smallest MEMS rocket of Kyushu University using DDNP propellant and PDMS micro tank is also introduced.
Using the Modeshapes of a Vibrating PVDF Film as a Deformable Mirror Surface
Authors: Tahtali Murat , Lambert Andrew J. , Zhitao Zheng , Fraser Don
Published: August 2008

One of the challenges of all telescope imaging is the adverse effects of atmospheric turbulence in the optical path. These effects can be mitigated by the use of Adaptive Optics (AO) and Digital Image Processing (DIP). However, it is always desirable to correct as much as possible with AO prior to attempt any further corrections with DIP as more of the original signal can be retained by optical means. The central element of a modern adaptive optics system is its deformable mirror which can be considered as a micro-mechanical device. The surface curvature is made to vary by means of an array of actuators of different technologies and a bank of sophisticated control circuitry. The basic idea is to reproduce the opposite aberration on the mirror surface as a combination of fundamental deformations described by a set of polynomials called Zernike polynomials. The plots of these Zernike polynomials bear great resemblance to the modeshapes of a circular membrane under tension. In this paper, we are presenting encouraging test results of a vibrating PVDF (Polyvinylidene fluoride) film at its natural frequencies. The possibility of using inexpensive PVDF deformable mirrors has the prospect of increasing the speed as well as the affordability of adaptive optics systems while reducing their complexity. An emerging field of application for lightweight and low cost AO systems is the next generation of micro UAVs (Unmanned Aerial Vehicles).
Thermoelastic Damping in Vibrating Beam Accelerometer: A New Thermoelastic Finite Element Approach
Authors: Lepage S. , Le Traon O. , Klapka I. , Masson S. , Golinval J. C.
Published: August 2008

In order to respond to the demand of accurate miniature inertial navigation systems, ONERA has been working on the design of a vibrating beam accelerometer called the Vibrating Inertial Accelerometer (VIA). The accuracy of the VIA is directly related to the thermoelastic quality factor of its sensitive element, which is a beam made of quartz. In this work, thermo-piezoelectric finite element analyses of the beam are carried out in order to determine its thermoelastic quality factor. These finite element results are compared to the analytical and experimental quality factors. Due to their inherent restrictive assumptions, analytical models overestimate the quality factor while the finite element results are in good agreement with the experimental values. As the finite element model allows to take into account the real geometry of the beam and the piezoelectricity of the material, it allows to quantify more precisely the thermoelastic quality factor.
On Exploring Application of MEMS in Aerodynamic Flow Control
Authors: Deng Jin-Jun , Yuan Wei-Zheng , Ma Bing-He , Liu Kui , Wang Yan
Published: August 2008

This paper presents an overview of research activities in MEMS/NEMS Lab of NWPU on applying MEMS to aerodynamic flow control domain. For the purpose of flow separation control, a kind of bubble actuator array was developed and fabricated. By mounted on the leading edge of the aerofoil, its feasibility for flow control has been demonstrated through wind-tunnel tests. In order to obtain flow state and determine the best actuation location for micro-actuator array, micro shear-stress sensor arrays have been investigated. An integration method of micro-sensors array was developed based on flexible PCB technology. Using this flexible substrate, micro-sensor arrays can be attached upon the surface of aircraft key position to realize distributed and realtime measurement of flow parameter.
MEMS Integrated Electro-Fluid-Elastic Modeling for Aerospace Applications
Authors: Fumagalli Alessandro , Quaranta Giuseppe , Mantegazza Paolo
Published: August 2008

MEMS physics is characterized by multi-fields interactions. In this paper, a fully integrated methodology is proposed for dynamical analysis of electro-fluid-elastic systems, typical of MEMS-based microresonators and microswitches. Finite Elements/Volumes Method is used to solve field equations. These are coupled by an opportune procedure of interface between domains, resulting in a nonlinear algebraic differential system of equations describing the system. This is directly integrated in time, becoming fully algebraic, and solved by a Newton technique. Full Jacobian matrix computation results in a very hard task. Analytical block approximation for Jacobian matrix is proposed. Model is validated comparing results with commercial codes and with published data, showing good agreement, high convergence properties and reduced computational efforts.
Two Dimensional Scanning LIDAR for Planetary Explorer
Authors: Mizuno Takahide , Mita Makoto , Takahara Takuya , Hamada Yusuke , Takeyama Norihide , Takahashi Takuya , Toshiyoshi Hiroshi
Published: August 2008

