Einfluss der Morphologie von elektroaktiven Polymeren auf den Interkalationsprozess

Die Anwendung von Kohlenstoffnanoröhrchen (CNT) und ionischen Flüssigkeiten in auf Polymeren basierenden Verbundwerkstoffen ist seit langer Zeit Gegenstand von intensiven Forschungen und es besteht ein großes wissenschaftliches Interesse an deren Eigenschaften. Bis jetzt waren die Geometrie und Morphologie bestimmende Faktoren für die Ausschlageigenschaften von Aktoren. Lange, dünne Aktoren zum Beispiel generieren einen größeren Ausschlag, während ringförmige mehr Kraft haben und sehr dünne sich bei einer viel höheren Frequenz bewegen. Des Weiteren wurde die Verbindung von vielen Aktoren zu Stapeln mit dem Ziel ihre Eigenschaften (Kraft, Ausschlag, Geschwindigkeit) zu vervielfachen untersucht. Zudem wurde der bestimmende Parameter der Interaktion zwischen Kontaktelektroden und multiplen Aktorsystemen zuletzt oft vernachlässigt. Um die verschiedenen Variablen zu charakterisieren und zu optimieren, wurde systematisch ein aus der konstruktionstechnischen Sichtweise funktionell arbeitendes System einwickelt, welches reale Situationen nachahmen soll. Zusätzlich werden die genannten Hauptparameter untersucht. Die fundamentalen Faktoren der Geometrie, des Stapelns und des Elektrodendesigns werden sich als entscheidende Faktoren bei der Betrachtung von auf CNT-Polymeren basierenden Aktoren in allen funktionellen Modellen herausstellen. Das finale Ziel ist die Unterstreichung der konstruktionsspezifischen Faktoren zur Erreichung des optimalen Verhaltens bei der Aktuation. Es wird sich zeigen, dass das Verbinden von wissenschaftlichen Erkenntnissen und konstruktionstechnische Grundprinzipien den Einsatz von auf CNT-Polymeren basierenden Aktoren in derzeitigen und zukünftigen Anwendungen ermöglichen wird

Printed pumps based on CNT electrodes

Automated dosing of small amounts of liquids normally involves quite large pipettes and motors for pipette actuation. Miniaturized pumps and pipettes can enable new areas, in which micro dosing is demanded and could be particularly beneficial in the field of medical or (bio-) chemical applications. The approach was the direct integration of a bending CNT actuator into a 30-printed pump design, which enables a frictionless induction of movement onto a liquid. Printing a number of parts that each have a separate function or task and putting these parts tagether to an integrated module has proven to be beneficial in testing, evaluating and optimizing the performance of the micro-pump. Additive Manufacturing offers multiple possibilities in combination with nanomaterials. lncreasing material properties is one option as weil as directly including functionalized materials. The ability to print every single required partout of the same material enables manufacturing cost reduction, speed of process and unique design flexibility. The presentation will show some chances and possibilities coming out of this combination

Electroactive Polymers: How to Link Science and Industry: Symposium, 21. April 2015, Stuttgart, Fraunhofer IPA

During the last decade enormous growth in basic research and the start of commercial products has led to a worldwide reaction to electroactive polymers (EAP) technology and their potential. EAP are essential to satisfy the constantly growing demand for sensors, actuators and energy storage systems due to industry 4.0. On behalf of Fraunhofer IPA and AIST Kansai, the largest Japanese institute of applied sciences, we would like to cordially invite you to attend and contribute to the symposium "Electroactive Polymers: how to link science and industry" at the Commundo Conference Hotel Stuttgart, Germany. Talks from top-level researchers in the field of EAP are awaiting you. This event is intended to provide a platform for exchange on how the industry and research can symbiotically work together, trigger dialogue, provide enriching experience and offer opportunities for co-operation

