CANEUS Moments

Devices & Systems:
(D1) - Nano Materials
(D2) - Nano Electronics

(D3) - MEMS Devices
(D4) - MEMS Devices
(D5) - Precision MEMS Sensors and Gyroscopes

(D6) - MEMS Devices
(D7) - Nano Devices
(D8) - Nano Materials
(D9) - Nano Electronics
(D10) - Photonics and Bio Nanotechnology
(D11) - Micro Machined Silicon Sensors and Actuators for Space Applications

Devices/Systems (D1)- Nano Materials

Session chair: Barry Stansfield, INRS, Canada


Deepak Srivastava, NASA Ames, USA
Computational Nanotechnology of Nanomaterials and Devices

Abstract: Role of computational nanotechnology in advancing the possibilities and knowledge base in nanomaterials, electronics, sensors and machines is described through use of carbon nanotubes and fullerenes in these areas. Using large-scale classical atomistic and quantum dynamics/transport simulations we discuss nanomechanics of carbon and boron-nitride nanotubes in polymer composites; branched carbon nanotube structures for molecular electronics and sensors, endo- fullerenes and diamond nanocrystals for solid-state quantum bits applications, and model operations of molecular gears and motor systems. Time permitting; examples of nano-indentation and mechano-chemistry will also be described.

Pulickel M. Ajayan, RPI, USA
Nanomaterials synthesis

This talk will focus on the directed assembly of multiwalled carbon nanotubes on planar substrates into highly organized structures that include vertically and horizontally oriented arrays, ordered fibers and porous membranes. The concept of growing such architectures is based on growth selectivity on certain surfaces compared to others. Selective placement of ordered nanotube arrays is achieved on patterned templates prepared by lithography or oxide templates with well-defined pores. Growth of nanotubes is achieved by chemical vapor deposition (CVD) using hydrocarbon precursors and vapor phase catalyst delivery. The new technique developed in our laboratory allows enormous flexibility in building a large number of complex structures based on nanotube building units. We will present our understanding of the early stages of nanotube film growth during this CVD process. It is observed that there are select pathways during the growth process of nanotube films on substrates, influencing the final morphology of the films developed, and these pathways can be tailored by tuning the catalyst concentration in the vapor phase. We will also discuss some of our recent efforts in creating nanotube junctions and networks of related nanostructured materials.

Xin Xiang Jiang, CSA, Canada
CSA's Perspective on Nano-Materials Research and its Potential Impact On Space Technologies

Devices/Systems (D2) - Nano Electronics

Session chair: Deepak Srivastava, NASA Ames, USA


Stan Williams
Duncan Stewart, HP Research Labs, USA
Molecular Electronics: the H-P Way

It has been more than 25 years since Aviram and Ratner first proposed single molecule diodes, yet only recently have we been able to approach fabrication of devices that might display such single molecule properties. In the last five years published reports have claimed single-molecule rectification, negative-differential resistance and, most recently, transistor action.

Hewlett-Packard Labs initiated a dedicated effort in molecular electronics three years ago. I will outline our work on architecture, defect tolerance and fabrication of nanowires by epitaxial growth, catalyzed CVD growth and imprint lithography as well as molecular efforts on ab into modeling, monolayer film deposition and electrical device fabrication.

I will also describe detailed electrical transport characterization of several planar electrode/ Langmuir-Blodgett molecular mono-layer /electrode systems that show electrical switching and rectifying behavior. Investigations of Al/Ti, Pt/Ti and Pt/Pt devices show different generic behaviors and confirm the dominant role played by the poorly understood electrode/molecule interface. Indeed the difficulty of controlling this electrode/molecule contact has to date prevented any correlation between theory and single-molecule experiment. We have nonetheless used the mono-layer switching characteristics to demonstrate memory and logic circuits, and have begun a systematic investigation of transport mechanisms in the simplest Pt/Pt electrode system.

