Textile sensor measures heart rate

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There is growing interest in smart textiles for medical applications. Extreme flexible fiber optics woven into fabric now let clothing measure the pulse.

Thanks to a melting technique, a team from Empa in St. Gallen produced what are known as polymer optic fibers in a particularly flexible form. They used the fibers in a sensor woven into material, which enabled them to measure the heart rate of test subjects.

Normally, these fibers, which are usually associated with communication technology, aren’t flexible enough. If they bend too much, they become damaged. The researchers’ goal was to create sensors that are fully integrated in textiles – in other words, a fiber that can also be sewn and does not break if knotted.

Textile sensor in the form of a hat

The textile sensor can also be produced industrially and is able to withstand a disinfection wash cycle. This makes it just the ticket for the hospital sector to monitor the skin’s circulation and prevent bedsores.

The researchers tested their textile sensor in the form of a hat, which enabled them to measure the test subjects’ heart rates on their foreheads. Normally, you measure the pulse on thin parts of the body, such as a finger or earlobe. By sending light through the tissue and measuring the light intensity that changes with the pulse as it returns to the detector, the heart rate can be determined.

One of the advantages of the new sensor is that it can be used on any part of the body as it measures the reflection of light – i.e. the sensor emits and measures light on the same side of the body. The sensor merely needs to lie on bare skin.

The researchers are now looking to refine their textile sensor so it can measure other data. It would be possible to monitor oxygen saturation or metabolic products with it, too.

Apart from the hospital sector, the sensor might also be interesting for sports clothing, for example – wherever measurements are required without causing any unpleasant rubbing on the skin.

Textile sensor (Image: EMPA)

Optic fibers for sensors are ideal for textiles. (Image: EMPA).