Looking like a liquid opal, submicroscopic balls of plastic--the same polystyrene used to make coffee cups--sit embedded in a water-based gel. These polymerized crystalline colloidal array (PCCA) can do amazing and useful things. For instance, University of Pittsburgh chemists John H. Holtz and Sanford A. Asher discovered they can use the PCCAs as chemical sensors to make chemical measurements. "Colloidal arrays have fascinating optical properties," says Asher. "Because of their electrical charge, they self organize into a cubic structure where all the plastic balls are equally spaced. Depending on this spacing, the colloidal array diffracts (or reflects) visible light, much in the same way that an opal does, and you get intense colors." The chemists have made PCCAs that are highly sensitive to particular chemical species or thermal changes. If exposed to certain chemicals, such as lead, the array swells, changing the spacing. That causes the PCCA to diffract light at new wavelengths, and it changes color. Asher's group has demonstrated that the arrays are effective at detecting lead concentrations in water, and that once the lead is cleaned from the array it can be reused without any loss of sensitivity. FAX Kevin Roark at (412) 624-4895.
Science fiction author Isaac Asimov may have the best rules for effective brainstorming and creativity. His never-before-published essay, "On Creativity," recently made it to the Web pages of MIT Technology Review.
Much has been made over the potentially dangerous flammability of lithium-ion batteries after major companies like Boeing, Sony, and Tesla have grappled with well-publicized battery fires. Researchers at Stanford University may have come up with a solution to this problem with a smart sensor for lithium-ion batteries that provides a warning if the battery is about to overheat or catch fire.
In this new Design News feature, "How it Works," we’re starting off by examining the inner workings of the electronic cigarette. While e-cigarettes seemed like a gimmick just two or three years ago, they’re catching fire -- so to speak. Sales topped $1 billion last year and are set to hit $10 billion by 2017. Cigarette companies are fighting back by buying up e-cigarette manufacturers.
Advertised as the "Most Powerful Tablet Under $100," the Kindle Fire HD 6 was too tempting for the team at iFixit to pass up. Join us to find out if inexpensive means cheap, irreparable, or just down right economical. It's teardown time!
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