Carles Ferrer, CNM, Spain
Circuit & System integration of MNT devices

During the last years, a strong research activity is being performed in the new field of Nanotechnology, i.e., in the development of the technology to fabricate, characterize and use structures from the atomic scale up to around 100 nm. Traditional models and theories for material properties and device operations involve assumptions based on "critical scale lengths" that are generally larger than 100 nm. When at least one dimension of a structure is under this critical traditional model and theories cannot explain length, distinct behavior often emerges that. Nowadays, scientists and engineers from many disciplines are fabricating and analyzing nanostructures at the intermediate scale between individual atoms/molecules and submicron structures where the novel phenomena develop.

In this way, the presentation will explain a methodological plan of circuit and system integration of nanodevices and microdevices in order to develop new to the aerospace applications. These activities will be divided into four steps:

i) Integration of nanofabrication processes and methods for the combination of microtechnology and nanofabrication.
ii) Development of nanostructures and nanodevices.
iii) Development of circuits and systems design and architecture concepts to interconnect and combine nanoelectronic and nanomechanical devices with the CMOS circuits.
iv) To focused the activities towards some specific application, mainly with pre-industrial interest for the aerospacial sector in the short and mid term.


Devices/Systems (D3) - MEMS Devices

Session chair: Thomas George, NASA JPL, USA


Nico F. de Rooij, Institute of Microtechnology University of Neuchâtel, Switzerland
Swiss Activities in MNT for Space

Space exploration in the coming century will emphasize on cost effectiveness and highly focused mission objectives. MEMS will be one of the enabling technologies to create small cost, ultra-miniaturized, and functionally focused experiments. Two examples for such miniaturization and successful use of MEMS for space-oriented missions are described.

Experiments with cells in space have shown that important cellular functions are changed in microgravity [1,2]. These findings are of great interest for fundamental research as well as for possible biotechnological applications. To analyze the modification during cell growth, a miniature bioreactor for the cultivation of yeast cells was designed and flown twice (1994 and 1996) aboard Spacelab. The experiment is located in a multi-user facility developed by ESA to host biological experiments.
In view of the complexity of the instrument and the limited dimensions of the container (63x63x85mm), the application of silicon technology to provide pH, temperature and redox sensors as well as a micromachined pump [3] and a flow sensor are of distinct advantage. IMT has designed and fabricated these silicon devices and collaborated with the space biology group of the ETHZ and the company Mecanex to implement them into the bioreactor.

In a completely different field of research, the characterization airborne dust particles present in the Martian atmosphere will help to understand the seasonal variation of the Martian climate and the geological history of the planet. The Mars Environmental Compatibility Assessment Project (MECA) headed by JPL has been designed to analyze dust properties like shape, size distribution and hardness. To be able to assess these properties with nanometer resolution, it uses an Atomic Force Microscope (AFM) [4].
AFM has revealed itself as a reliable tool for characterizing the surface topography of small samples. In principle, a sharp tip mounted on a cantilever is brought into close proximity of the sample surface. The forces acting between the sample and the tip slightly deflect the cantilever. Scanning across the surface while recording this deflection provides a topographic image of the sample.
MECA's AFM consists of a micro-fabricated silicon chip mounted on a voice-coil scanner for controlling X, Y and Z motion. Maximum functionality was transferred to the MEMS device of the AFM:

  • The redundancy of the instrument could be improved by building an array of 8 cantilevers that can be engaged in series
  • The overall size of the device could be drastically reduced by implanting stress sensors directly onto the cantilevers to detect its deflection
  • Diamond tips mounted on selected cantilevers in the array could provide a low-wear material during hard surface interactions.

The entire instrument weights 20 g and has the size of a matchbox. The instrument development was headed by IMT and realized in close collaboration with the company Nanosurf and the Institute of Physics (IFP) of the University of Basel. Unexpected design and management failures during 1999 induced a drastic review of NASA's robotic missions to Mars, causing the cancellation of MECA's flight opportunity. Newly designed mission are scheduled for 2003, 5 and 7.

