Glass microfibres in textiles use acoustic waves to measure touch, pressure and movement

Researchers at ETH Zurich have developed smart textiles that use acoustic waves instead of electronics to measure touch, pressure and movement.

SonoTextiles work with glass microfibres that conduct sound waves; data processing is efficient thanks to use of different frequencies.

The researchers have woven glass fibres into the fabric at regular intervals. At one end of each glass fibre is a small transmitter that emits sound waves. The other end of each of the glass fibres is connected to a receiver that measures whether the waves have changed.

Each transmitter works at a different frequency. This means it requires little computing power to determine which fibre the sound waves have changed on.

This graphic shows how the glass fibres are woven through the fabric and function as a T-shirt. — The glass fibres are woven through the fabric at regular intervals (left). A transmitter (T) passes acoustic waves through the glass fibres, while the receiver (R) measures the waves at the other end. Im

When a glass fibre moves, the length of the acoustic waves passing through it changes, as they lose energy. In the case of a T-shirt, this can be caused by body movement or even breathing. “We used frequencies in the ultrasonic range, around 100 kilohertz – well beyond the range of human hearing, which is between 20 hertz and 20 kilohertz,” says ETH’s Yingqiang Wang emphasises.

This illustration shows what happens when the glass fibres are touched and the energy loss of the signal strength. — The wavelength in the glass fibres changes as soon as they are touched or bent.

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David Manners

David Manners has more than forty-years experience writing about the electronics industry, its major trends and leading players. As well as writing business, components and research news, he is the author of the site's most popular blog, Mannerisms. This features series of posts such as Fables, Markets, Shenanigans, and Memory Lanes, across a wide range of topics.