Plasma spheroidised metals for additive manufacturing

Metal and ceramic powders are the basis for many technical and industrial processes and applications, such as powder metallurgy, thermal spraying, electronics and catalysis. Nevertheless, there is still a need for further developments, because the powdery raw materials eventually determine the properties of final products and may be the cause of the problems in the processing of these: Impurities or corrosion processes at the powder production (e.g. by the grinding processes) can have a disadvantageous effect or the particle shape leads to a greater abrasion or a rough coating texture. At the same time market requirements are changing more and more quickly and frequently. To be able to react to this, manufacturers need flexible, fast solutions for development, production and quality assurance. Thereby, the high melting point of metals such as tungsten or titanium or technical ceramics (tungsten carbide), which are important for hard alloys, is an additional challenge

Carbon nanotube - reinforced copper matrix composites produced by melt stirring

Due to their geometry and extraordinary mechanical properties, carbon nanotubes have been envisioned as promising enhancements for metal matrix composites. In this article, we report on our melt stirring approach for incorporation of carbon nanotubes into a copper alloy matrix and on the experimental results obtained by assessing the material properties. The existence of carbon nanotubes in the copper matrix after processing was proven by Raman analysis. We found that the small amounts of carbon nanotubes (0.1 wt%) in the composites influenced mechanical and abrasive wear properties

Titanium (TiO2) coated nano-carbons in an aluminium matrix for weight reduction applications: Poster presented at Euro LightMAT 2013, Magnesium, Aluminium, Titanium. Science and Technology. International Congress on Light Materials, 3-5 September 2013, Bremen

One of the most urgent needs in automotive industry is the reduction of weight. Light cars produce less CO2, use less energy, are easy to brake or accelerate and show a much better driving performance than heavier cars. In the case of electro vehicles, weight reduction is vital to extend the driving range - thus lightweight material is a key for modern mobility. While metal alloys already reached their technical limits, carbon fibre based car parts are still not mass producible today. This situation leads to a gap which can be filled by using carbon nanotubes (CNT) reinforced alloys to provide high-performance alloys for the mobility of tomorrow. By modifying the nano carbon (NC) surface through coating (via CVD- or Sol Gel-procedure) it is possible to further increase the interfacial bonding as well a protecting the NC from detrimental composite manufacturing processing. The metal-oxide coatings applied via this two procedures differ in structure and degree of coating. Although a full coating of the NC has not been reached so far, results in achieved in processing are encouraging. The advantages and disadvantages of both procedures for large scale application are discussed. Fraunhofer IPA has been conducting research and development of metal matrix composites (MMC) with such nano-carbon materials. The outstanding thermal, electrical, and mechanical properties of nano-carbons are applied to a wide range of applications. By varying the manufacturing process it is possible to tailor the physical, thermal or electrical properties of the material. The result is an aluminium alloy exhibiting vastly superior reproducible physical properties (tensile and ultimate strength increased by 100% and 180% respectively, Impact strength over 270%, E module increase of 30% (ductility kept) and increase of 80% in damping ratio) produced by an economically feasible process (up scalable)

Controlled fabrication and system integration of CNT-based ionic actuators - example: Liquid handling for biomedical applications: Poster presented at EuroEAP 2016, International Conference on Electromechanically Active Polymer (EAP) Transducers & Artificial Muscles, 14-15 June 2016, Helsingør, Denmark

CNT-based ionic EAPs present a unique and promising actuator material for a variety of potential applications, because they offer a safe way of transforming low-voltage electrical energy into mechanical work. However, due to rather complex manufacturing techniques and low electromechanical efficiencies only very few applications for CNT actuators have been in the focus of R&D activities. Multiple variations of materials, dispersing methods and assembly processes have been adopted throughout the years with the aim to optimize not only performance (stress, strain and reaction rate), but also reproducibility of actuators. Current state of the art production methods are still in the domain of lab scale. The growing interest from multiple industry sectors has now created the need for the scientific community to come together and develop new or adapt existing manufacturing routes capable of mass production for the expected demand of the future. A focus on biomedical applications, fabrication control and system integration of the actuators to enable increased reproducible performance will be the aim of this work. We explore topics from additive manufacturing technology enabling ease of system integration to the influence of electronic contacts on the reproducibility of actuator performance

Experimental investigations on carbon nanotube actuators defining the operation point and its standard deviation

