www.afm-journal.de FEATURE ARTICLE © 2014 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 3661 www.MaterialsViews.com wileyonlinelibrary.com electron transport, lack of skin effect, cur- rent carrying capacity exceeding super- conductors, mechanical strength/stiffness better than any metal, thermal conductivity exceeding diamond and many other prop- erties. This amazing list can be extended by advantages such as the wide availability of carbon sources, the potential low-cost of large-scale production and their zero net carbon footprint, together these attributes make carbon nanotubes an obvious candi- date for “the material of the future”. One very interesting potential applica- tion of carbon nanotubes is in electrical wiring. Conventional electrical wires made of copper and aluminium suffer from sev- eral problems including: weight (an issue in aerospace applications), skin effect (hindering their use in modern telecommunications), mechanical performance (critical in overhead power lines), and electromigration (severely dam- aging microscopic wires in electronics applications). Moreover, the growing demand for these conventional metal conductors and their continually increasing prices suggests that a low-cost material that can outperform conventional conductors would be highly desirable. Hence, carbon nanotubes are the material of great interest. However, there are several challenges in the production of carbon nanotube electrical wires and their application, which include; preparation of macroscopic structures that retain the properties of individual nanotubes, control over the mor- phology and dimensions of these structures, development of large-scale cost-effective manufacturing processes and pro- viding the wires with suitable electrical insulation and connec- tions for integration into electrical systems. Not less impor- tant, is the in-depth understanding of the physics behind the transport properties of these new carbon structures and possible preparation of new standards for the use of the CNT wires. Some of the solutions to these issues have been already suggested. Several research groups have already succeeded in the pro- duction of macroscopic CNT fibers (also referred to as yarns or threads) which are long assemblies of axially aligned nano- tubes, of diameters in the micrometer range. [2–4] The theoretical and experimental research on CNT fibers predict that proper control of the morphology of these macro- scopic assemblies of CNTs should produce the material of excellent electrical conductivity comparable to the conductivity of individual nanotubes. [5] Electrical Properties of Carbon Nanotube Based Fibers and Their Future Use in Electrical Wiring Agnieszka Lekawa-Raus, Jeff Patmore, Lukasz Kurzepa, John Bulmer, and Krzysztof Koziol* The production of continuous fibers made purely of carbon nanotubes has paved the way for new macro-scale applications which utilize the superior properties of individual carbon nanotubes. These wire-like macroscopic assemblies of carbon nanotubes were recognized to have a potential to be used in electrical wiring. Carbon nanotube wiring may be extremely light and mechanically stronger and more efficient in transferring high frequency signals than any conventional conducting material, being cost-effective simul- taneously. However, transfer of the unique properties of individual CNTs to the macro-scale proves to be quite challenging. This Feature Article gives an overview of the potential of using carbon nanotube fibers as next generation wiring, state of the art developments in this field, and goals to be achieved before carbon nanotubes may be transformed into competitive products. 1. Introduction The ever increasing use of technology in all areas of our daily life has had an immense effect on our demand for electrical energy, and this has resulted in the urgent need to find more efficient methods for its generation and distribution. This need has stimu- lated the quest for new materials and highly efficient devices, which have significantly better performance than those currently in use, as well being cost-effective, safe, and environmentally friendly. In this perspective, carbon is a very promising material. The recent synthesis of fullerenes, carbon nanotubes and separation of graphene has generated enormous interest in these carbon materials. [1] Carbon allotropes of this type offer not only a highly exciting and vast area for scientific exploration but also the potential for a wide spectrum of novel engineering applications due to their properties. Carbon nanotubes are particularly attractive, due to their tubular shape, low density, tuneable electrical properties, ballistic DOI: 10.1002/adfm.201303716 Dr. A. Lekawa-Raus, L. Kurzepa, J. Bulmer, Dr. K. Koziol Department of Materials Science and Metallurgy University of Cambridge CB3 0FS, UK E-mail: kk292@cam.ac.uk J. Patmore Pembroke College Cambridge CB2 1RF, UK This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes. Adv. Funct. Mater. 2014, 24, 3661–3682