Graphene: State of the market and trend

Graphene material with extraordinary properties, attracted the attention of scientists already inthe 1960s but it was not up till 2004 that it was proven to exist in a free form. Since that time the increasing interest has been observed based on the continuously increasing number of publications and patents. In 2012 the first product reached the market. It is predicted that the extensive reseraach will bring further products and expansion of graphene market in the coming 10 years, with the greatest grow in the user of graphene in energy storage devices such as capacitors

Graphene prodcuts and production

Graphene, a one-atom-thick flat sheet of carbon, has received plenty of attention especially after groundbreaking experiments on its properties were rewarded with the 2010 Nobel Prize in Physics. This single layer of graphene is simultaneously the world's thinnest, strongest and stiffest material, as well as being an excellent conductor of both heat and electricity. The vast amount of interest in graphene and its properties is reflected by approximately 3,000 research papers and more than 400 patent applications [1]. Also the amounts of funding that the graphene research is obtaining from both governments and industry is impressive. However, up till now no products utilizing graphene are available on the market. This presentation analyses the future perspectives of the market and product development and to this extend the need for the mass production of this material. As specific production methods, Chemical vapour deposition (CVD) and electrochemical exfoliation are introduced. Supporting the trend among the material manufacturers, who concentrate their efforts on not only development of the material, its production methods but simultaneously the applications, the EU funded project ElectroGraph (GA no. 266391) is presented

Carbon nanotube composites

Carbon Nanotubes (CNT) due to their extraordinary mechanical, electrical and thermal properties are being extensively investigated as the filler material for composites. This talk focuses on the development carried out at Fraunhofer IPA and presents IPA as the specialist in the development of processes for dispersing CNTs in a wide range of matrices and production techniques for the corresponding compounds. Among them one can find CNT dispersions in liquid solutions, including water, as well as in high viscosity mediums. Composites, in which CNTs are utilised as a filler material, are based on polymers, metals and ceramics. Products containing CNTs that were developed at Fraunhofer IPA (formerly Fraunhofer TEG) and further potential applications of those materials are presented

Carbon nanotube actuators

Carbon Nanotubes (CNT), die aufgrund ihrer elektro-mechanischen Eigenschaften und der Auslenkungsreaktion unter Anlegung von elektrischer Spannung, gehören zu der Gruppe der elektroaktiven Aktormaterialien. In dieser Präsentation die Entwicklung des Fraunhofer IPA im Bereich Aktuatoren werden vorgestellt. Unter am Fraunhofer IPA untersuchten CNT Aktoren kann man unter anderem Bucky Papers finden, die in flüssigen Elektrolyten betrieben werden, sowie CNT-Polymer-Verbundwerkstoffe, die als "trocken" Aktoren dienen. Die Aktuationsverhalten ist als out-of-plane und Biegeauslenkung untersucht. Innerhalb dieser Vortrag werden die Prinzipien der Aktuationsmechanismus vorgestellt, gefolgt von der Leistungsergebnissen in Bezug auf die Auslenkung, erzeugte Kraft, Reaktionszeit und Reproduzierbarkeit. Die neuesten Entwicklungen der Aktoren im Bereich der Kontaktierungsmethoden, Stapeln von Aktoren und deren Integration in Systeme, werden ebenfalls vorgestellt

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

Nanocarbons as electrode materials for supercapacitors: Poster at Batterietagung 2013, Batterietag NRW, 25. Februar 2013, Aachen; Kraftwerk Batterie, 26.-27. Februar 2013, Aachen

Electrochemical double layer capacitors (supercapacitors) are expected to play a significant role in future hybrid power systems due to their high specific power, cycle life, and tolerance of extreme environmental conditions. The development of flexible, conformable energy storage devices is also of great interest due to ease of packaging and coupling with flexible electronics. Because supercapacitors store charge only on the electrode surfaces, maximizing the amount of surface area that is accessible to the electrolyte ions is of critical importance. Carbon is an excellent electrode material due to a variety of favourable chemical properties, including chemical stability and large electrochemical windows and thus currently the most common electrode material is activated carbon. Currently however, the nanocarbons, as a new class of materials, offer properties and potential to be implemented in electrodes of energy storage devices resulting in an overall improvement of system performance. Among those novel materials one can consider carbon nanotubes, carbon nanohorns and graphene and its derivatives. In this talk the potential of nanomaterials will be presented and supported by the results of EU funded ElectroGraph project (Graphene-based electrodes for application in supercapacitors). This project follows an integrated technology driven approach where the research and development activities stretch out from the material synthesis, through properties engineering and processing of grapheme materials towards their applicability as electrode for energy storage. Together with the technological development, the experience based understanding of appropriate practices for the safe production, processing and recycling of graphene nanomaterials is being generated, and will facilitate the development of guidance on risk management and best available techniques to minimize and control any health risks to manufacturers, downstream users and the environment

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