Walt Merrill, Glennan Microsystems, USA
Harsh Environment Microsystems - The Glennan Microsystems Initiative

The Glennan Microsystems Initiative (GMI) was formed on June 19, 1998, by former NASA Administrator Daniel Goldin, then Ohio Governor George Voinovich, then Case Western Reserve (CWRU) President Agnar Pytte, and Glenn Research Center (GRC) Director, Donald Campbell. As a five-year (1999 -2003) public/private partnership, the Initiative develops, applies and commercializes microsystems technology for harsh environments. This Initiative integrates and augments substantial microsystems resources that currently exist, focuses them on areas of industrial importance and bridges key, critical gaps to commercialization through strategic investments.
The objectives of the Initiative include both technology development and commercialization. Current technology results to be presented include pressure sensors and combustion emission sensor arrays both capable of 500C operation. Also, presented will be the Initiative's program in Silicon Carbide based micromanufacturing.
The commercialization strategy of the Glennan Microsystems Initiative to overcome barriers (existing challenges) is three fold. First, GMI, through its industrially led strategic alliance, implements a research and development program that is market driven and responsive to technology gaps that exist in prospective products. Second, GMI has established an organization that will exploit the strengths of the strategic alliance to put together business development teams to identify and accelerate particular pre-competitive technologies. These business teams will become the kernels of business shells that focus on proprietary product development. Finally, GMI intends to provide the manufacturing infrastructure for development and early stage manufacturing of harsh environment devices. As a result, GMI is investing in Silicon Carbide based processes in both surface and bulk microfabrication as well as electronics and packaging to provide a path for the manufacture of harsh environment devices. In particular we will describe a multi-user silicon carbide (MUSiC) process recently unveiled by the Glennan Initiative and a bulk machining process that is scheduled for deployment in 2003. The MUSiC process is a surface micromachining process, which uses polysilicon carbide as its structural layer material. Similar to well known silicon based multi-user services, such as MUMPS, the MUSiC process is being made available to organizations for fabrication and evaluation of micro devices.

Martyn Snelling, Astrium, UK
Adding Value by Removing Mass

The space industry, like most other industries, is continuously facing the challenge to reduce cost whilst at the same time, to increase performance. Astrium believes that micro system technology with its characteristics of low mass, low power, low volume and the potential for enabling highly integrated systems offers an attractive way to meet this challenge.

However, to fully benefit from the adoption of this technology we must not only consider the micro system hardware, we must also consider micro systems within the overall space system. We must address the computational capability that will allow high levels of autonomy and collaboration and we must change the industrial processes that are presently geared to producing virtually hand built, low volume products - we need intelligent micro systems.

This paper gives an overview of some of the developments Astrium is currently engaged in to acquire an understanding of micro systems and what it can do for our industry. It then discusses how we need to change our approach so that we can work effectively with this new (for us) technology.

Devices/Systems (D4) - MEMS Devices

Session chair: Martyn Snelling, Astrium, UK


Ernest Garcia, Sandia National Laboratories, USA

This paper discusses silicon surface micromachining technology in the context of an optical switching function for a space imaging application. Silicon surface micromachining (SMM) evolved in the early 1980's from experiments conducted at the University of California at Berkeley by a variety of researchers starting with the construction of the first polycrystalline silicon cantilever beam by R. T. Howe and R. S. Muller [ ]. The structure was created by chemically vapor depositing a thin layer of polycrystalline silicon over a silicon dioxide spacer (or sacrificial) layer with subsequent patterning and release. The term surface micromachining usually refers to the construction of thin films via the use of sacrificial layers. In the years that followed advances in the technology lead to the creation of joints [ ], actuators [ , , , ] and a variety of sensors. Possibly the first surface micromachined structure created is credited to H. C. Nathanson who used a patterned gold film to create a cantilever beam, which was used as a resonant gate for a field effect transistor [ ]. Silicon surface micromachining today has evolved greatly; as many as five polysilicon layers can be used to create a myriad of structures and devices. The surface micromachining process can also incorporate other materials in addition to polycrystalline silicon such as metals, nitrides or other materials. Sandia National Laboratories offers a five-level process to external customers at this time (SUMMiTTM V Process). Surface micromachining can also be obtained at a number of other places in North America, Europe and Asia

