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Smart fabric: Cloth with electronic components

Photo: iStockphoto / Getty Images

Digitalization doesn’t even stop at our clothing. Scientists have been working on smart clothes for a long time, for example on sweaters with screens or pants with surveillance technology. A team of researchers from Singapore and China has now taken a step further. It has developed a process for producing threads for clothing with electronic functions, so-called wearables.

Until now, there has been one hurdle when implementing electronics in tissue: the semiconductors such as silicon and germanium, which are important for such applications, tend to crack during the production process. The group led by Lei Wei from the Nanyang Technological University in Singapore analyzed the process and, according to their own statements, improved it so that the threads can be manufactured with a much higher throughput and very good quality. They describe their approach in the scientific journal “Nature”.

The team produced a hat from its fiber. Using an optoelectronic sensor, the headgear can register whether a pedestrian traffic light is red or green. The hat then informs a visually impaired user whether the street can be crossed or not via a vibration signal.

It would also be possible to process the fiber into a bracelet for a smartwatch that adapts to the surface of the skin and measures the pulse rate. Because the fiber produced can withstand the pressure that exists at a depth of 3,000 meters, it can also be used for underwater applications, they say.

The so-called Molten Core method is particularly promising for obtaining extremely thin silicon or germanium threads. A semiconductor core is covered by a thick layer of glass. Both are heated together until they are viscous and stretched. But the thread often breaks while it is cooling.

Complex procedure

Wei and colleagues found that tensions arise in the glass-coated thread both when the semiconductor solidifies and when it cools down. These stresses are due to different melting points and thermal expansion rates of the materials.

The researchers achieved significantly better results when they combined germanium with aluminosilicate glass and silicon with very hard quartz glass. After cooling, the glass is removed in an acid bath and the semiconductor thread is combined with metallic conductors and plastic to form an optoelectronic fiber.

Xiaoting Jia and her colleague Alex Parrott from the Virginia Polytechnic Institute and State University in Blacksburg, USA, the results appear promising. In a comment on the study in "Nature" they write: "Another significant advantage of this technology is its industrial readiness." The fiber drawing device used is already used in the production of commercial optical fibers in the telecommunications industry.

Once the fibers are created, they can be knitted or woven into fabrics using tools widely used in the textile industry. The study takes "a big step toward integrating microcomputers into everyday clothing," said Jia and Parrott, who were not involved in the work.

dpa/joe