MIT researchers led by Yoel Fink have developed an optical system made of webs of light-detecting fibers. The meshes are currently able to measure thee light direction, intensity, and phase. The investigators expect that in time the system will be capable of much more, with potential applications ranging from improved space telescopes to clothing that provides situational awareness to soldiers or even the visually impaired.
Stephanie vL Henkel
The fibers, ~1 mm dia., consist of a photoconductive glass core with metal electrodes running along the core's length. The structure is enclosed in a transparent polymer insulator. The spherical configuration allows a web to sense the entire volume of space surrounding it. The sphere can also detect the direction of incoming light by observing its entrance and exit points. Entering light produces a change in current in an external electrical circuit.
The team has also placed two 2D webs in parallel, which can generate rough images of objects placed near them and lit from behind. The images appear on a computer screen as a reconstruction of the distribution of light intensity.
In addition to Fink, the team consisted of John Joannopoulos, Ayman Abouraddy, Mehmet Bayindir, Ofer Shapira, Fabien Sorin, Jerimy Arnold, Dursen Hinczewski, and Yigal Migdal. The work is being funded by the MIT Institute for Soldier Nanotechnologies, the DOE, DARPA, and the NSF. (www.sensorsmag.com/0906/RDLight~)
At China's Harbin University, researchers have created an alcohol detector that requires heating only to 140°C, as opposed to the 300°C for conventional sensors made of zinc oxide. They achieved this by building zinc oxide "nanoflowers" which, because of their large size-to-surface ratio, are exquisitely sensitive to ethanol and undergo a change in resistance in its presence. Each flower consists of bundles of nanorods 15 nm wide. The devices might also prove useful as catalysts.
IOP/Harbin Engineering University
NDT Without Magnets
Southwest Research Institute engineers have developed multilayer thin films and combined them with magnetostrictive sensors to nondestructively detect and monitor defects in aircraft components. The technique, which requires no external magnets, has been successfully demonstrated to be capable of finding a crack in an A-10 aircraft test article and could in principle be applied to commercial craft and pipelines.
Tiny Battery, Big Charge
Tel Aviv University researchers under the direction of Menachem Nathan, Emanuel Peled, and Dina Golodnitsky have developed a fast-charge nanobattery that might protect handheld devices from power source related fire hazards. The nanobattery, measuring ~1 sq. cm, consists of ~30,000 lithium batteries connected in parallel on a 0.5 mm thick nonconducting substrate. It offers the best of both worlds—the internal resistance of a thin-film battery and the high capacity of standard lithium versions. The substrate increases battery charge capacity up to 10 mAh/cm2 . They have been demonstrated good for hundreds of charge/discharge cycles.
What Really Happened
In an effort to put to rest the various conspiracy theories that arose after the World Trade Center towers were attacked, NIST has prepared a fact sheet explaining how it has found no corroborating evidence for hypo-theses suggesting that the towers were brought down by controlled demolition using explosives planted prior to 9/11, or that missiles were fired at or hit the towers. Instead, the document describes how photographs and videos from several angles clearly showed that the collapse initiated at the fire and impact floors, and that the collapse progressed from the initiating floors downward, until the dust clouds obscured the view.