Feng Songlin, Shanghai Institute of Metallurgy, China
MEMS and Pico-Satellite in Chinese Academic of Science

Gerhard Krotz, EADS-CRC, Germany
Aerospace Applications of Mass Market MEMS Products

Roman Kruzelecky, MPB, Canada
The Application of Thin-film Smart coatings for the Miniaturization of Space Systems

Thin films based on transition metal oxides can exhibit significant changes in their crystallographic structure, and corresponding electrical and optical characteristics, in response to external stimuli such as temperature and electric field. Many of the transition metals such as W, Mn, La, and V, are characterized by partially-filled d-orbitals that contribute to the metallic bonding and electrical conduction. The transition metals can readily form a variety of complexes involving the d-orbitals (two eg and three t2g orbitals). Chemical bonding of the transition metals to various ligands, such as oxygen, can produce an energy splitting, Do, of the d-orbitals into a higher energy eg-orbital pair and a lower energy t2g-orbital triplet due to electrostatic ionic and electron-electron interactions. Depending on the electron occupancy of the d-related orbitals in the complex, the energy splitting of the original transition metal d-orbitals can result in an effective band-gap for optical absorption and conduction, producing insulator-like behaviour. By increasing the effective population of conduction electrons in the complex through optical biasing, temperature or field-effect, a transition to a metallic state can be induced at a critical electron concentration and/or temperature.
The evolution of guided-wave optics and linear detector technology has created new possibilities for the realization of miniature integrated-optic spectrometers for the infrared, such as MPBT's IOSPECTM, with performance characteristics that can rival much larger FT-IR spectrometers. Miniature integrated spectrometers coupled to advanced linear detector arrays can facilitate a significantly smaller and lightweight space payload, with operational characteristics that are more robust with respect to the operating environment. The main performance advantage of FT-IR spectrometers is their large effective input aperture. In dispersive spectrometers such as IOSPEC, higher resolution is obtained using narrower input slits. However, this limits the input optical collection efficiency, reducing the attainable SNR. Using optical coding techniques, the single slit can be replaced by an Ns array of VOn programmable apertures. This can provide up to a Ns1.5 gain in SNR relative to the single-slit spectrometers due to signal multiplexing and data redundancy, providing performance that can surpass much larger FT-IR spectrometers. The compact size and minimal power requirements of these integrated spectrometers allows space deployment in relatively economical small-sat and microsat platforms for atmospheric studies and on planetary rovers for surface exploration. The resulting infrared absorption or reflection spectra can provide chemically-specific identification of the presence of water, minerals, various biochemicals and bacteria.

Devices/Systems (D5) - Precision MEMS Sensors and Gyroscopes

Session chair: : Nezih Mrad, DND / IAR-NRCC, Canada


: Eugenio Giacomazzi, Universita di Roma La Sapienza, Italy
Chemical Microthrusters: Effects of Scaling on Combustion

With the emergence of micro and nanosatellites, recent work has started on chemical microthrusters (e.g., deGroot and Oleson, 1996; Beardsley, 1999; Alexchenko et al., 2000). This work has indicated that simple ("geometric") size reduction of chemical thrusters for micro and nanosatellites is based on the argument that thrust (from ideal 1-D rocket theory) scales with throat area , while weight scales with volume . Thus, shrinking a chemical rocket should raise the ratio, a very attractive trend. However, scaling laws should be considered for all physical effects; in fact Ketsdever and Mueller (1999) and Ketsdever et al. (1999) have examined the effects of viscosity and heat transfer, but not those associated with rocket combustion. The goal of this paper is to show how the effects of miniaturizing rocket engines can be estimated in advance, thus avoiding (costly) disappointment. In particular, the attention is focused on combustion physics, i.e., quenching, flame thickness and turbulence length scales. The results show intrinsic limitations to miniaturizing rocket engines posed by combustion physics, as well as the opportunities it provides: for instance, in taking advantage of unwanted effects (e.g., wall heat transfer) to increase operability and performance.