The two-dimensional scanning LIDAR system which used MEMS technology is proposed. The specification of LIDAR under development are measurable range of 50m–50km, ±5 degrees of scanning angles, 10Hz repetition rate, and ±1m in range finding accuracy. By adopting monolithic YAG laser as a laser source, the tolerance over machine vibration has been improved with volume and weight saving. For a transmitting laser scan, adoption of a magnetic resonance drive type single micro-mirror is considered. In this system, we propose a novel method on the beam scanning mechanism for a receiver telescope with big aperture by using MEMS technology. The scanning optics system of receiver telescope is composed by a telecentric telescope and a micro shutter array. This optical system has achieved a narrow viewing angle corresponding to aperture of the shutter by limiting the view of the telescope that has a wide viewing angle with the shutter. The basic function of the scanning system of receiver optics is already checked experimentally.
Hermeticity Assessment of MEMS Micro Packages: Leak Rate Measurements Based on Infrared Spectroscopy
Authors: Veyrie´ David , Lellouchi Djemel , Roux Jean-Luc , Pressecq Francis , Tetelin Ange´lique , Pellet Claude
Published: August 2008

This paper presents an alternative method for the hermeticity assessment of MEMS micro-packages, and the first experiments performed using this technique. The method consists in monitoring the internal gas pressure of the cavity by Fourier Transform Infra Red (FTIR) spectroscopy. The package’s hermeticity is then deduced from the pressure variations. In order to carry out the IR transmission measurements, nitrous oxide was chosen as bombing gas due to its excellent absorption properties for mid-IR radiations. The method was applied to BCB-sealed silicon micro-packages and allowed to study the influence of different parameters like the sealing ring dimensions or the internal volume on their hermeticity. Additional measurements were carried out on hermetic packages, with an additional organic coating. These experiments validated the method for micro-packages with a volume of 5 mm3 or more.
High Temperature (800°C) MEMS Pressure Sensor Development Including Reusable Packaging for Rocket Engine Applications
Authors: Fricke So¨ren , Friedberger Alois , Ziemann Thomas , Rose Eberhard , Mu¨ller Gerhard , Telitschkin Dimitri , Ziegenhagen Stefan , Seidel Helmut , Schmid Ulrich
Published: August 2008

For aircraft and rocket engines there is a strong need to measure the pressure in the propulsion system at high temperature (HT) with a high local resolution. Miniaturized sensor elements commercially available show decisive disadvantages. With piezoelectric-based sensors working clearly above 500°C static pressures can not be measured. Optical sensors are very expensive and require complex electronics. SiC sensor prototypes are operated up to 650°C, but require high technological efforts. The present approach is based on resistors placed on top of a 2 mm diameter sapphire membrane (8 mm chip diameter). The strain gauges are made either of antimony doped tin oxide (SnO2:Sb) or platinum (Pt). This material combination allows for matching the thermal coefficients of expansion (TCE) of the materials involved. The morphology of the SnO2:Sb layer can be optimized to reduce surface roughness on the nanometer scale and hence, gas sensitivity. Antimony doping increases conductivity, but decreases the gauge factor. With this nanotechnological knowledge it is possible to adjust the material properties to the needs of our aerospace applications. Tin oxide was shown to be very stable at HT. We also measured a 2.5% change in electrical resistivity at room temperature at maximum membrane deflection. The maximum temperature coefficient of resistivity (TCR) is less than 3.5·10−4 K−1 in the temperature range between 25°C and 640°C. In addition to the device related research work, a novel reusable packaging concept is developed as housing is the main cost driver. After the chip is destroyed the functional device can simply be replaced — housing and contacts can be reused. The MEMS device is electrically contacted with a miniaturized spring mechanism. It is loaded from the harsh environment side into the HT stable metal housing. A cap is screwed into the housing and compresses the inserted seal ring against the chip. The part for electrical contacting on the opposite housing side is not disassembled. The MEMS device is not in direct contact with the housing material, but embedded between two adaptive layers of the same material as the device (sapphire) to decrease thermally induced mechanical stress. Overall weight is 46 g. This packaging concept has been successfully optimized so that the whole assembly can withstand 800°C and simultaneously provides sealing up to 250 bar! After testing in such harsh environment, the small packaging can still be unscrewed to exchange the MEMS device. Due to the reutilization, the packaging can be used far beyond the lifetime of HT MEMS devices.
Low Maintenance MEMS Packaging for Rotor Blade Integration
Authors: Friedberger A. , Gradolph C. , Ziemann T. , Mu¨ller G. , Wilde J.
Published: August 2008

