Monday, November 29, 2004

"SENSOR: Embedded sensors gauge materials' inner states"
Sensors developed by Elizabethtown College researchers could pave the way for next-generation materials that would be equipped with 50-ohm coaxial connections that engineers could "ping" to read out the material's internal state. The embedded capacitive sensors could be the cure for advanced processing of materials from carbon nanotube-reinforced composites to plain old concrete, enabling functions ranging from elaborate process control monitoring to simple electronic pop-up alerts that would go the traditional turkey timer one better. "The sensors we make are very small capacitors � I'm talking picofarad parallel-plate capacitors with the material serving as the dielectric. At those frequencies, you don't need much loading to get an effective match to a 50-ohm line," said Nathaniel Hager III, an adjunct professor in the physics and engineering department at Elizabethtown (Pa.) College. Hager performed the work with materials chemist Roman Domszy. A patent was awarded just days ago covering sensing and instrumentation using time-domain reflectometry (TDR) dielectric spectroscopy.
"OPTICAL: Flip-flops push forward era of all-optical computing"
Optical flip-flops could enable a new breed of all-optical chips, from communications switches to full-fledged optical computers, according to the Cobra Research Institute at Eindhoven (Netherlands) University of Technology. Optical flip-flops using light, instead of electrons, to store, process and move data around could eliminate the need for expensive optical-to-electronic-to-optical conversions. Today most semiconductor lasers are on discrete chips, but the Cobra Research Institute claims that the answer may be its ring lasers, fabricated in indium gallium arsenide phosphide. According to the researchers, ring lasers could enable optical signals' use not only for communications but also for memory and processing, thanks to a configuration that enables bistable states � an optical flip-flop. "Two ring lasers are required to form the bistable system," said Cobra researcher Martin Hill. He performed the work with Meint Smit, head of the Opto-Electronic Devices group at the Eindhoven university, and Harm Dorren, for whom Hill works at the Electro-Optical Communications group at Cobra.

Monday, November 22, 2004

"SOLAR: Sun catchers tuned to crank out the juice"
EEs are turning a 19th-century invention into a 21st-century alternative-energy source. The last leg of a two-decades-long effort by the U.S. Energy Deaprtment to unleash superefficient solar power by 2011 is homing in on the so-called Stirling engine, which is being used to drive solar generators. DOE test site measurements suggest the setup could bring the cost of solar power on a par with traditional fossil fuels and hydroelectric sources � assuming the project engineers can balance the separate power feeds from farms of thousands of simultaneously online 25-kilowatt Stirling solar dishes. The heart of the design, the engine itself, was invented by the Scottish minister Robert Stirling in 1816. "The Stirling engine makes solar power so much more efficiently than photovoltaic solar cells can," said Robert Liden, chief administrative officer at Stirling Energy Systems Inc. (Phoenix). "That's because the Stirling solar dish directly converts solar heat into mechanical energy, which turns an ac electrical generator." The bottom line, he said, "is that large farms of Stirling solar dishes � say, 20,000-dish farms � could deliver cheap solar electricity that rivals what we pay for electricity today." Under a multiyear Energy Department contract that started in 2004, Stirling Energy Systems will supply Sandia National Laboratories with solar dishes for integration into full-fledged power-generation substations capable of direct connections to the existing U.S. power grid.

Wednesday, November 17, 2004

"NANOTECH: Smart dust made to 'escort' molecules to sensors"
Researchers have shown recently that magnetic silicon nanoparticles-smart dust-can act as chaperones, surrounding and herding rare sample molecules so that the samples navigate channels to microfluidic sensors without leaving any residue. Someday such chaperones might surround cancer cells and "escort" them to the exit. "When you start talking about samples on the molecular scale, your surface-to-volume ratio is so high that you can't let any [part of the sample] stick to microfluidic channels," said professor Michael Sailor at the University of California at San Diego.

Wednesday, November 10, 2004

"OPTICS: Viscous entrainment builds nanoscale optics"
The extrusion techniques currently used to manufacture thin optical fibers require an aperture of the same diameter as the created cable, but physicists at the University of Chicago believe they have found a better way. With careful process controls that entrain a viscous liquid, a fiber of any nanoscale size can be manufactured without the need to extrude it through a like-sized aperture, the researchers claim. Both hollow and compound optical fibers can be made in a single step, instead of the two steps necessary today. "Entrainment enables a nonviscous liquid to flow through an aperture into a viscous liquid and pull along some of the viscous material to make a long, thin fiber that is smaller than the aperture," said Wendy Zhang, assistant professor of physics at the University of Chicago. "We believe that with careful control of the processing, you can use viscous entrainment to create [either] submicron hollow waveguides or compound fibers with a core that would have a different index of refraction." By adjusting the speed, pressure and viscosity of such a flow, its diameter can be shrunk without limit.
"ANIMAL ON-A-CHIP: Microfluidic chips come alive for medical research"
Microelectromechanical systems researchers are getting close to a complete "animal-on-chip" that would allow medical experiments now requiring live animals to be run in vitro on microfluidic chips. The new approach to medical research is based on housing every type of cell inside a microfluidic circulatory system, which is fabricated using semiconductor equipment. In addition to eliminating animals from experimentation, the new devices use commonly available real human cells that are kept alive in culture. The software and circuitry on the chip provide the cells with the chemicals that enable them to perform as if they were in a living body and built-in sensors constantly monitor cell response in real-time. "We believe the animal-on-chip is not only more ethically palatable than using lab animals, but it will also be more accurate because of its built-in sensors and because we will be using real human cells in our tests," said assistant professor Shuichi Takayama at the University of Michigan (Ann Arbor), whose lab has developed an animal-on-chip.

Monday, November 01, 2004

"BIO-ELECTRONICS: Replaceable Eyeball"
'Bionic eye' builds on prostheses milestones with an implanted artificial sight organ as the goal. Eye-implant technology is fighting a tough battle in the human body. Germs, infections, caustic body fluids, nerve degeneration, toxic reactions to chip-generated heat and the conflicting needs for high speed and ultralow power conspire against it. Nevertheless, scientists worldwide are hard at work on various projects to cure blindness, making it likely that many of these problems will be solved within the next 20 years. Pure medical science also promises solutions within 20 years-specifically, the ability to regress the DNA in dead retinal cells so that they regenerate themselves. Within 10 years, medical science also promises to perfect transplanting living retinal cells harvested from organ bank donors. In case that doesn't happen, the electronics industry is promising prostheses that outperform "original equipment" with every imaginable enhancement-from zooming to infrared to textual annotation and memory augmentation. But before these enhancements can be realized, two huge engineering problems face retinal implants, said Gene Frantz, principal fellow at Texas Instruments Inc. One is their interface to neurons; the other is the heat they generate. "How do you create a wetware interface-how do you connect electronics through the skin and inside the eye without introducing germs, paths for infection and other similar problems?" Frantz asked. "This is not a straightforward microelectronics problem, because you have to mimic biology in order to give the brain a better chance at 'seeing' with an artificial retina," said Mark Humayun, director of the National Science Foundation-sponsored Biomimetic MicroElectronic Systems Engineering Research Center at the University of Southern California. "Everything must be customized so it can mate with neurons-the packaging, the electronics, the software and everything else."