Why the interest in e-textiles?
The heart of the e-textile business as it emerges is electric and electronic functionality from sensing to light emission, achieved entirely by use of e-fibers. Components and interconnections intrinsic to the fabric, or at least widely distributed through the fabric, are less visible and not susceptible to becoming tangled together or snagged by the surroundings. An e-textile can be worn in everyday situations where currently available wearable electronics would hinder the user.
The giants of many industries are just starting to take an interest in e-textiles. E-textiles involve the apparel industry, smart inks from the chemical industry, conductive fibers and for the future, disruptive technology such as yarn that senses, converts ambient energy into electricity (energy harvesting) and stores it over the whole garment, bandage etc. This concerns distributed functions in the main, with integration, invisibility, washability (or disposability), medical requirements and the artistry of the fashion industry variously being paramount. There is radio frequency identification (RFID) electronics behind some designer labels in fashionwear for brand protection purposes such as anti-counterfeiting and tracking grey markets and for stock control but it does not yet involve e-fibers. Other examples include the very visible laminates on apparel that emit light in changing coloured images.
E-textiles may involve skin patches, drapes, apparel and many other things and these requirements are different. E-textiles can also more easily adapt to changes in the computational and sensing requirements of an application, a useful feature for power management and context awareness. Indeed, it is likely that e-textiles will be the end game with many discrete items of consumer, military, industrial and medical electronics today. You are less likely to lose a device if it forms part of your apparel and it may be lower cost if made that way, eventually, and certainly more robust.
E-textiles are also known as electronic textiles or a form of smart textiles. Many intelligent clothing, smart clothing, wearable technology and wearable computing projects involve the use of e-textiles but they will open up huge new markets. Imagine the big designer fashion brands using the functionality in apparel and accessories at high prices.
A new IDTechEx report, E-Textiles: Electronic Textiles 2014-2024 gives the detail. In line with common practice, IDTechEx refers to both electronics and electrics as electronics in this report because nowadays they increasingly merge into one device or fabric. Electronics is evolving, the new forms sometimes creating additional markets and sometimes replacing earlier forms.
There is a surge of investment in wearable electronics, including investment funds, crowd funding, Google, Apple, Intel, Nike and Adidas. Initially, almost all of that concerns discrete devices such as smart watches and glasses but some attention is beginning to turn to electronic and electrical apparel and textiles, of which e-textiles form a part. There is likely to be a surge of investment in the e-fibers that give e-textiles their electronic functionality during the coming decade.
Part of the reason for the poor progress that we forecast in true e-textile sales, as opposed to sale of e-textiles embedded with conventional devices, lies in the difficulty of the technology - where almost everything has to be re-invented, and partly because the development programs poorly align with what is needed, only energy harvesting (locally producing electricity from ambient energy) being addressed in a properly balanced way with photovoltaics a priority and multiple energy harvesting strongly addressed by adding piezoelectrics and other options. In electronics there is very little development of any weavable fiber component beyond some sensors. In electrics there is some work on battery e-fiber and quite a lot on supercapacitor e-fiber and on photovoltaic harvesting with energy storage together. However, not much is being done on rechargeable battery e-fiber. All together then, the portfolio of component functions being prepared is insufficiently broad for much to be designed by way of complete circuits even ten years from now. Anyway, textile manufacturers are hesitant to work with completely new fibers.
Where are the electronic circuits?
"We don't want humans to be aware of what they are wearing," said Maksim Skorobogatiy, a physicist at Ecole Polytechnique de Montreal in Canada in 2014. "It has to be self-contained piece that can charge itself, store energy and perform useful functions. Otherwise, it's an extra burden that nobody needs in our lives.... We're moving toward a self-contained textile battery, electronics and sensors, all made with textile thread. At this point, we're only missing the electronics." It means that most commercial successes in electronic and electric textiles over the coming decade will be at best only partly involving woven e-fibers ie true e-textiles, with laminates and other distributed structures containing conventional components being the only option for much of what will be desired.
Transistors are used in most forms of electronics so you would think they would be the first to be developed in a new form such as printed flexible electronics and e-fibers. However, they are very challenging because the inks can be very expensive, the yields poor and the performance results primitive. The result is that the last five years has seen no major success in commercialising transistors in either the printed flexible or the woven fiber form. Earlier work on woven fiber transistors led to nothing. Fibers are a poor geometry for many electronic circuits such as transistors, where large numbers are usually required, the 14 transistor ring oscillator for winking labels etc. or the timer being fairly simple but with little incentive to put them on one or a few fibers and the basic RFID tag with 1000 transistors being too low cost for anyone seriously to attempt the necessary 2 cent version on fibers - a massively daunting task. Trapping tiny microchips, LEDs etc among the fibers is so much easier, more affordable and far more functional.
For more information see E-Textiles: Electronic Textiles 2014-2024
Top image = (No)where (Now)here: two gaze-activated dresses by Ying Gao