GET TACTILE WITH FOG
You may not have seen them yet, but exhibitors at trade shows are beginning to love the spooky quality of 鈥渇og screens鈥�, which display images on a moving curtain of mist. Soon they will be able go one better, and interact with the images projected on them by pressing their fingers into 鈥渂uttons鈥� in the fog, as if it were a touch screen.
To create a fog screen, cooled water from a ceiling-mounted reservoir is blasted with ultrasound to produce a mist of fine droplets that are funnelled through a slit and guided downwards by fans. Since the droplets are cold they flow obediently and fall to the ground in a smooth sheet, creating a surface upon which images can be projected.
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Now a Finnish company called FogScreen is developing a system that will track a user鈥檚 finger when poked into the screen and use that information to control a computer. How it works is under wraps, however.
LIGHT ON A CHIP
Hybrid microchips that process both light and electric current on a single chip have been developed by Philips and the Kavli Institute of Nanoscience in Delft, the Netherlands.
Conventional chips are made by depositing thin films of semiconductor on a silicon wafer. But the compounds of gallium, indium and arsenic that emit light efficiently usually fail to bond reliably across a whole silicon chip, because of a mismatch between the crystal lattices of the two types of materials.
Chemists in the Dutch team have now discovered that if the patches of the optical compounds are small enough they can be deposited without causing stress problems. So by placing optical elements only where they are needed, instead of across the whole chip, they have been able to make electro-optical circuits, paving the way for high-speed optical computers and internet routers.
UNLEADED GADGETS
First it happened to petrol, now prepare for 鈥渦nleaded鈥� gadgets. The loudspeakers and crystal oscillators used in cellphones, computers and similar devices include many lead-rich materials, such as lead zirconium titanate (PZT), the piezoelectric ceramic used to drive loudspeakers. Now a team of scientists in Japan has invented a range of lead-free materials that match PZT鈥檚 performance. Yasuyoshi Saito and colleagues at Toyota鈥檚 Central R&D Labs, in Nagakute have found that alkaline niobate-based perovskites swell in a similar way to PZT when an electric field is applied.