Diana Hodgins, ETB Codicote Innovation Centre, UK
A solid state gyro, a 3 Axis Accelerometer, and a Pressure sensor Devices and Instruments for Space Applications

European technology for Business Ltd (ETB) is a design company in the UK, specializing in the design of physical MST sensors for a variety of applications. Their core expertise lies in piezo-electric ceramics, resonating devices and Microsystems. This paper describes 3 physical MST sensors that ETB are currently developing with partners, that utilize this core expertise, and would be suitable for certain space applications.

Daniel J. Inman, Eric Ruggiero, Virginia Tech, US
Active Dynamic Analysis and Vibration Control of Gossamer Structures Using Smart Materials

ncreasing costs for space shuttle missions translate to smaller, lighter, and more flexible satellites that maintain or improve current dynamic requirements. This is especially true for optical systems and surfaces. Lightweight, inflatable structures, otherwise known as gossamer structures, are smaller, lighter, and more flexible than current satellite technology. Unfortunately, little research has been performed investigating cost effective and feasible methods of dynamic analysis and control of these structures due to their inherent, non-linear dynamic properties. Gossamer spacecraft have the potential of introducing lenses and membrane arrays in orbit on the order of 25 m in diameter. With such huge structures in space, imaging resolution and communication transmissibility will correspondingly increase in orders of magnitude.

A daunting problem facing gossamer spacecraft is their highly flexible nature. Previous attempts at ground testing have produced only localized deformation of the structure's skin rather than excitation of the global (entire structure's) modes. Unfortunately, the global modes are necessary for model parameter verification. The motivation of this research is to find an effective and repeatable methodology for obtaining the dynamic response characteristics of a flexible, inflatable structure. By obtaining the dynamic response characteristics, a suitable control technique may be developed to effectively control the structure's vibration. Smart materials can be used for both active dynamic analysis as well as active control. In particular, piezoelectric materials, which demonstrate electro-mechanical coupling, are able to sense vibration and consequently can be integrated into a control scheme to reduce such vibration. This research explores the use of NASA Langley Research Center's MFC Actuator as both a sensor and actuator in SISO and MIMO modal analysis techniques. Using smart materials to develop a vibration analysis and control algorithm for a gossamer space structure will fulfill the current requirements of space satellite systems. Smart materials will help spawn the next generation of space satellite technology.

Devices/Systems (D6) - MEMS Devices

Session chair: : Frank Foran, CSA, Canada


Giulio Manzoni, Mechatronic GmbH, Austria
Austrian-Italian Micropropulsion R&D for Nanosatellites

An experimental setup for testing in space the preliminary realization of a micropropulsion system is under development by Mechatronic and INFM. The experiment will be performed on-board the microsatellite UNISAT-2, in the framework of a cooperation between Università di Roma "La Sapienza",Mechatronic and INFM. The main goal of the experiment is to have a preliminary assessment of the microthruster performance in orbit. The thruster configuration for the UNISAT-2 experiment is cold-gas, using pressurized nitrogen (N2). The micro convergent-divergent nozzles, obtained by Microlitography and Reactive Ion Etching from 500µm thickness silicon wafer, have a throat area of about 300µm 2 through which the pressurized gas flow is accelerated. Ground tests have been conducted to evaluate the microthruster performance, showing that the maximum thrust is in the order of 500 µN. The silicon chips have been bounded to a glass support and integrated with microvalves, microsensors and electronic control system desinged and produced by Mechatronic. The whole micropropulsion experiment has been integrated on the payload bay of UNISAT-2 in order to have two pairs of microthrusters mounted with their thrust direction orthogonal to the spin-axis of the spacecraft, and to be used to perform spin-up/spin-down maneuvers. Measuring the satellite spin rate variation, after thruster activation, the average thrust is evaluated.

