The advancement of electronics in textiles field has reached a new level. Earlier electronics were embedded in the textiles,which provides a wide variety of applications such as monitor homes for noxious chemicals, help firefighters maneuver in smoky buildings, help stroke victims recover their function and much more. With increase in the applications e-textiles become much bulkier, with full of wires and sensors,thus not suitable for mass production. Hence scientists moved a step forward and were successful in making the fabric itself as electronic device.
Scientists at the Textiles Nanotechnology Laboratory at Cornell University in Ithaca, New York, and the University of Cagliari in Italy have found a way of making transistors from cotton fibres.They say that the applications for their research could include carpets that know how many people have walked on them, firefighting suits that detect airborne pollutants and clothing that can incorporate heart-rate and sweat monitoring sensors.
At first turning cotton conductive is impossible because cotton is a natural conductor.Scientists have made this possible by coating individual cotton strands with gold nano particles along with conductive polymer PEDOT. To turn a cotton wire into a semiconductor, it was dipped in another polymer, and then a further glycol coating to make it waterproof. “We can definitively have sections of a traditional cotton fabric becoming conductive, hence a great myriad of applications can be achieved,” Hinestroza of Cornell university said.
This process improved the conductivity of the cotton by a factor of about 1000, with the material still retaining its suppleness. “The technology developed by us and our collaborators allows cotton to remain flexible, light and comfortable while being electronically conductive,” Hinestroza said. “Previous technologies have achieved conductivity but the resulting fiber becomes rigid and heavy. Our new techniques make our yarns friendly to further processing such as weaving, sewing and knitting.”
Two types of transistors,FET and electrochemical transistors (which can switch at low voltages,thus suitable for wearable computers)can be developed using conductive cotton fabric. “Instead of conventional wires, we are using our conductive cotton to transmit the electricity — so our conductive yarns become part of the dress,” Hinestroza said. “Cotton used to be called the ‘fabric of our lives’ but based on these results, we can now call it ‘The fabric of our lights.’”However, it’s still no match for a silicon circuit, because the electrons don’t travel as fast.
The end result, according to the research paper, is cotton yarns that can be used to fashion the basic building blocks of a computer circuit, but still retain their flexibility. These tailor-made cotton circuits will weave the way to, quite literally, wearable computers. For the first time, instead of incorporating small chips or flexible printed circuits, you will be able to build a t-shirt that is also a computer. Just think how many interconnections there are in a standard cotton shirt — it’s on the scale of hundreds of thousands or millions — and each one could become a transistor. We’re obviously a little way away from that reality, but the idea of incorporating sensors — radiation detectors, toxic substance detectors, heart beat monitors — is just around the corner.
Hinestroza said: ‘If you think about how many fibers you have in your T-shirt, and how many interconnections you have between the weft and the warp of the fabric, you could get pretty decent computing power.’