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Contact Lens Can Detect Glaucoma
Researchers at the University of California created a prototype contact lens that can detect the pressure that builds up in the eye due to glaucoma. Hailin Cong and Tingrui Pan found a way to embed conducting circuits into the substance traditionally used to make contact lenses. To do so, they had to come up with a whole new process.
Normally, the organic polymer used for creating contact lenses and many other items (such as breast implants) is cast-molded into a simple shape. Cong and Pan added a chemical to a solution of the polymer that makes the mixture set when zapped with ultraviolet light. Putting a mask between the mixture and the UV light means only certain parts set; the parts that remain liquid can be washed away. Cong and Pan used a mask to leave the imprint of a circuit on the polymer.
To add electrical conductivity to the mix, Cong and Pan included a solution of silver. The resistance of the substance changes when it is stretched, so the modified polymer can be used for detecting changes in shape such as those that occur in the shape of an eye suffering from glaucoma. While the prototype lens has an opaque sensor, Cong and Pan are hard at work on a transparent lens that could be worn for long periods without impairing vision, to give a continuous read-out of the pressure in the eye.
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Mercedes Preps for No-Petroleum Cars
Most auto makers feature highly efficient hybrids in their line-ups today, and are of necessity researching the use of alternative fuels. But Mercedes-Benz is taking things one step further. According to some reports, by 2015 the company plans to stop selling petroleum-powered cars, and offer automobiles powered entirely by electricity, fuel cells, and/or biofuels instead.
The company already boasts several new power trains. One test vehicle with a new power train that runs on biofuels delivers nearly the same efficiency as a diesel-powered vehicle. The vehicle is expected to be on the market sometime in 2010.
It is projected that this will be followed by the launch of a Smart electric car which is fuel and emission-free. This is consistent with other steps that Mercedes Benz has taken, such as battery improvements and the testing of 100 Smart electric cars in London. The German auto maker plans to invest around $1.4 billion in its long-term Sustainable Mobility plan by 2014. If other auto makers start to follow suit, we could all be driving much cleaner cars and breathing much cleaner air in the next ten or twenty years.
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Nanotube Computing Gets Two Steps Closer to Reality
Carbon nanotubes boast several virtues that make them suitable for use in future computers: they are very small and could potentially replace both conductors and semiconductors in microchips. Unfortunately, to be really useful, scientists need to be able to control what kind they grow (metallic or semiconducting) and make them grow straight. This has proven to be nearly impossible if you grow nanotubes on silicon.
In a paper presented last month at the VLSI Symposium by Stanford's electrical engineering department, the knotty problem of growing straight nanotubes was untangled. As it turns out, if you grow nanotubes on crystalline quartz, and then transfer them to a silicon wafer, you all but eliminate the problem. "If you grow carbon nanotubes on silicon, you will see that the carbon nanotubes are really unruly, like a bowl of thin rice noodles," says Subhashish Mitra, one of the Stanford researchers. "If you use a quartz wafer, the nanotubes are largely aligned with each other. They still have kinks and bends and so on, but they're pretty good."
That leaves the problem of selectively growing either metallic or semiconducting
nanotubes. That issue was addressed by a paper published recently
in Science by Stanford and Samsung chemical engineers Melburne C.
LeMieux, Mark Roberts, Soumendra Barman, Yong Wan Jin, Jong Min
Kim and Zhenan Bao. The trick is to change the substrate on which
the nanotubes are grown. A substrate of aromatic compounds delivers
metallic nanotubes, while one composed of aminosilanes produces
semiconducting nanotubes. Both of these papers provide good news
for chip manufacturers, which are slowly but surely reaching the
physical limits of current materials and techniques.
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