Die Nanotechnologie wird neben der Biotechnologie als eine der Schlüsseltechnologien des 21. Jahrhunderts mit weit reichenden Auswirkungen auf die Wissenschaft, industrielle Entwicklung, und Entstehung neuer Produkte und daher höchst bedeutsam für eine erfolgreiche volkswirtschaftliche Entwicklung der kommenden Jahrzehnte angesehen. Gegenstand der Nanotechnologie ist die Herstellung, Untersuchung und Anwendung von Strukturen, molekularen Materialien, inneren Grenzflächen und Oberflächen mit kritischen Dimensionen oder Fertigungstoleranzen von einigen wenigen bis ca. hundert Nanometern. In den wichtigsten Industriesparten wird in zunehmendem Maße erkannt, dass die Kontrolle der strukturellen und funktionellen Eigenschaften neuartiger Materialien auf der Nanometer-Skala der Schlüssel für technologischen Fortschritt und neue Produkte für die Eroberung neuer Märkte darstellt. Voraussetzung hierfür sind fachübergreifende Kenntnisse der Prinzipien und Methoden der Nanotechnologie, die in den klassischen naturwissenschaftlich-technischen Disziplinen wie Festkörperphysik, Biologie und Chemie ihren Ausgang finden. Aus diesem Grund versteht sich die Nanotechnologie als eine im hohen Maße interdisziplinäre Wissenschaft die ein über die genanten Einzeldisziplinen hinausgehendes, vernetztes Denken und Arbeiten erfordert. Im Rahmen des Arbeitskreises soll über verschiedene Aspekte der Nanotechnologie mit Vertretern aus Wissenschaft und Wirtschaft diskutiert werden.
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Eduard ARZT
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Ordentlicher Professor und Geschäftsführender Direktor des Instituts für Metallkunde an der Universität Stuttgart, gleichzeitig Mitglied des Leitungskollegiums und stv. Geschäftsführender Direktor des Max-Planck-Instituts für Metallforschung, Stuttgart |
Abstract
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Nanomechanics of biological and artificial attachment devices
Mechanics rules biology: living systems rely for their survival, to a large extent, on mechanical functions. This is true on the level of cells, which adhere to substrates in controlled and dynamic ways and are known to communicate by mechanical means. It also applies, on the molecular level, to folding and unfolding processes, which may be viewed and studied as mechanical events. Another important case is the adhesion of various animals, e.g. beetles, flies, spiders, and geckos, to surfaces during locomotion. These animals exhibit fibrous attachment organs which are finely-structured down to micron and sub-micron dimensions. The micro and nanomechanisms of adhesion in these animals are still under debate.
We have in a broad interdisciplinary study investigated the structure and function of these contact elements on the micro and nano level by microscopical and nanomechanical techniques. Local mechanical properties and adhesion forces were measured by novel test methods and compared with predictions based on theoretical contact mechanics. Structure, size and shape of the contact elements are found to play important roles; in particular the principle of "contact splitting" has been identified: finer contact elements (down to sub-micron level) produce larger contact forces in heavier animals. The insight gained in studying biological systems can be transferred to the development of optimized artificial attachment devices. From our findings, the desired mechanical parameters of attachment structures can conveniently be delineated in newly-developed adhesion design maps. Based on these investigations, a clearer strategy for producing optimum bio-inspired attachment structures is beginning to emerge.
The possible impact of these studies is manifold: Controlled adhesion is important in everyday life and in technological applications, e.g. in sticky tapes, car tires, wafer bonding or micro-objects in the packaging industry. Intelligent adhesion which is reversible and does not lead to alterations of the surfaces involved (as in conventional adhesives) is potentially of great pratical interest. Largely through bio-inspiration and trial and error, first prototypes of such artificial contact systems have recently been designed in the laboratory.
This research direction has, under the name of biomimetics or bionics , gained much momentum and popularity in recent years. Learning from nature is however not a new concept. Especially since Leonardo da Vinci, mankind has profited, consciously or subconsciously, from close observation and exploitation of natural processes. Biomimetic design can however not be based on merely copying natural solutions; a thorough understanding of biological principles is required to find technical solutions specifically adapted to a particular application. Only recently has it become possible to characterize and explain the mechanical performance of bio-mechanical device on the micron and sub-micron scale. The case of the gecko has taught us that miniaturization down to the nano-scale has far-reaching consequences for the macroscopic properties even in natural systems.
