A candidate to be the next-generation atomic clock is based on the heavy metal strontium and uses a laser lattice to suspend super-cooled atoms. The result was a 430-THz time base—40,000 times faster than the current 9.19-GHz cesium-based atomic clocks. The strontium-based clock was demonstrated recently by the Commerce Department's National Institute of Standards and Technology (NIST) with help from the University of Colorado at Boulder and JILA (formerly the Joint Institute for Laboratory Astrophysics).
Thursday, November 30, 2006
Monday, November 27, 2006
While microfluidic devices that enable such popular applications as laboratories-on-a-chip are still mostly in the research stage, some companies are making strides toward commercial-grade applications. Microfluidics enables chips to pipe fluids around their surfaces in micron-sized channels, either to perform a test hitherto only possible in a lab, or just to remove heat and cool a chip. The premiere application--labs-on-a-chip--enables battery-powered sensor-based devices to quickly detect trace amounts of almost any substance. What are the blocks to volume production today? That depends on whom you ask, but three reasons loom large--a lack of chip-sized microfluidic pumps; a mismatch between micro-sized fluidic channels and the rest of a lab's equipment; and a lack of standards for interoperability among labs-on-a-chip from rival manufacturers. The first problem--a lack of chip-sized microfluidic pumps--was addressed recently by two new architectures for micropumps (see page 34). One from the University of Utah uses a "squeeze bottle" approach that houses the micropumps in a disposable polymer test card. The other from the Massachusetts Institute of Technology (Cambridge, Mass.) uses a novel photolithographic technique to gain electronic control over micropumping.
For a soldier in the field, a slight hand tremor, tic of the eye, sudden sore throat or whiff of a noxious odor could urgently put his battery-powered portable lab to work. Such microfluidic labs-on-a-chip could let soldiers test their own blood for exposure to many toxins simultaneously and in a matter of minutes. At least, that was the goal of a professor at the Massachusetts Institute of Technology when he landed a U.S. Army contract to pursue work on the tiny tool. Although commercially available "gene chips" can test blood for thousands of toxins simultaneously, it takes hours to diffuse a blood sample across the whole array and then scan for fluorescence. Laboratory high-voltage power supplies could speed the operation with the pumping action of an electric field, but a battery-powered device could not supply that much juice. Enter an MIT mathematician with friends in the engineering school and funding from the Army's Institute for Soldier Nanotechnologies has solved the problem with a low-voltage micropump. A new company, ICEO Technologies Inc., will commercialize the micropump technology.
Laboratories-on-a-chip pack the punch of an overnight testing facility, but get results in minutes by virtue of nanoliter-size chambers that speed up chemical reactions. Of the dozens of kinds of micropumps that can be used to fill those chambers, only a few avoid contaminating the nanoliter-size samples. Recently the University of Utah showed a design that avoids contamination via the use of vacuum-driven, plastic layered membranes. The beauty of the University of Utah design is that a tester the size of a deck of cards could contain hundreds or thousands of independent chambers, each prefilled with the reagents for an array of tests. Then, all the chambers could be supplied with the sample to be tested simultaneously, using nothing more that a battery-powered air pump. A reader no bigger than a deck of cards would accept blank, credit-card-size test cards. Its chambers would be filled with a sample from the patient, and the results of the test would be read out in minutes. After testing, the disposable card would be thrown away. Currently, patients have to wait overnight for a traditional medical lab to do the evening's batch run.
Posted by R. Colin Johnson at 12:00 AM
Wednesday, November 22, 2006
What with the Bluetooth headset crowd wandering the streets talking to the air, you might have thought the final tether to land lines had already been cut. You would be wrong. At least two vital functions have yet to be loosed: network routers, which must always be on and thus cannot be battery-powered, and the chargers for all those batteries powering the world's wireless network nodes, cell phones and laptops. Now developers and researchers are getting out the wire cutters. With half a dozen companies already touting battery-powered mesh networks as replacements for dedicated, wired routers in industrial and field environments, observers predict the technology will work its way into the mainstream. And researchers at the Massachusetts Institute of Technology are perfecting a technology that they say could recharge batteries wirelessly--and perhaps eliminate batteries altogether--by harnessing omnidirectional wireless power beacons
Posted by R. Colin Johnson at 3:45 PM
Monday, November 20, 2006
Dust Networks Inc. (Hayward, Calif.) last week unveiled the world's first system-on-chip (SoC) for wireless sensor networks at Electronica in Munich, Germany. By integrating hardware and software functions to put distributed sensor networks on a single chip--called mote-on-chip--Dust Networks claims 5x lower power consumption than ZigBee, the elimination of the need for wired routers and a tenfold reduction in the overall price of adding new sensors to an existing network. Wireless sensor networks enable industrial users with distributed process control problems to quickly deploy new sensors without having to run cables to them, reducing their overall cost from thousands to hundreds of dollars. Emerson Process Management has launched a family of low-power wireless sensor networking systems that use Dust Networks' Time Synchronized Mesh Protocol (TSMP), including temperature sensors, pressure sensors, fluid-level sensors and fluid-flow sensors. British Petroleum (BP), Emerson's beta tester, now says that going wireless has reduced the cost of adding new sensors by 10x.
