Intelligent textiles: T-shirt measures breathing via sound waves
Researchers use sound waves that travel through glass fibers woven into T-shirts to measure the wearer's movements. This enables a wide range of applications.
(Image: Yingqiang Wang / ETH Zurich)
A research team at the Swiss Federal Institute of Technology in Zurich (ETH Zurich) has modified a common textile fabric by weaving in glass fibers so that it can be used as a T-shirt to detect changes in the wearer's movements via sound waves. The SonoTextiles can also react to pressure and touch. The scientists use this property to measure breathing, for example.
Most intelligent textiles require some electronics to be able to record biodata with sensors, for example. The system developed by the researchers at ETH Zurich, on the other hand, requires less. Accordingly, the textile is lightweight, breathable, easy to wash, inexpensive and requires very little energy, write the ETH scientists in the study “A smart acoustic textile for health monitoring”, published in Nature Electronics.
The sensor technology essentially consists of glass fibers that are woven into the textile at regular intervals. A transmitter of sound waves and a receiver are located at each end. The transmitters operate at different frequencies, which are monitored by the receiver and detect changes. This method makes it easier to determine on which fibers the sound waves have changed. It also requires very little computing power.
“We used frequencies in the ultrasonic range, around 100 kilohertz – far beyond the human hearing range, which is between 20 hertz and 20 kilohertz,” explains Yingqiang Wan, first author of the study.
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As soon as an optical fiber moves, the acoustic wavelength changes because it loses energy. If the system is woven into a T-shirt, for example, body movements such as the rising and falling of the chest can be recorded and breathing can be measured.
Wide range of possible applications
The intelligent T-shirt can be used to monitor the breathing of asthma patients, for example. If the breathing rate changes, this could indicate a problem and trigger an emergency alarm. It is also possible to monitor the movements of athletes, the researchers write. This could help prevent injuries, for example. SonoTextiles could also be used to improve posture by providing feedback on when a poor posture should be corrected. In addition, wheelchair users could also be informed when they should change their position to avoid pressure sores.
The scientists at ETH Zurich have also identified another field of application for their intelligent textile: SonoTextiles could also be used to produce gloves that detect hand gestures and movements. Users could use these to control computers or evaluate hand movements in augmented reality environments, for example.
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However, the researchers have not yet solved one problem with SonoTextiles. In practical use, the glass fibers could break in continuous daily use. The scientists therefore want to investigate whether metal can be used instead to make SonoTextiles more robust.
(olb)