This talk describes and summarizes our recent investigations into the nano and micromechanics of biological attachment devices. First, the relevant concepts of contact theory, especially concerning the size and shape dependence of van der Waals contact forces, are developed. Miniaturization down into the nanometer range is an essential strategy but there are principal limitations which can be conveniently described by the new adhesion design maps . Recent micromechanical measurements of adhesion forces for single gecko spatulae and of mechanical properties of biological adhesion systems are then described. For this, novel test techniques have been developed which allow testing e.g. inside a focussed ion beam system. Overall, our study underscores the need to understand the several variables involved in forming an adhesive contact system for repetitive, reversible use. The optimum contact requires a balance of contact element size, shape and material, all of which are dependent on one another. The transfer of these principles into possible technical applications is currently underway.
Acknowledgments
This paper describes the results of several studies performed at the Max Planck Institute for Metals Research. They would not be possible without the biological expertise of my colleagues S. Gorb, J. Schuppert, and S. Niederegger. Materials scientists involved are R. Spolenak, G. Huber, U. Wegst, S. Orso, C. Eberl, and H. Pfaff. Fruitful discussions on theoretical aspects with H. Gao are also greatly appreciated.
Literature:
E. Arzt, S. Gorb and R. Spolenak, From micro to nano contacts in biological attachment devices, Proc. Nat. Acad. Sci. USA 100:19, 10603 (2003)
G. Huber, S. Gorb, R. Spolenak and E. Arzt, Resolving the nanoscale adhesion of individual gecko spatulae by atomic force microscopy, Biol. Lett. , Royal Society, 2005
R. Spolenak, S. Gorb and E. Arzt, Adhesion design maps for bio-inspired attachment systems, Acta Biomaterialia 1, 5-14 (2005)
R. Spolenak, S. Gorb, H. Gao and E. Arzt, Effects of contact shape on the scaling of biological attachments, Proc. Roy. Soc. A, in press (2005) |
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Hubert BRÜCKL
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Head, Business Unit "Nano Systems"', Department Health & Environment, AIT Austrian Institute of Technology GmbH, Vienna |
Abstract
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Magnetic nanostructures for sensor and memory applications:
Status quo and trends
Magnetic and magnetic related sensor research and development has been undergoing a quiet revolution, promising to have significant impact on a broad range of applications relating to security, health care, the environment, energy, food safety, nondestructive failure analysis and manufacturing. The advanced biological, chemical and materials research is also bringing new bloods for the area, including the design of functional nano- and meso-scale complex structures.
In contrast to the sensors, magnetic memory development has gained relatively much publicity. Magnetic hard disk heads and MRAM (magnetic random access memory) are prominent examples of magnetic nanoscale objects which crossed the river from basic research to device application in only a few years. Despite of the clear intention of the industry to introduce more of the projected devices the next year(s), basic mechanisms are still unclear, like the contribution of scattering at defects, magnons and phonons to the tunnel current or the magnetic switching behavior of elements in the size range of 100 nm. Nevertheless, there are much more possibilities ahead in the area of magnetoelectronics and spintronics.
A consequent development - after memory - is the implementation of magnetic tunnel junctions in logic devices. Magnetic logic devices are announced to be another lucrative market by argumentations resting on the same advantages as MRAM technology. The non-volatile character allows a reprogrammable and reconfigurable logic. Especially tempting is the fact that memory and logic are then based on the same technology platform. This opens the unique opportunity to build up a unified system on a single chip. Furthermore, magnetic tunnel junctions are promising sensors for magnetoresistive biochips, which are capable to detect even single molecules by means of functionalized magnetic particles. These magnetic particles are used as labels of biomolecules like DNA and can be detected by magnetoresistive sensors.
This contribution addresses novel ideas and open basic questions in selected areas of magnetic nanoscale devices. This includes the development of magnetic logic, System-on-Chip, biochips, pacemakers, magneto-acoustic sensors and pressure-sensitive devices, for example. |
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Helmut LIST
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Chairman and Chief Executive Officer, AVL List GmbH, Graz |
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Anforderungen an die Nanotechnologie in Antriebssystemen für nachhaltige Mobilität
Die Anwendung der Nanotechnologie stellt bei der Entwicklung zukünftiger Antriebssysteme eine besondere Chance dar. Sie wird in Zukunft helfen, den Kraftstoffverbrauch, die Schadstoffemissionen und das Geräusch zu senken.
Nanotechnologie als Architektur kleinster Strukturen bietet Potentiale für Themen wie Reibungsverminderung, einen effizienteren Verbrennungsprozess und alternative Antriebssysteme:
Reibung wird durch Grenzflächenphänomene, also molekulare Wechselwirkungen, bestimmt, die Effizienz des Verbrennunsprozesses durch Präzision im Mikrometerbereich, die dafür notwendige Aktorik und Sensorik ist ohne Engineering im Nanobereich nicht darstellbar.
