Written by: Bahadur Goonesh Kumar, S Rosunee, M. Bradshaw
Dr Bahadur Goonesh Kumar, University of Mauritius; Dr S Rosunee, University of Mauritius; & Dr M. Bradshaw, De Montfort University, UK
With the rising ubiquity of a wide range of electronic devices (smart phones, tablets, laptops) and the electromagnetic (EM) waves associated with them, it is becoming increasingly important that cost effective and versatile EM shielding technologies be developed. The two major problems associated with EM waves are that they destructively interfere with radio and wireless communications and they can potentially have an adverse effect on human health. Interference owing to EM waves can have serious consequences, both material and financial, for key national electronic installations, affect communication with the outside world and result in loss of economic opportunities.
Metal sheets are considered to be the best material for electromagnetic shielding as these are highly conductive and reflect the EM waves. However, metals are expensive, heavy, sensitive to temperature changes and are not flexible. Textile materials are well known for their fineness, flexibility (ability to conform easily to three-dimensional shapes) and relatively cheap. By integrating electrical conductive yarn into the structure of the fabric, the latter becomes electrical conductive and therefore can be used as EM shielding material. In this study, different knitted structures were produced using 100 per cent cotton and electrical conductive yarns and their ability to shield against EM waves in the frequency range of 400 to 1100 MHz were investigated.
In this work, electrical conductive yarns were plated with conventional textile yarns through knitting and the knitted structures generated have been investigated for their EM shielding efficiency. The 'hybrid' knitted structures made of 100 per cent cotton yarn and electrically conductive yarn produced different surface textures and therefore, different knitting structures were used, namely 1x1 plain ribs with plaiting, 1x1 plain ribs with horizontal stripes and Fair-Isle. Single and double-bed hand knitting machines, gauge 5 and 7 dpi, were used to knit the set of fabric samples mentioned above.
1x1 plain ribs with plaiting and 1x1 plain ribs with horizontal stripes
Fair-Isle samples knitted on a single bed machines