Scientists at Universiti Malaysia Pahang (UMP) have developed displays that can be written on and erased with light. The WORM (Write Once Read Many) display is an optical storage device whose molecular geometry can be altered by shining light on it, allowing information in the form of words or pictures to be impressed on it in as little as 20 seconds. The environmentally-friendly display is also easy to dispose of, the researchers report, as users only have to scratch its surface to remove its protective coating and dip it in water to dissolve it.
The displays are created using highly photosensitive compounds and can be written on using ultraviolet (UV) light. To fabricate the display, the researchers mix the compounds with liquid crystals and create two substrates. Transferring information involves placing a photo mask containing the data on top of the second substrate and exposing it to UV light with a wavelength of 365 nm.
The information on the photo mask is then transferred to the WORM display. Data can be written on the device either permanently or in a manner that allows it to be erased many times, by using separate processes, reportedly making the display suitable for a variety of applications.
"If you consider creating a newspaper optically, then it's possible to print information on the WORM display everyday as it can be automatically erased the next day," Yuvaraj A.R., a researcher on the team, tells Gizmag. "We can reuse the same substrates the next day and thus avoid paper wastage."
Using special compounds, the researchers say, will enable them to create worm displays that erase the stored information after a certain period of time.
"Each compound has its own characteristics," explains Yuvaraj. "The one that we can use for newspapers has properties that cause the stored information to be erased automatically in 30 hours."
To erase information, focused light of sufficient intensity needs to be applied.
"Ordinary sunlight or the light from tube lights are not effective enough to erase the data, so the display is protected," says Dr. Gurumurthy Hegde, the lead researcher.
The displays are stable, the researchers say, as a photo curing glue is applied on top of them to protect them from moisture. When it's time to get rid of a display, users will just have to scratch the surface or cut it to remove the glue. Soaking it in water allows the light-sensitive compounds to dissolve harmlessly. Aside from newspapers, the team reports, the displays could also be used to make name cards, ATM cards, advertising boards, e-books and more.
"You can use WORM displays in schools," explains Yuvaraj." You can write on it with a UV pen and flip a switch that shines light on it to erase a full board instantly."
It's also very inexpensive to fabricate, according to the team; a 3 x 3-ft (0.9 x 0.9-m) display costs around US$45 compared to $700 for traditional advertising displays. Currently the displays are only in black and white, but the team is working towards creating color displays by using cholestiric liquid crystals. The researchers have a fully functional prototype at present and are working towards commercializing the technology.
The WORM display was recently exhibited at the 25th International Innovation and Technology Exhibition (ITEX) at the Kuala Lumpur Convention Center in Malaysia.
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