Rotor blade integrated MEMS pressure sensors can be used for detecting and quantifying BVI on helicopter blades. The sensor package we present here is predestined for this application because it protects sensitive measurement parts from harsh environmental conditions. Maintenance effort and time can be reduced in case of sensor malfunction due to its two-component package, consisting of sensor carrier and a capsule which can be easily replaced.
Silicon MEMS Pressure Sensors for Aerospace Applications
Authors: Nese Martin , Seeberg Bjo̸rn Erik
Published: August 2008

A novel piezoresistive silicon MEMS pressure sensor has been developed for full-scale measurement from 10 bar to > 1000 bar for high-precision oil & gas, aerospace and space applications. The silicon element has a tubular design with an externally stable resistor bridge to detect the pressure-induced stress. The fabrication process is by silicon planar technology and MEMS processes, such as silicon fusion bonding and electrochemical etching. The concept is favorable in rough field applications due to several key properties from small dimensions and deflections, high material rigidity, symmetry, a large output signal, fast pressure and temperature response and low acceleration sensitivity. The overload capability is several times the full-scale, since pressure mainly generates compressive stress. Long-term and hysteresis effects are minimized by eliminating the package-induced stress due to a relatively large distance from the die attach to the sensitive region. Total accuracy for a pressure range 700 bar and a wide temperature range −7 to 135°C is better than 0.01%FS. Typical hysteresis and repeatability is ± 10 ppm.
Satellite-on-a-Chip Development for Future Distributed Space Missions
Authors: Barnhart David J. , Vladimirova Tanya , Sweeting Martin N.
Published: August 2008

A new dimension of space mission architectures is emerging where hundreds to thousands of very small satellites will collectively perform missions in a distributed fashion. To support this architecture, high volume production of femto-scale satellites at low cost is required. This paper reviews current and emerging distributed space systems. A conceptual design of SpaceChip, which is a monolithic “satellite-on-a-chip” based on commercial CMOS technology is detailed. Assessment of the SpaceChip design is given and its use in future distributed space missions is discussed.
Micromachined Hot-Wire Boundary Layer Flow Imaging Array
Authors: Yang Yingchen , Pandya Saunvit , Chen Jack , Engel Jonathan , Chen Nannan , Liu Chang
Published: August 2008

Boundary layer flow imaging can provide real time information for flight control of air vehicles, and collision avoidance and stealth detection of underwater vehicles. High density, micro-scaled sensor arrays based on microfabrication techniques have made it possible to enable these new applications. We report on the development of such a flow sensor array. It is realized by combining surface micromachining and three-dimensional assembly. It consists of a linear array of 16 integrated hot-wire anemometers (HWA) evenly spaced 1 mm apart. Each sensor uses a 400 μm long thermal element (hot-wire) that is made of a thin film nickel/polyimide composite, and is elevated 600 μm above the substrate. Under constant temperature (CT) mode, the threshold velocity sensitivity to water flow is down to 100 μm/s, and the frequency response to dynamic signals is up to 1000 Hz. The capabilities of the sensor array on boundary flow measurement and hydrodynamic wake imaging are demonstrated via wind tunnel and water channel experiments.
Intershell Coupling in Multiwalled Carbon Nanotubes
Authors: Zalamea Luis , Kim Hyonny , Pipes R. Byron
Published: August 2008

The interaction and load transfer between multiple shells of a multi-walled carbon nanotube (MWNT) is the subject of intense research by both analysts and experimentalists. Observations of both lubricated sliding and adhesion between the shells of the MWNT have been observed. While the atomic interactions due to simple separation have been successfully modeled by the Lennard-Jones interaction potential for graphene structures, modeling of the shearing deformation mode has been problematic. In the present work, the authors utilize two approaches in continuum mechanics to examine the shearing transfer between shells in a MWNT subjected to extensional and torsional loading wherein the load is transferred through the outer most shell to interior shells. The first approach follows the earlier developments of the authors wherein imperfect bonding between the shells is governed by a shearing transfer efficiency that varies between perfect bonding and frictionless sliding. The second approach utilizes a classical shear lag model to study the shearing transfer between the shells. A comparison between the shear lag and shear transfer models shows the equivalence of the two approaches for two-shell MWNT and numerical solutions are presented for the shear lag model for multiple layers beyond two. Agreement between the two models for multi-shells is demonstrated by varying an adjustable parameter that depends solely on the MWNT geometry. The simplicity of the shear transfer model as compared to the shear lag model constitutes an important advantage. The fundamental discrepancy between the two models lies in the fact that length dependence is inherent to the shear lag analysis, while according to the shear transfer model, stress transfer does not depend explicitly on length.
Design and Fabrication of Non-Powered MEMS Trajectory Sensors
Authors: Tassetti C.-M. , Haussy J. , Tissot A. , Leray J.-L. , Franc¸ais O. , Rousseau L.
Published: August 2008