Carbon nanotube (CNT) actuators have been extensively investigated from the perspective of materials, their composition, and system construction as well as from three main performance features, which are displacement, force and velocity. However, up till now none of the CNT actuators have reached the stage of implementation into products. It is due to the fact that even though from the point of view of performance each property can reach satisfactory values, their combination is much more difficult, as they are not proportional. This relation of properties motivated the work to test and investigate currently available CNT-polymer actuators to define their operation point. Under this term one should understand a performance of actuator where displacement, force and velocity do not affect each other. In other words, any change in one of the properties will adversely affect at least one of the remaining ones. The measurements are performed in out-of-plane mode on 2 cm diameter samples in low frequency range (0.01 - 1 Hz) under application of low voltage (2 V). Measurement curves of three main actuator properties are plotted together against the frequency resulting in operation point as the intersection point of those curves. Additionally the deviations in actuator performance are assessed to reflect the actuators' reproducibility and their production process stability by means of standard deviation. Knowledge about the relation between actuator properties and the value of operation point will facilitate evaluation of the existing CNT actuator against its potential applications

Development and investigations on multiple carbon nanotube actuator systems for magnified performance and minimization of performance losses

Carbon nanotubes (CNT), as active materials have shown a great potential for industrial applications especially in medical technology due to their high strain, low driving voltage, light weight and flexibility. The driving principle of CNT actuator operation is electrochemical double layer charging, which necessities the presence of electrolyte. This represents a major set back with respect to possible applications. This has been overcome by the development of so called "dry" actuators. These are based on CNT -polymer composites, where the electrolyte is encapsulated within the polymer matrix. Such composites have been build up and used as three layer actuators, where two outer layers containing CNTs are considered as active layers and are separated by the middle layer, separator, which serves as electrical isolator as weH as an ion reservoir. CNT-polymer actuators, although appropriate from the performance point of view, have not yet reached the medical market due to the unknown interactions between CNTs and living organisms. However, the achievements obtained in the development of CNT actuators highlight the potential for applications in other market sectors. CNT actuators could be used as positioning systems, valves and pumps, switches and brakes. In order to have the possibility to offer CNT actuators to a broader spectrum of industries, further developments must be carried out. Within this work multiple actuator systems were developed with a target of multiplication of actuator performance by combining several of them together. Such developments demonstrated the possibility of symbiotic cooperation between integrated CNT actuators and mechanical systems to work as one. Multiple actuator systems were tested in respect to their displacement and force generation as the primary characteristic features of any actuator. Those systems were experimentally measured in an out-of-plane mode of operation at low frequency ranges « 1 Hz) and under Iow driving voltages (2 Volt). The first results indicated that there is no direct proportionality between the multiple actuator system performance and the number of actuators involved. For this reason experimental investigations were undertaken in order to define the performance of actuator systems and minimize the losses, which may occur due to the unsuitable amount of actuators used in a stack. Furthermore, in order to minimize the losses in the performance of actuator system extensive development work was carried out on the optimum design and implementation of electrodes within the system. In parallel various materials where tested in a search for best electrode, as it was observed that they can greatly influence the operating characteristics. The investigations carried out within this research are targeted in finding the optimum design for multiple actuator systems with improved displacement and exertion of force

Integration of CNT-based actuators for bio-medical applications: Example printed circuit board CNT actuator pipette

In order to strengthen the position of CNT actuator technology and fasten the transfer of scientific results into application development and market introduction scientific institutes AIST Kansai and Fraunhofer IPA cooperated in the field of electroactive polymers. Automated dosing of small amounts of liquids normally involves quite large pipettes and motors for pipette actuation. Miniaturized pipettes can enable new areas, in which micro dosing is demanded and could be particularly beneficial in the field of medical or (bio-) chemical applications. The approach was the direct integration of a bending CNT actuator into a PCB design, which enables a frictionless induction of movement onto a liquid. The driving electronics control the actuator with a low voltage and can be placed on the same PCB. The result is a smooth, tailorable dispensation of liquid from the pipette with the ability to integrate the pipette into a fully automated system