The outlook for new technology
Edited by Matthew Miller, Special Projects Editor -- EDN, February 5, 2004
SIGHTINGS
Puff to be cool
Thermal management can cause even the coolest designer to sweat. As ICs get denser and products get smaller and more power-conscious, traditional techniques based on fans and metallic heat sinks may be insufficient or even impractical. To help everybody chill, researchers at the Georgia Institute of Technology (www.gatech.edu) have patented a new technology that reportedly produces two to three times more cooling than the traditional approach and also reduces power consumption by two-thirds.
The synthetic jet ejector arrays, or SynJets, feature a diaphragm mounted in a cavity (Picture). An electromagnetic or piezoelectric driver vibrates the diaphragm 100 to 200 times per second, forcing puffs of air out through openings in the cavity. Although these pulsating jets move 70% less air than a conventional fan of comparable size, they cool more effectively for two reasons, the researchers say. First, they direct the air precisely where it's needed. Second, they create tiny vortices that churn through thermal boundary layers, efficiently mixing the air.
The SynJet modules will scale to fit cramped, low-power products that need cooling but can't accommodate a rotating fan, according to the researchers. Georgia Tech has licensed the technology to Atlanta-based Innovative Fluidics for commercialization.
Solar eclipse
Researchers at Siemens (www.siemens.com) claim to have created organic solar cells that surpass previous generations in efficiency. Laid on foil using a printing process, organic solar cells offer lower weight, lower manufacturing cost, and higher flexibility than silicon-based cells. However, efficiency of only 3% has limited their appeal. The Siemens researchers claim to have achieved 5% efficiency along with service life of several thousand "sun hours." Commercial products based on the advance will arrive in 2005, according to the company.
DSP at light speed
Conceptually, optical computing offers the potential for speed far beyond that of any electronic engine, but practical implementations are few. Israel-based Lenslet (www.lenslet.com) has unveiled an optical DSP that it claims can reach 1012 operations/sec (Picture). The fixed-point design uses an array of 256 VCSELs (vertical-cavity surface-emitting lasers) with 8-bit resolution as electronic-to-optical converters. Their outputs feed an N×N-vector-matrix core, in which 256 SLMs (spatial-light modulators) on a single chip provide simultaneous multiplication. Finally, a column of N light detectors receives the beams from the modulator matrix and drives an array of A/D converters to provide the result vector. By changing the weighting values you store in the SLMs, you can adjust the computed algorithm factors.
A cure for wall warts?
Bulky power adapters are necessary evils for most electronic products. But piezoelectric technology may reduce those ugly "wall warts" to a quarter of their current size or less, according to a Pennsylvania State University (www.psu.edu) researcher. Kenji Uchino and his colleagues have developed a piezoelectric transformer that converts 115V to 15V and then converts from ac to dc to power a notebook computer. Japanese manufacturer Taiheiyo plans to mass-produce the device starting this year. In addition to being smaller than the electromagnetic variety, piezoelectric transformers also produce no heat or EMI, Uchino notes. Eventually, the technology will lead to transformers small enough to integrate directly into products, he predicts.