Non-powered MEMS trajectory sensors based on a mass-spring-damped system have been designed and fabricated. The damping coefficient is provided by the displacement of a micro-piston in a chamber filled with a fluid.
Single-Walled Carbon Nanotube Micropatterns and Interconnections Fabricated With Layer-by-Layer Nano Self-Assembly and Microlithography on Flexible Substrates
Authors: Xue Wei , Cui Tianhong
Published: August 2008

The fabrication and characterization of single-walled carbon nanotube (SWNT) multilayers, micropatterns and interconnections on plastic substrates are reported in this paper. The SWNT-based multilayers and devices are fabricated with a simple, fast, inexpensive, low-temperature, and highly efficient technique combining layer-by-layer (LbL) nano self-assembly, microlithography, and lift-off techniques. The SWNT multilayers are alternating layers of SWNTs and poly (dimethyldiallylammonium chloride) (PDDA). Lithography and lift-off techniques are used to pattern the SWNT multilayers. SWNT microstructures with linewidth of 5 μm are fabricated and characterized. The thickness of a (PDDA/SWNT) bi-layer is approximately 76 Å. Two-terminal SWNT thin film based interconnections are fabricated on flexible substrates. Current-voltage (I-V) characterization and four-point probe measurement show that the resistance of the interconnection is nonlinearly inversely proportional to the number of the assembled SWNT layers. The nano-assembled polymer/SWNT composite can be used in many applications due to its low cost, light weight, and long lifetime.
Design of Packaged RF MEMS Switching Functions on Alumina Substrate
Authors: El-Khatib Mohamad H. , Pothier Arnaud , Blondy Pierre
Published: August 2008

Microwave coaxial switches used in satellites for instance are quite heavy and bulky and thus have an important after-effect on a payload cost. MEMS devices seems to bring a new alternative for compact switching matrix design which requires a large number of switching devices often incompatible with the semiconductor technology in term of dissipated power [3]. Meanwhile, the reliability of MEMS components for space applications still remains today a problem to be solved, in term of design, technology and cost of realization. Hence the component packaging appears today to be a crucial issue for these devices formed starting from mechanically deformable elements which require a stable environment, clean and deprived of moisture to function in an optimal way [1][2]. In spite of the strong integration of these components, standard packaging solutions are not appropriated for MEMS components [4]. This is why dedicated technological solutions must be developed to encapsulate the component or a group of components on the substrate by using simple techniques limited in term of technological steps.
MEMS Reliability: Accurate Measurements of Beam Stiffness Using Nanoindentation Techniques
Authors: Seguineau Ce´dric , Desmarres Jean-Michel , Dhennin Je´re´mie , Lafontan Xavier , Ignat Michel
Published: August 2008

Bending tests on suspended parts of MicroElectroMechanical System (MEMS) can be achieved thanks to nanoindentation techniques. The paper presents the main difficulties met when performing such a test, and shows how they can be reduced by experimental ways. An application is realized on gold bridges, with a validation of some theoretical assumptions.
Design and Performances of Two Quartz Monolithic Vibrating Inertial Microsensors
Authors: Masson Ste`ve , Janiaud Denis , Le Traon Olivier , Muller Serge
Published: August 2008