The hurdles to wireless power transfer through space have been perceived to be so great that the last serious work on the topic, reported in the 1920s, was inspired by Nikola Tesla's seminal demonstrations circa 1890. But now an MIT physicist claims the obstacles to wireless power transfer are surmountable, at least for distances under 12 feet. Nonradiative resonant energy transfer harnesses omnidirectional energy beacons without wasting energy, without requiring a clear line of sight and without damaging obstacles in the process. Power from such energy beacons would pass harmlessly through everything but their intended targets, by virtue of resonant power antennas that would be tuned to the power beacon's frequency in a lock-and-key approach.
Tuesday, November 14, 2006
Researchers are claiming that the obstacles to wireless power transfer can be overcome—at least at distances up to 12 feet. The Massachusetts Institute of Technology announced the development of wireless power beacons on Tuesday (Nov. 14) at the American Institute of Physics' Industrial Physics Forum in San Francisco. MIT claims that historical obstacles to wireless power transfer through space are surmountable, and perhaps enable the wireless recharging of batteries. Called "nonradiative resonant energy transfer," the technique harnesses omnidirectional energy beacons without the requirement for unobstructed line-of-sight. The technique wastes no energy and is eco-friendly, MIT claimed. In MIT's scheme, power from energy beacons would pass through everything but their intended targets by virtue of resonant power antennas tuned to the power beacon's frequency, ensuring that little energy is lost or would adversely affect the environment.
Posted by R. Colin Johnson at 6:20 PM
Microelectromechanical system (MEMS) startup Discera Inc. said it is teaming with quartz crystal oscillator maker Vectron International Inc. to develop MEMS oscillators. Discera (San Jose, Calif.) said it will supply the MEMS resonator while Vectron (Hudson, N.H.) adds an ASIC containing a phase-locked loop (PLL) and conditioning circuitry. The result, the partners said at the Electronica exhibition this week in Munich, Germany, is the first MEMS oscillator from a quartz crystal oscillator maker.
Posted by R. Colin Johnson at 2:35 AM
Monday, November 13, 2006
Converting from optical to electrical signals, then back to optical, is the bane of modern networks, often requiring a $10,000 optical-to-electronic converter just to perform some simple signal processing, then another $10,000 electronic-to-optical converter to put the signal back on the fiber-optic cable. Now researchers have invented a method that merges electronics with optics by inserting semiconductor devices inside a hollow optical fiber, potentially integrating the electronic signal-processing functions into the cable carrying the signal. The technique coats the inside of the hollow cores of fiber-optic cables with semiconductors at a rate of tens of nanometers per minute. At the end of the process, the hollow cores--which may measure 100 nm to 5 microns in diameter--close down to as small as 10 nm. So far the researchers have successfully fabricated silicon germanium heterojunctions inside a fiber, demonstrated that the fiber still behaves as a waveguide, then implemented a field-effect transistor (FET) that could modulate the signal passing though the core.
Monday, November 06, 2006
A research group at the State University of New York at Buffalo has announced a promising technique in spintronics that might be used in standard silicon chips in the near future. Spintronics combines today's charge-based data storage and communication with magnetic-based information using spin as the common coin. The experimental group has managed to inject electrons with spin into silicon chips by virtue of a ferromagnetic semiconductor junction with silicon. Spintronics marries electronics to magnetism by encoding electronic data with magnetic spin. Theorists recommend using techniques that have already been proved with gallium arsenide semiconductors to inject electrons with spin into silicon circuits. Their cookbook proposes techniques for spin injection and detection in silicon with colleagues at the U.S. Naval Research Laboratory. The researchers predict that the most promising technique, called the spin-voltaic effect, will bring spintronics to standard silicon chips within a year. They have already cast his spin-voltaic effect into experimental gallium arsenide chips and plan to have silicon devices working by 2007.
In experiments, biofuel cells have harnessed membranes of living bacteria to separate anode from cathode--enabling them to share an electrolyte chamber like a lead-acid battery. Now, researchers at the Pacific Northwest National Laboratory have purified the essential protein performing a fuel-cell membrane's electronic function, clearing the way to commercialize biofuel cells sans bacteria. The team purified the bacterium down to the essential protein in the cell wall--eliminating the need to keep the bacterium alive. The only missing element was a fuel source, which biomass could supply, lab scientists reasoned. Now they propose biofuel cell arrays to harvest biomass in tiny reactors. The reaction creates a mobile electron carrier that shuttles electrons to the protein-coated electrodes, generating electricity as it neutralizes the biomass. The proposed biofuel cells would use a cheap porous hematite electrode in which the bacteria's purified protein could be bound. The coated electrodes would catalyze the reaction, enabling electricity to flow from the anode to the cathode using nothing more than the biological agents in the biomass as fuel.