Internet of pants? This ultrathin thread could make your clothes part of the IoT

Your clothes could one day monitor your fitness levels or boost your smartphone reception thanks to a new technique that uses ultrathin electronic thread to embroider circuits into fabric.

Measuring just 0.1 mm in diameter, the thread comprises seven filaments made of copper and silver. Using it, researchers at Ohio State University have found a way to embroider circuits into fabric with enough precision to integrate electronic components such as sensors and memory devices into clothing. 

Ultimately, such "e-textiles" could be used to create shirts that act as antennas, bandages that tell your doctor how well a wound is healing, or even caps that sense activity in the brain.

“Now, for the first time, we’ve achieved the accuracy of printed metal circuit boards, so our new goal is to take advantage of the precision to incorporate receivers and other electronic components," said John Volakis, director of Ohio State's ElectroScience Laboratory.

The researchers used a standard tabletop sewing machine to embroider the e-textiles. The shape of the embroidery determines the operating frequency of the antenna or circuit.

One broadband antenna, for example, consists of more than half a dozen interlocking geometric shapes, each a little bigger than a fingernail, that form an intricate circle a few inches across. Each piece of the circle transmits energy at a different frequency, so together they cover a broad spectrum. That embroidery takes about 15 minutes to create and uses about 10 feet of the specialized thread, for a material cost of roughly 30 cents per antenna.

In tests, an embroidered spiral antenna measuring about six inches across transmitted signals at frequencies of 1 to 5 GHz with near-perfect efficiency, the researchers said, making it well-suited for broadband Internet and cellular communication.

A paper describing the researchers' results was published recently in the journal IEEE Antennas and Wireless Propagation Letters. Ohio State plans to license the technology for further development.