February 21, 2024
4 Min read
Sophisticated wires behind a hat that detects traffic lights
A new technique for making electronic fibers could help solve the problem of flexibility of portable technology
Hundreds of meters long, flexible to high performance fibers collected on a cylindrical coil, as well as preforms after the manufacturing process.
A team of electrician engineers and fabric scientists invented a hat that indicates to its carrier when it is sure to cross the road. The proof of proof of concept of researchers is knitted with Germanium fibers which can detect traffic changes – and say to pedestrians with visual deficiencies when they are clear to walk. This prototype shows how fibers with a semiconductor core can be woven in functional clothes that gather, process and store information, and this can one day lead to computers that can be worn as clothes.
The manufacture of conductive fibers which are flexible enough to use in clothing is not easy. The crystalline forms of the elements of silicon and germanium – taken by the portable electronic industry for their optical and electric properties – must be locked in a protective coating, then turn into lasting strands. Previous attempts that used a process called thermal drawing could only produce strands that were generally too short (generally more than tens of centimeters) and fractures left or other disabling defects in nuclei. But now, for the first time, researchers have developed a method that creates long and flexible fibers with intact light detection properties and electronic properties – as does the woven hat. The team described these results in a recent study in Nature.
In a typical thermal drawing process, silicon is placed inside a glass tube and heated until the two materials are soft enough to stretch in thin fibers. But “because silicon and exterior glass jacket are completely different, when we warm them up, they will display completely different behaviors” in their ability to stretch, says the main author of the new Lei Wei study, which does research on functional tissues at the Nanyang technological university in Singapore. The difference in the way in which these materials develop or shrink can emphasize the fibers and break their semiconductor nucleus. “Stress is the killer,” said Wei.
On the support of scientific journalism
If you appreciate this article, plan to support our award -winning journalism by subscription. By buying a subscription, you help to ensure the future of striking stories about discoveries and ideas that shape our world today.
To solve this problem, Wei and his team brought engineers in mechanics to help identify the forces at stake at each stage of the heating and stretching process. “We used their theory to guide our selection of materials,” says Wei. Once the study authors found the right combinations, they were able to make fibers that survived the manufacturing process without defects or breaks, as they reported Nature.
By placing silicon inside the silica glass and Germanium in the aluminosilica glass, the researchers produced continuous fibers which measured about 100 meters long. Then, they engraved the glass covering and heated and stretched the fibers again, this time by integrating the semiconductor nuclei inside a polycarbonate plastic. “The fibers are super flexible,” explains Wei, so that they can be knitted or woven with fabrics such as cotton, wool or silk in “functional textiles”. The researchers produced a prototype fabric which was about a meter wide and 10 meters long. The fibers worked underwater and also survived other sustainability and compression tests.
Xiaoting Jia, who leads a research group on intelligent fibers and portable devices at Virginia Tech, says that this work will open the way for a larger scale of semiconductive fibers based on silicon or Germanium. The inclusion of the polymer layer, she says, adds flexibility and insulation and protects fiber when woven or knitted in fabric. “It becomes a very robust and scalable process,” adds Jia, who was not involved in the study but co-wrote a comment to support in research in research Nature.
Potential applications include optical technology, such as the light detection hat. The hat fibers feed the data with a small interface card inside the hat. This card communicates with an application that means that the carrier’s smartphone vibrates differently to indicate when a traffic light has become red or green.
Another prototype created by the team is a sweater that incorporates optoelectronic silicon fibers. The garment receives and sends data using the Light-Fidelity communication (LI-FI). In the study, the information, in this case, a photograph of a building, has been converted into a binary code and transmitted by the sweater in the form of light pulses. Researchers have also demonstrated a flexible surveillance strip that monitors heart rate.
Thanh Nho Do, a gentle robotics and functional materials expert, who heads the New South Wales Medical Robotics Laboratory in Australia and has not been involved in the study, says that the new technique produces semiconductor fibers which are strong enough to be woven by hand or by machine-and are suitable for large-scale manufacturing. “It can open new possibilities to integrate more functions,” he says, such as sensors that detect pressure or temperature or soft robots controls.
The new results can guide researchers in the selection of materials and the design of structures for more complicated semiconductor nucleus fibers in other elements, explains Wei. His team has kept its simple structures for the moment, but future textiles could double as more complex appearances. An current project is to try to transform fibers into transistors: a necessary step towards the possibility of weaving a computer device. Although the first prototypes are limited to sensors, Wei is optimistic that a laptop could come in the future.
