To Charge your iPod, Plug in Your Jeans

A breakthrough in wearable computing lets researchers�change ordinary cotton and polyester into electronic textiles that can double as rechargeable batteries. That means powering an iPod or cell phone could become as easy as plugging it into your tee shirt or jeans and charging the clothing overnight.

“Energy textiles will change the development of wearable electronics,” Liangbing Hu, one of the researchers from Stanford University involved in the project told Wired.com. “There are not that many solutions available for energy storage for wearable devices. Electronic textiles tries to solve that problem.”

Wearable electronics is an attempt to create a new category of devices that are flexible and lightweight such as wearable displays, embedded health monitors and textiles with electronics melded in.� In case of textiles, though, most attempts, so far, to integrate electronics involve patching sensors and resistors on to existing fabric.

The latest attempt tries to bring the electronics to the molecular level. The researchers coated cellulose and polyester fibers with ‘ink’ made from single-walled carbon nanotubes. The nanotubes are electrically conductive carbon fibers barely 1/50,000 the width of a human hair.

The process of dyeing with this special ink is similar to that used for dyeing fibers and fabrics in the textile industry, they say. Details of the method were published in a paper in the ACS’ Nano Letters journal.

The coating makes the fibers highly conductive by turning them into porous conductors. The treated textiles can then be used as electrodes and standard textiles used as separators to creates fully stretchable supercapacitors. Ordinary capacitors are used to store energy. Supercapacitors can offer turbocharge that principle such that the capacitor can be charged and discharged virtually an unlimited number of times.

“If you have a high surface area, you can store a high amount of charges,” says Hu. “Since we coat carbon nanotubes on textile fibers, it increases the surface and allows for charge and discharge cycles up to one million times,” says Hu.

The electronic textiles produced by this method retain the flexibility and stretchability of regular cotton and polyester. They also kept their electronic properties despite simulated repeated laundering, say the researchers.

The next step is to combine it with inks of other materials that could help turn the fabric into wearable solar cells and batteries.

The researchers are also looking to use graphene, a form of carbon derived from graphite oxide, instead of carbon nanotubes. “Graphene can be much cheaper than nanotubes,” says Hu, “so alternative materials like that could significantly reduce the cost of energy textiles.”

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