Daniel Gratton, CSA, Canada
MEMS Development Programs at the CSA

Christiaan Van Hoof, IMEC, Belgium
Engineering and Flight model development at IMEC

The presentation gives an overview of key ongoing space microelectronics activities at IMEC in the areas of technology, flight hardware development and design. Technology development concerns MEMS switches, concentrator solar cells and infrared imagers. Flight model development concerns integrated radiation-tolerant CMOS image sensors, cryogenic sensor readout electronics and advanced sensor readout circuits. Design related activities concern an FPGA implementation of a wavelet based flexible compression engine, a generic Turbo codec ASIC implementation as well as the realisation of a radiation tolerant design library for commercial CMOS based ASIC technologies.

Devices/Systems (D7) - Nano Devices

Session chair: : Tim Harper, European NanoBusiness Association, Spain


Volker Klocke, Klocke Nanotechnik, Germany
Nanorobotics for the International Space Station / Nanomotors for RF technology

In the presentation actuators and Nanorobotics will be described including possible aerospace applications. As basic element the Nanomotor delivers atomic resolution at up to 70 mm of stroke. It is the smallest and most precise linear motor worldwide and offers a set of advantages for space applications. The Nanomotor is:
· Ultra high vacuum compatible
· Low temperature compatible down to 4 Kelvin, even inside of liquid He
· It needs only low voltages
· It can hold its position without power supply
· An integrated sliding clutch allows force limitations
· The Nanomotor can act as "Micro-jackhammer" to process material.
These properties are an important help for a space qualification.

Besides this small linear actuator, positioners with many degrees of freedom, manipulators and complete Nanorobotics systems will be presented.

A wide range of high precision applications can be realized like high-frequency tuners for satellites, Mini-spectrometers, devices to move objects like a shutter (e.g. Sojourner Rover), actuators for mini-satellites, or a complete handling station for the International Space Station. For the realization of experiments in the International Space Station it is often necessary to handle objects for preparation or storage. But the time of the astronauts is expensive. The Nanorobotics system from Klocke Nanotechnik can solve these tasks by Joystick control, even from the earth if necessary.

The Nanorobotics series builds a bridge between nanotechnology and the classical mechanical engineering. These products combine the advantages of both technologies: the backlash free movement with resolution of better 10 nanometer and the capability of kilograms of load at centimeters stroke. This series of the smallest and most precise positioning modules offers plenty degrees of freedom in smallest volume for microassembly, interconnection technology, analysis and reliability testing. The repeatability of classical assembly lines is limited to a few microns. The Nanorobotics modules allow absolute positioning within 50 Nanometers. These properties are good enough even for future applications that cannot be predicted now, an important feature for a longtime investment.

A handling system made with Nanorobotics can transport objects with diameters between some 10 microns and some 10 Millimeter. The system can be controlled by Joystick - in combination with cameras even from the earth. Integrated position sensors allow the automatic usage. For live science the transport of smallest drops can be realized, gravity has no influence.

Astrium, Germany
MST technology roadmap and MST in-orbit verification 2000-200

Devices/Systems (D8) - Nano Materials

Session chair: : Prakash Patnaik, IAR-NRC, Canada


Simon Brown, University of Canterbury, New Zealand
Nanowires and Control of Nanoparticle Deposition Via Percolation

Random deposition of conducting nanoparticles on a flat two dimensional (2D) substrate leads to the formation of a conducting path at the percolation threshold. In sufficiently small systems significant finite size effects are expected. However, in the 2D square systems that are usually studied, the random deposition means that the main effect of small system sizes is that stochastic fluctuations become increasingly large.

