A collaboration between researchers at the University of Surrey's Advanced Technology Institute and the Faculty of Mechatronics of Warsaw University of Technology in Poland reports that low electrical loss at frequencies of up to 220 GHz are possible in screen printed carbon nanotube - polymer composites.  Producing such low electrical loss materials potentially opens up new types of high frequency large area electronic devices.

A carbon nanotube (CNT) is a rolled up sheet of graphene that has a diameter of only a few nanometers.  This size is equivalent to thousandths of the diameter of a human hair but despite their small size CNTs have outstanding properties such as high strength and an ability to carry a very high electrical current.  Building upon previous EPSRC-funded research in carbon nanotube polymer composite electronics, this study, published recently in the American Institute of Physics journal Applied Physics Letters, shows that CNT composites have electrical losses of less than 0.3 dB/mm over a wide frequency range.  Embedding CNTs in a polymer, in this case PMMA, allows accurate control of the nanotube content and control over the conductive phase of the composite which was screen printed into coplanar waveguides to produce structures tens of mm in length.  Using a screen printing technology allows for ease of scalability for production and relaxes many of the constraints found in high end manufacturing techniques.  Possible applications include new types of microwave mixers, phase shifters and antennas.

Dr David Carey from the Advanced Technology Institute of the University of Surrey said: "The success of the research is to be found by employing the unique high frequency electrical characterisation facilities at Surrey to explore electrical conduction in large area carbon nanotube based composites.  Understanding what controls the conduction at the nanometer scale in these new materials can lead to the development of new high frequency carbon nanotube based electronics."

Professor Ravi Silva, Director of the Advanced Technology Institute at Surrey, said "This research shows the transformational benefits that can happen of bringing high quality specialised experimental facilities to tackle some of the key problems in modern nanotechnology and electronics.  The research offers the potential for new applications of carbon nanotubes."

For further information please see "Electrical performance of carbon nanotube-polymer composites at frequencies up to 220 GHz" by Ali H. Alshehri, Malgorzata Jakubowska, Marcin Sloma, Michal Horaczek, Diana Rudka, Charles Free and J. David Carey, Appl. Phys. Lett., Volume 99, 153109 (2011).  Further details can be found at http://dx.doi.org/10.1063/1.3651278