A long-standing dream of a certain cadre of computer specialists is to create smart textiles that can sense their environment, store, transmit and process information as well as harvest and store the energy necessary to do all this. A particular driver of this technology is the military which would very much like to remotely monitor the health and status of troops on the battlefield.
But creating truly smart textiles is easier said than done. One problem is that clothing generally has to be soft and flexible, something that chips, wires and sensors usually are not. A second problem is that most clothing is made from woven materials which must be made from soft flexible strands.
That’s not to say that some progress has not been made. For example, certain conducting polymers can be drawn into fibres and woven into a material to form a kind of wearable motherboard. It is then possible to fasten electronic components such as chips, sensors and batteries to this motherboard.
But that’s a fiddly, time-consuming process. One thing that could help is more useful fibres. And today Jian Feng Gu from Ecole Polytechnique de Montreal in Canada and couple of buddies reveal one that could help.
Their idea is to create a simple rolled capacitor from a sheet of conducting polymer sandwiched between two insulating sheets of low density polyethylene. They then roll this sandwich into a cylinder and encase it in high density polyethylene.
There’s nothing unusual about this kind of rolled capacitor. But what Gu and co do next is. They heat it and then extrude it through a tiny hole to form a fibre with a diameter of less than a millimetre.
If the conditions are just right, the plastics all stretch in exactly the same way so that the internal structure of the fibre is just a smaller version of the original.
And that’s exactly what happens. Gu and co say their fibre is soft and flexible and has a capacitance some 1000 times greater than an equivalent co-axial cable.
That could turn out to be handy. Gu and co say that the capacitor should be able to store energy harvested by other devices such as piezo-electric fibres that might also be woven into a textile. And by combining the capacitor with an inductor, it ought to possible to build all kinds of capacitor-inductor sensing circuits too.
Which means that this fibre or something like it could turn out to be an important component of smart textiles in future.
Ref: arxiv.org/abs/1006.5221: Soft Capacitor Fibers Using Conductive Polymers For Electronic Textiles