If you don't like the idea of your boss implanting a chip in your hand to let you open doors and log into office computers, a team from the University of Washington has developed a system that doesn't require quite so big a commitment. It allows passcodes to be stored in your clothes without electronics, courtesy of a patch of magnetic fabric that can be read by sensors at a door or vending machine.

Conductive thread has been used to make health-monitoring wristbands and Solar Bikinis, but the UW team realized the material wasn't just useful for conducting electrical signals: it could be magnetized to store digital data like a hard disk. Codes can be written to the conductive fabric by rubbing magnets on them to generate ones or zeroes in certain sections, which can then be read by simple magnetometers to verify a specific signal and grant access to a computer or approve a payment.

Perhaps the most important feature is that all the electronics are in the readers only, so there's no need to embed them in the clothes themselves. That means the material can be thrown in the wash without worry, which is more than can be said for other smart wearables that are weighed down with bulky electronics.

Of course, it wouldn't be much use if the codes came out in the wash, but in tests the researchers found that the fabric retained the data after a complete machine wash, dry and iron cycle, withstanding temperatures of up to 320° F (160° C).

"This is a completely electronic-free design, which means you can iron the smart fabric or put it in the washer and dryer," says Shyam Gollakota, senior author of the study. "You can think of the fabric as a hard disk – you're actually doing this data storage on the clothes you're wearing."

As well as embedding the magnetic fabric into the sleeve of a shirt, the team created a tie, belt, necklace and wristband that could all store data.

The system isn't without its potential pitfalls though. As anyone who's ever accidentally wiped a hotel key card by putting it in their wallet with a credit card knows, that magnetic signal can be flaky, and will degrade over time. The upside to that is that the fabric can be remagnetized multiple times.

As a bonus, the researchers also showed that the fabric can be used to interact with a smartphone via gesture recognition. They embedded patches of the magnetic fabric into the fingertips of gloves and demonstrated that the phone's built-in magnetometer could recognize six different gestures: up, down, left and right swipes, as well as a click and back-click. The phone picked up the correct signal 90 percent of the time, and even worked from inside a pocket.

"With this system, we can easily interact with smart devices without having to constantly take it out of our pockets," says Justin Chan, lead author of the study.

Next, the researchers plan to develop their own textiles that can generate a stronger magnetic field, which would allow them to store data at a higher density.

The research was presented at the User Interface Software and Technology Symposium last week, and the paper was published online (PDF).

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