We have performed experiments and simulations on rectangular 2D nanoparticle films with nanoscale overall dimensions. [1] The sample geometry is chosen to limit stochastic fluctuations in the film's properties. In the experiments bismuth nanoparticles with mean diameters in the range 20-60nm are deposited between contacts with separations down to 200nm. When the maximum number of clusters that fit between the contacts is ~5 we are able to show that a conducting nanowire, which is automatically connected to electrical contacts, is formed close to the percolation threshold. Percolation theory describes the experimental onset of conduction well: there is good agreement between predicted and measured values of the power law exponent for the correlation length.

We have also performed extensive measurements of the conductivity of samples with a wide range of nanoparticle densities. Dramatic steps in the conductivity are observed while ramping the applied bias, due to electrically driven changes in the connections between nanoparticles. Field emission SEM measurements have been performed to assist the interpretation of the conductivity data.

Finally we show that our understanding of percolation in these devices can be used to provide a convenient method of local, real-time, sub-monolayer control of particle deposition.

Michel Meunier, Ecole Polytechnique Montreal
Laser Micro-Nano Engineering of Materials

Barry Stansfield, INRS, Canada
Carbon Nanotubes

Devices/Systems (D9) - Nano Electronics

Session chair: :Carles Ferrer, CNM, Spain


Hatem Mehrez, Harvard University, USA
Theoretical Modeling of Electronic Transport Through Nano-Structure Devices

Electronic transport through nano-devices is quite different from micro-systems due to the absence of electronic scattering in such small structures. This results in Ballistic, rather than diffusive transport in these systems. In addition to this, the small number of atoms in these devices, enhances environmental effects and becomes more difficult to interpret experimental data. Hence, investigations from first principles are required. Recently, new approaches, within Local Density Approximation, have been developed to investigate current-voltage (I-V) characteristics of nano device systems. Using such a model, we have analyzed non-linear I-V characteristics of Gold nano-wires and we have found qualitative as well as quantitative agreement with the recent experimental measurements. Our investigations show that clean Gold nano-wires exhibit linear behavior, whereas non-linearity emerges due to impurity effects at the contact. In this talk we will give some details of the recent experimental data, briefly explain the theoretical model, show our numerical results and compare them with the experiment. Another important effect that emerges in such systems, is electron-phonon coupling. Due to the low atomic coordination number in such devices, adding an extra electron to the system results in atomic and electronic eigen-states rearrangement; and hence different electronic transport while compared with the static structure. This usually decreases the electronic gap of semi-conductor nano-devices and electronic transport is polaronic assisted. However, to investigate such a phenomenon requires dealing with a large phonon basis set. We have recently developed an approach to partially overcome this problem. We will describe our method and results within Su-Schrieffer-Heeger model of one-dimensional chain. Our simulations show that polaron assisted electronic transport enhances the zero bias conductance of semi-conductor chains, especially longer ones where the pure electronic transport is largely reduced.

Devices/Systems (D10) - Photonics and Bio Nanotechnology

Session chair: :Asoke Ghosh, CSA, Canada


Carole Rossi-Bazin, LAAS Laboratory, France
The Development of Solid propellant uRockets forSpace Applications

Scientists and space community agree that Microsystems technology will revolutionize space industry. The benefits would be a reduction of parts because of a better integration of each component, a decrease of material variability and a better reliability. Of course, the resulting benefits would be a mass reduction and a lower fabrication cost. In this tendency, every subsystems of the satellite may be re-envisioned and miniaturized. Propulsion are a key point in the miniaturization of spacecrafts because micro and nanospacecrafts would need very small (below the Newton) and very accurate force to realize the stabilization, the pointing and the station keeping.

