Technology Bulletin 23305

Microjets offer on-the-spot chip cooling

The thermal-management-thrust group at Georgia Tech's Packaging Research Center has developed a new and highly efficient cooling technology for on-the-spot and on-demand cooling of individual chips, multichip modules, and electronic packages. The technology, based on dynamic manipulation of miniature single-phase jets using piezoelectric actuators, has been adapted from a research program on flow control supported by the Air Force Office of Scientific Research. Researchers anticipate that the ability to dynamically alter the direction and momentum of these jets should provide an effective means for convective cooling of heated surfaces by controlled jet impingement. Synthesized from the fluid in the system in which they are embedded, the jets offer zero mass flux, obviate the need for external plumbing, and enable operation in closed, sealed modules. For details, contact Group Leader William Z. Black at [email protected].

Digital sensor detects ice, de-icing results

Engineers at Environmental & Process Controls (EPC), Troy, MI, have developed a new concept for digital ice detection. The heart of the system is a flat sensor unit mounted flush with the surface where it is to detect ice, thus becoming part of the surface. This sensor can accurately distinguish between the frozen and melted ice conditions that typically affect aircraft aerodynamic control surfaces, turbine power units, highway bridges and overpasses, car windshields, microwave and communications antennas, and even weather balloons. The system works by taking advantage of the fact that water has a very low resistive impedance and a very high dielectric constant. As water freezes, the resistive impedance rises to a higher level. For more information, FAX EPC President Michael Ciemochowski at (810) 740-1129.

Tiny fingerprint ID system could reduce theft

The half-inch-wide FingerLoc personal fingerprint identification sensor is being touted by its manufacturer, Harris Corp., as the smallest of its kind. It reads fingerprint ridge patterns directly from a finger and sends that data to a processor. OEMs can integrate the sensor into laptop and personal computers, cellular phones, remote-control devices, PC cards, and other such devices. A system using the sensor can quickly identify a user and either allow or prevent access to a device. By controlling access, the FingerLoc sensor could help reduce the theft of such devices as laptop computers, which accounts for $500 million annually in the U.S. For details, visit http://www.authemtec.com/, e-mail Neal Stein at [email protected].

Computer model compensates for measuring-machine errors

A National Institute of Standards and Technology (NIST) computer model that compensates for a common source of error in coordinate measuring machines (CMMs) promises to increase manufacturers' ability to check accurately the shape and dimensions of products. SuperFit software corrects "probe-lobing" errors, a chronic and relatively large source of measurement uncertainty in 98% of the 30,000 CMMs in U.S. factories and labs. Such errors occur due to small variations in the performance of touch-trigger probes, depending on the angle that the probe approaches the part it's measuring. These probes consist of a sensing element and ruby-tipped stylus. They trigger each time they touch the part. When measuring a "perfect" sphere, a typical probe stylus bends, and the tip may move slightly when contacting the sphere at certain angles, causing measurement errors. The SuperFit program maps these errors for a particular CMM and then compensates for them in measuring actual parts. Probe-lobing errors typically are reduced from more than 6 microns to less than 1 micron. Several CMM manufacturers are now evaluating the software. FAX Tyler Estler at (301) 990-7421.

'Smart antennas' to improve wireless communication

Marconi would be amazed. A hundred years after the Italian inventor demonstrated that radio waves can carry information, his "wireless" technology has become the basis for an emerging digital communication system that eventually will let people use a single device to exchange high-quality voice, video, and data messages anywhere, anytime. Playing a key role in this research, Stanford University's "smart antenna" research group is developing a technology to replace the single antennas that are used now in radio and cellular phone systems with arrays of multiple antennas that are connected to advanced signal processors. The simple antenna systems used in current wireless networks send and receive radio waves in all directions. Such systems cannot separate the desired signal from interfering signals on the same channel. Simple antennas also have trouble dealing with multipath signals that scatter off buildings and hills. By processing the signals from several antennas, smart antenna technology can distinguish between desired and undesired signals--even when they're on the same channel. A smart antenna also can combine antenna outputs, such as multipath signals, to improve signal quality. Team leader Arogyaswami J. Paulraj predicts that smart antenna technology could save the cellular phone industry $3 billion over a decade by improving coverage, signal quality, and call capacity. FAX (415) 725-0247 or Circle 656.