Diodes Can Now Be Embedded In Fibers

We all can imagine the level of integration of the electronic circuitry which can be reached in today’s era from the name of the topic itself, can’t we? Nothing seems to be impossible today due to the technological advancements and the increasing number of researches. The material scientists from MIT claim that they can build a simple semiconductor based device inside a fiber. The new and upcoming advanced manufacturing processes are capable of manufacturing fiber with logic and image processing. It also has some photovoltaic capabilities. The above mentioned attributes to a fiber will some or the other day lead to smart and self powered fabrics.

Nicholas Orf is a post-doctoral researcher in Yoel Fink's laboratory at MIT. With a huge knowledge base, he tried to synthesize a semiconductor material inside a fiber and he was successful in doing this. As this fiber embedded with semiconductor material is drawn, semiconductor materials form simple diodes with electrical contacts. He says that we can have a fiber as long as a kilometer. The progress report of their work is published in the early edition of "Proceedings of the National Academy and sciences".

He used polymer for this experiment and heated it until it was soft enough to flow. After this stage the fibers are drawn from it which are hundreds of meters in length but they have the diameter of the order of micrometers. So when you read this, you can imagine a semiconductor embedded in a fiber which has a diameter approximately as that of your hair. But this process had a problem. Many semiconductors have a high melting point and they do not flow at the temperatures at which drawing process is carried out. This problem was done away by the Multistep process. They used Zinc selenide compound semiconductor and started lowering its melting point. This was done by mixing zinc with tin and selenium with sulfur. Further they started drilling slots along the surface of the polyethylsulfone material and then inserted the tin zinc wires into the slots.

They made a thin layer of selenium sulfide to deposit on the wires by evaporation process and finally, again wrapped it in polymer. Now a single solid structure had to be formed from this assembly. This was done by heating this assembly in vacuum and then drawing into fiber. As these were drawn into fibers the zinc-tin and selenium-sulfur come together and undergo a reaction. This resulted into crystallization forming small chunks of zinc selenide semiconductor. This led to the formation of the semiconductor diodes which were placed along the length of the fibers on equal distances with tin wires providing electrical contacts."The fact that you can synthesize a high-temperature compound  [zinc selenide] inside a low-temperature matrix is very interesting and surprising, and as far as I know, this is the first time it has been demonstrated in the context of a fiber," says Fink. (As quoted by IEEE Spectrum).

Thus, this method opens the gateways of many other inventions. One day by smart fabric, our T-shirts may power a cell phone!