This paper presents a solid propellant microrocket devices for micropropulsion needs. The concept is based on the high rate combustion of one single propellant stored in a combustion chamber. The lack of restart ability is compensated by the fabrication of arrays of microrockets. The gas generated by the combustion of the propellant is accelerated in a nozzle thus delivering a thrust. One single rocket consists of a stack of 3 parts of silicon:
1. A silicon micromachined igniter with a polysilicon resistor patterned onto a very thin dielectric membrane.
2. A propellant chamber.
3. A diverging part wafer can be added on top of the structure if necessary.

Uri Sagman, C Sixty Inc., Canada
Nanomedicine: Fullerene and Nanotube Biology

The direct application of nanoscale materials to biological targets is now yielding promising applications in medicine.[1] This talk will review the field of fullerene and carbon nanotube biology, as well as describe current applications of fullerene derivatives in biology and medicine.[2]

The flexible chemical reactivity of fullerene-C60 has already resulted in the synthesis of numerous fullerene compounds that are now available for study. In addition, at 7.2 A in diameter, C60 is similar in size to steroid hormones or peptide alpha-helices and thus fullerene compounds are ideal molecules to serve as ligands for enzymes and receptors.

Other fundamental physical and chemical properties of fullerenes govern how they may be adapted for biological use. While fullerene-C60 itself shows no solubility in water, many fullerene compounds can be very water soluble. Such derivatives of C60 contain polar side chains and, as a general rule, the greater the number of polar groups the greater the water solubility. In order to maximize the chances of advantageous adsorption and distribution properties of bioactive compounds, it is generally accepted that there are certain desirable ranges of lipophilicity and several fullerene compounds have already been reported that are in favorable therapeutic ranges

Numerous useful fullerene-based therapeutics have already been developed, including anti-viral agents, neuroprotective agents, and anti-cancer drugs, as well as biosensors for diagnostic applications. The use of these fullerene-based nanoscale products for pharmaceuticals and for medical device applications will be discussed, including the advance of fullerene-based therapeutics to human clinical trials


(D11) - Micro Machined Silicon Sensors and Actuators for Space Applications

Session chair: Daniel Inman and Eric Ruggiero, Virginia Tech


Alex Dommann, Interstate University of Applied Science, Switzerland
Accurate Microscopic Method to Investigate the Aging of Micromachined Silicon Actuators

We compare the strain and dislocation density induced by thermally grown silicon dioxide on silicon wafers with those in a microfabricated thermal bimorphous beam actuator as well as the influence of aging on these parameters. A high-resolution x-ray diffractometer allows measuring the strain of a crystal. This is an accurate, non-destructive microscopic method applied in the field of MEMS to obtain quantified results on the crystalline disorder. Aging of a micromachined silicon actuator results in a change of the strain profile. The method is applied to a bimorphous Si/Al actuator on which hysteresis was observed. It is shown, that thin film thermal silicon dioxide stresses the silicon much less then aluminum, which was found to cause the observed aging of the bimorphous structure. By removing the aluminum layer, almost complete relaxation could be observed.

Farrokh Ayazi, Georgia Tech, USA
Enabling Technology (HARPSS) Which Can be Used to Make Both High Precision Gyroscopes and MEMS Resonators.

This talk will present the applications of the HARPSS process to integrated RF and sensory micro-electro-mechanical systems. HARPSS (High Aspect-Ratio Poly and Single-Crystal Silicon) is an all-silicon MEMS technology that is capable of producing self-aligned nanometer-in-size vertical airgaps in between 1-10's of microns thick high quality factor silicon structures. This technology provides features required for implementation of high-precision inertial sensors (accelerometers and vibratory gyroscopes) as well as high frequency electrostatic micromechanical resonators for RF applications. High-Q MEMS resonators are prime candidates to replace frequency references and bandpass filters in future integrated RF transceiver systems. The all-silicon feature of the HARPSS technology improves long term stability and temperature sensitivity while fabrication of large area, vertical capacitors with sub-micron gap spacing will increase the sensitivity by orders of magnitude. The latest results on application of this technology to RF and sensory MEMS will be presented in this talk.

Last update - May 28, 2003