Als alternative Antriebstechnologie steht die Brennstoffzelle im Fokus: Deren Leistungsfähigkeit wird durch die Wechselwirkung einer Membran mit umgebenden Medien bestimmt, die notwendigen Diffussions- und Adsorptionseigenschaften werden durch Veränderung von Molekülkettenteilen gestaltet.
Somit kann in mehrfacher Weise die Umweltverträglichkeit und Funktionsfähigkeit von Fahrzeugen durch den Einsatz der Nanotechnologie deutlich verbessert werden. Weiters ist zu erwarten, dass hierdurch Materialverbrauch und Kosten reduzieren werden. Selbstverständlich müssen weitere Aspekte wie Herstellprozesse, Dauerhaltbarkeit, u.a. gelöst werden, bevor die Nanotechnologie in der Produktion von Antriebssystemen mittelfristig zum Einsatz kommt.
Dazu ist es notwendig, dass frühzeitig die Anforderungen der Industrie an die Nanotechnologie definiert und gemeinsam mit der orientierten Grundlagenforschung kooperative F&TE Initiativen gestartet werden. |
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Friedrich B. PRINZ
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Finmeccanica Professor and Robert Bosch Chair of Mechanical Engineering, Stanford University, Stanford |
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Nano Scale Technologies for Future Power Generators
The unparalleled performance of today's computer technology was enabled by revolutionary changes in micro fabrication technology. In particular, the seemingly endless down scaling of characteristic feature dimensions of electronic components from a few microns down to a few tenth of a micron allowed the realization of processors with operational frequencies ranging from the megahertz to the gigahertz frequency regime. During the last decade or so, design ideas and fabrication methods from the world of micro electronics have started to inspire other disciplines. As an example consider the field of MEMS (Micro Electronic Mechanical Systems). MEMS takes advantage of existing micro electronic fabrication techniques for creating miniature devices such as sensors, actuators, and, in the future, power generators. While the benefits of down scaling in microelectronics are obvious - smaller processors operate at faster speeds - the ramifications of down scaled mechanical devices are less apparent.
This talk will focus on the opportunities of MEMS technologies for the creation of next generation power devices such as fuel cells. In particular, we shall discuss recent results on the benefits of thin film membranes with a thickness of a few hundred atomic layers embedded in a fuel cell structure. Thinner membranes contribute towards improved power efficiency and comparatively lower operating temperature.
Finally, we will draw analogies between fuel cells and the way biological cells power themselves. The possibility exists that nanoscale electrodes may be used to directly extract electrical energy from organelles separated by thin biological membranes. |
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Klaus VON KLITZING
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Direktor und Wissenschaftliches Mitglied, Max-Planck-Institut für Festkörperforschung, Stuttgart |
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Einstein s Nobel Prize and Modern Nanoelectronic
The Einstein Year 2005 marks the centenary of Einstein s three publications which changed the way we understand our world. His paper about the photoelectric effect, which formed the basis for his Nobel Prize in Physics 1921, was the starting point for discussions about the wave-particle duality in nature and the development of quantum mechanics.
Today, nanoelectronics is the ideal playground to investigate and to apply in a controlled way quantum phenomena and to prove different Gedankenexperimente discussed by Einstein.
It is generally accepted, that the scaling law for the miniaturization of microelectronic devices breaks down if the wave nature and the discrete charge of electrons or tunneling phenomena dominate the electronic properties. These quantum phenomena do not mark the end in the miniaturization of devices but open the possibility to create new devices with new functions where for example the energy quantization of electrons in confined structures, tunnel phenomena through barriers and single electron charging of small islands play an important role. The roadmap in nanoelectronics mention new devices like resonant tunneling diode, single electron transistor, quantum cellular automata or nanotube devices. Up to now it is not clear, whether the top-down process in miniaturization will be successful in nanoelectronics or whether molecular systems and self organized structures will be combined with standard CMOS technology.
Carbon nanotubes seem to be an interesting building block for applications in nanoelectronics and some new developments in this field will be presented. The main part of the talk will discuss the most important technologies for the preparation of semiconductor nanostructures and the new properties of these devices if quantum phenomena become important |
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Emil J. W. LIST
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Leiter des Christian-Doppler-Laboratoriums "Advanced Functional Materials", Technische Universität Graz |
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Chair |
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The Impact of Nanotechnology on Every day Life
The scope of nanotechnology is vast but in technical terms it is most easily summarised as the technology of processes, structures and devices that operate on a scale of between one ten millionth of a millimetre and one ten thousandth of a millimetre. Such a technical description is easily understood by scientist and technical staff but to reach broad acceptance there is a need to translate the terms to how this will influence our every day life in the future. Based on the working group contributions the participants will discuss important issues of general concern in a podium discussion taking place after the individual contributions. |
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