Smart threads store data

C&I Issue 9, 2017

US scientists have stored bytes of data in a smart fabric, by using conductive threads. Woven into a shirt or lab coat, for example, the threads could store invisible passcodes to open the door of your workplace or unlock a home safe. 

‘We can embroider these conductive threads into regular textiles, and then polarise each cell [patch of fabric] with a north or south pole to embed a 0 or 1,’ explains lead author Justin Chan at the University of Washington in Seattle. 

The researchers took a thin strip of conductive fabric, divided it into patches or ‘cells’ 2cm in length. They then used an ordinary magnet to magnetise each cell with a north or south pole, equivalent to 0 or 1; these ‘bits’ of data – zeros and ones - could subsequently be read by a smartphone.

‘All smartphones can sense whether conductive thread is nearby,’ Chan explains, because they contain a component called a magnetometer embedded in smartphones to provide a digital compass.

The fabric can be thought of as a hard disk, storing data on our clothes. In one example, researchers stored a passcode to an electronic door lock on a patch of conductive fabric sewn into a shirt cuff, and then unlocked the door by waving the cuff in front of an array of magnetometers. 

The fabric patch retained its data after machine washing, drying and ironing. Like hotel keys, however, the strength of the magnetic signal drains away with time, losing around one-third of its strength after a week, according to researchers presenting their work at a conference in October in Québec City, Canada (Proceedings of the 30th Annual ACM Symposium on User Interface Software and Technology, 2017, DOI:10.1145/3126594.3126620).

Possible applications include as an unobtrusive alternative to barcodes or RFID tags for use in clothing stores, and in uniforms for medical staff or hotel employees, to gain access to authorised areas.  The computer scientists are now improving their fabric to store information reliably over longer periods, Chan says.

Steve Beeby at the University of Southampton, UK, says the technology is ‘a good idea,’ but points out that ‘at present it stores a limited amount of data. This could be improved by reducing the size of the magnetic poling rig and data reading system. This would make reading it with a normal phone difficult and require bespoke reading equipment, but it should be entirely possible.’

Beeby is leading an EPSCR-funded project that knits together his interests in energy harvesting and wearable smart textiles. He predicts that smart fabrics, or e-textiles, will become widespread in medical, military and fashion domains.  However, ‘the technology has to be made reliable, practical and cheap,’ he says: ‘There are lots of research challenges remaining.’

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