The United States Develops Fibers That Produce And Detect Sound Waves.

For hundreds of years, Man-made fiber Refers to the raw materials of clothes and ropes. In the information age, the meaning of fiber has become the glass filament carrying data in the communication network. But for Joel Fink, an associate professor of Electronics Research Laboratory at Massachusetts Institute of Technology, the fibers used in textiles or fibers are too passive. Over the past ten years, his laboratory has been working on developing more advanced fibers to enable fiber fabrics to interact with their surroundings.

In a recent issue of the journal Nature and materials, Fink and his collaborators announced a landmark new model. Functional fiber A fiber that detects and produces sound. The application of this fiber includes: it can be made into clothes for microphone, can capture speech or monitor body function, or make a fine single filament that can measure blood flow or pressure in capillaries.

New fiber contains asymmetric Molecular plastic

Ordinary optical fibers are made from "prefabricated" products, and the prefabricated products are a large cylindrical single material that can be heated, drawn and cooled. In contrast, the fiber developed by Fink laboratory is a careful geometric arrangement of several different materials, enabling them to remain intact in heating and stretching processes.

The core of the new acoustic fiber is a plastic commonly used in microphones. The fluorine content in this plastic enables researchers to ensure that their molecules are in an unbalanced state, that is, fluorine and hydrogen atoms are on one side, even during heating and stretching. The asymmetry of this molecule causes plastic to have "piezoelectricity", which means that when an electric field is applied to it, it will change its shape.

In traditional piezoelectric microphones, the electric field is produced by metal electrodes. However, in a fiber microphone, the stretching process causes metal electrodes to lose their shape. Therefore, researchers substituted graphite conductive plastics. Conductive plastics will produce a dense liquid when heated, thus maintaining higher viscosity than metal electrodes. This not only prevents the material from mixing, but also more importantly, it also gives the fibers a normal thickness.

After the fibers are stretched, the researchers need to arrange all the piezoelectric molecules in the same direction. At this point, a strong electric field (20 times stronger than the lightning induced lightning field) is needed. Because everywhere in the fiber is very narrow, it produces a tiny lightning ball that destroys the surrounding matter.

Vocal fiber is widely used.

Although this delicate balance is needed in the manufacturing process, researchers are able to produce this functional fiber in the laboratory. If they are connected to a power source and applied to a sinusoidal current (very stable alternating current), these fibers will vibrate. If it vibrates at the audio frequency and near its ears, it can hear different notes or sounds. In the papers on nature and materials, researchers have measured the acoustic properties of fibers more strictly. Because water can spanmit sound better than air, they put fibers in a tank opposite to the standard sound energy converter. The sound spanducer can send out the sound waves detected by the fibers alternately, and can also detect the sound waves emitted from the fibers.

The researchers hope to eventually synthesize the properties of these experimental fibers into a single fiber. For example, strong vibration can change the optical properties of reflective fibers, so that fiber fabrics can be used for optical communication. In addition to wearable microphones and biosensors, the application of the fiber includes a network capable of monitoring the flow of water in the ocean and a high-resolution large area sonar imaging system. The fabric made of this acoustic fiber is equivalent to millions of tiny acoustic sensors. The researchers say that using the same mechanism, a piezoelectric element can turn power into motion in turn.