For several years, ONERA has been developing inertial vibrating microsensors, for military and civil applications, such as dynamic control and navigation of vehicles (coupled with radio-electric positioning system). The object of these works is to define original and accurate MEMS devices compatible with collective micromachining technologies, in order to satisfy industrial needs. This paper presents the design and the performances of two sensors : a Vibrating Beam Accelerometer (VBA), called VIA (Vibrating Inertial Accelerometer), and a Coriolis Vibrating Gyrometer (CVG), called VIG (Vibrating Integrated Gyrometer). These devices are based on monolithic structures, which are micromachined by wet etching of crystalline α-quartz substrates. The piezoelectric properties of quartz are used to both drive and detect the mechanical vibrations. The main originality of the presented designs is their specific decoupling frames, which have been developed in order to insulate the useful vibrations and to preserve the quality factor of the resonance modes. Hence energy losses represent less than 10−8 of the total vibrating energy. Thanks to these frames, it is then possible to take full advantages of the excellent mechanical properties of quartz and to achieve high accuracies. The VIA accelerometer principle is based on the frequency shift of a vibrating microcantilever, due to the axial stress generated by a proof mass submitted to an acceleration. The working frequency is around 60 kHz and the sensitivity is 24 Hz/g. Upon a measuring range of 100 g, the scale factor error is about 10 ppm and the bias error is a few hundreds of μg. The VIG uses a tuning-fork as sensitive element, which is excited at its in-plane flexural mode (driving mode). When a rotation speed is applied to this system, a transversal vibration (sensing mode) is induced by the Coriolis forces. The amplitude of this induced vibration is proportional to the rotation speed. Piezoelectricity is used for both the excitation of the driving mode and the detection of the sensing mode. The VIG measuring range is 1000 °/s, with a resolution around 0.01 °/s/√Hz and a bandwidth of 100 Hz.
An Approach to Enhancement of Conductivity in Composite Material Using Nanotechnology
Authors: Dang Vivian T. , Maguire Russ , Safa-Bakhsh Robab
Published: August 2008

This review documents possible developments using Nano technology to enhance electromagnetic effects (EME) and identifies the potential integration on the composite structures for the next generation composite commercial aircraft. First, developments using Nano technology as a source to enhance the EME of the composite will be discussed. These developments include computational modeling of Nano-filled composites to predict certain properties and behaviors of Nano-enhanced materials, test methods for non-destructive examination of Nano-modified materials, and other novel approaches to resolve the challenges of increasing conductivity in composite materials. Next, the details of the potential impacts of using Nano technology for increasing conductivity will be outlined. Finally, the implementation of a Nano-enhanced material on the composite structure will be described.
Molecular Mechanics Based Finite Element for Carbon Nanotube Modeling
Authors: Theodosiou Theodosios C. , Saravanos Dimitris A.
Published: August 2008

In this paper a new method is introduced for carbon nanotubes modeling. It combines features of Molecular Mechanics and Finite Element Analysis. This method is based on the development of a new finite element, whose internal energy is determined by the semi-empirical Brenner molecular potential model; all quantities are calculated analytically in order to gain more accuracy. The method is validated through comparisons to results provided by other researchers and are obtained either by experimental procedures or theoretical predictions. The bending and shearing of CNTs is also simulated.
Nano Sensors for Gas Detection in Space and Ground Support Applications
Authors: Medelius Pedro J.
Published: August 2008

Personnel living in a space environment as well as technicians and engineers preparing spacecraft for launch can potentially be exposed to small amounts of hazardous gases. It is therefore important to be able to detect, identify, and quantify the presence of a gas, especially when its presence could lead to a fatal situation. The use of small and sensitive sensors can allow for the placement of these devices over a large area, thus allowing for a more precise and timely determination of a gas leak. ASRC Aerospace and its research partners are developing nano sensors for the detection of various gases, including but not limited to: H2, NH3, N2O4, hydrazine, and others. Initial laboratory testing has demonstrated the capability to detect the gases in concentrations lower than parts per million. Testing and development is continuing to improve the response and recovery times, and to increase the sensitivity of the devices. Different coatings and electrodes are currently being evaluated to determine the optimum configuration for the detection of a variety of gases. The small footprint of the nano sensors allows for several devices, each responsive in a different way to different gases, to be placed into a single substrate. Multiple devices embedded into a single substrate results in increased reliability and in a decrease in the need for periodic calibrations. The use of different coatings will result in a small electronic nose capable of distinguishing between different gases. A multi-channel signal conditioner amplifier built on a small multi chip module is used to process the output of the sensors and to deliver a signal that can be remotely monitored. All the data is digitized and transmitted over the same cable pair used to power the amplifier. Multiple outputs can be connected to a single cable pair in order to minimize the added weight and expense associated with cabling in a spacecraft. The sensors will be run through a qualification process to evaluate their suitability for space applications. We are expecting to have fully functional sensors available for initial field deployment and testing by the end of the year 2006. ASRC Aerospace is the prime contractor at the Kennedy Space Center for the University Affiliated Technology Development Contract (USTDC).