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Maybe you’re still warming up to wearables, but would you pull on a sweater that’s a circuit board? You soon could, because a team of engineers from Hong Kong Polytechnic University have created a fabric knitted with wiring that can be worn and even washed. This fabric could someday host a variety of devices for biometric monitoring, and the researchers write that it could be especially useful for law enforcement or military personnel.
This isn’t the first computerized fabric— ball boys at this year’s US Open are sporting bio-monitoring T-shirts —but it might be the most durable, as a paper in the September 3 Proceedings of the Royal Society showed it can withstand being stretched, folded, washed, wrinkled, and even shot with bullets.
Fabric circuit boards need to be able to fit all the criteria of printed circuits, as well as be durable, breathable, and safe to wear. They should also be washable, because a stinky shirt computer would be a huge setback for wearables. The researchers first tested for durability by repeatedly running it through a gauntlet of stretching, shearing, and folding. The fabric made it through a million of these cycles before its electrical capabilities began to wear down. They then washed and dried 30 samples 30 times in warm water in a conventional washing machine. Only 6 of the 30 samples had noticeable drops in performance. In subsequent wash/dry tests, the researchers lowered failure rate by experimenting with a more delicate spin cycle and putting the fabric in a protective mesh bag.
To make sure it could meet the most extreme job requirements of their target audience, they sewed pieces of the fabric and sensors into bullet proof vests, then shot bullets at it. Under the Kevlar, the fabric was protected from being blown to pieces, but still had to withstand withstood the incredible strain of impact. All the sensors were able to receive and transmit electrical signals after being shot.