piezoelectric
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Tiny thermoacoustic engines pave the way for screaming gadgets
Looks like all that heat generated by your laptop may finally be useful for something other than frying eggs -- a group of grad students led by professor Orest Symko at the University of Utah has unveiled an array of "thermoacoustic" engines that turn heat into sound, which can be directed at a piezoelectric mechanism to produce electricity. The US Army-funded research seems promising but is obviously still in its infancy -- one of the designs the researchers demonstrated is half the size of a penny but pumps out 120dB of noise (about the same as a siren), while another bumped out over 135dB, (which is roughly equivalent to a jackhammer). The team expects that future, smaller designs will work at ultrasonic frequencies outside the range of human hearing. Although we're not expecting hybrid-siren-powered laptops to hit anytime soon, you Utes out there may want to invest in some earplugs -- Professor Symko says they'll be testing these designs at the University's water-heating facility in the next year.[Via InformationWeek]
Shape-shifting paper could help tiny bots take flight
A new breakthrough in materials science may pave the way for those inevitable swarms of tiny flying robots that will one day darken the skies and strike fear into us all, as researchers in South Korea have succeeded in coaxing specially-prepared cellophane paper to rapidly curve and straighten itself in an insect-like flapping motion. Although scientists have apparently known since the 1950's that wood was piezoelectric, meaning that it bends slightly when exposed to electricity, it took a team from Inha University with help from Texas A&M to discover that the same property also holds true for other cellulose-based material. By coating both sides of a sheet of cellophane with thin layers of gold, the researchers were able to create so-called Electroactive paper (EAPap) so sensitive that the voltage from a microwave beam provides enough power to trigger its unique shape-changing abilities. Oddly enough, no one is quite sure of the physics behind the transformation -- theories center around pressure changes resulting from the movement of ions -- but regardless of how it works, we're sure that more than a few governments will be most interested in deploying this technology to beef up their domestic and international surveillance programs.[Via Roland Piquepaille and ScienceNOW]