A flexible, thermally-activated electronic display made from a mixture of metal nanoparticles and plastic has been created by researchers in Hong Kong.
The paper-like material is easy to make and cheaper than conventional displays that use liquid crystal technology. It could be used in a variety of ways, including electronic billboards and e-books, the researchers suggest.
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Flexible, lightweight and portable displays are already used in a wide range of everyday electronic gadgets, such as mobile phones and digital cameras.
However, most of these displays are based on LCD technology 鈥� liquid crystals combined with polymers 鈥� and this can become very expensive as the size of the display increases.
Now, Weijia Wen and colleagues at the Hong Kong University of Science and Technology have developed a new kind of display that exploits thermochromism 鈥� the ability of a material to change colour as its temperature changes.
Simple construction
鈥淐ompared with traditional displays, our device has a very simple structure and low cost, especially for making large displays,鈥� Wen told New 杏吧原创. 鈥淭his means it could be potentially easier to commercialise.鈥�
The display is just 150 microns thick. It consists of a thermochromic composite containing wires that form a specific pattern, or logo. The wires themselves are made from a mixture of metallic nanoparticles dispersed in a polymer called polydimethylsiloxane (PDMS).
The wire patterns are formed using a standard technique called 鈥渟oft lithography鈥�, and also contain two flexible outstretched electrodes, which are used to control the display.
The patterns on the sheet rapidly change colour, from dark green to white, at temperatures above 60掳C. This temperature can be reached by applying an electric field to the electrodes, causing them to heat up. The colour change can then be reversed by reducing the temperature. The images produced also have unprecedented clarity for thermochromic materials, Wen says.
Roll-up display
鈥淭he display is very thin too, which means that it is lightweight and can easily be rolled up,鈥� says Wen. 鈥淚t also uses less power than a conventional device鈥�.
Wen says the display could be used for outdoor billboards and signs. Electronic books are another possibility, as are 鈥渟mart windows鈥�, which change colour at the flick of a switch.
Another potential application could be making microscopic 鈥渃olour bars鈥�, or temperature monitors, for microchips used to analyse biological samples.
The team hopes plans to further enhance the image quality of the display and to create ones with arrays of 鈥渢hermal pixels鈥� rather than just fixed patterns.
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