Blue Waters and Petascale Computing

The Blue Waters project will build the world’s first sustained petascale computational system dedicated to open scientific research. The project will include intense support for application development, system software development, interactions with business and industry, and educational programs. This comprehensive approach will ensure that users across the country will be able to use Blue Waters to its fullest potential. Read more

New kind of transistor radios show capability of nanotube technology

Carbon nanotubes have a sound future in the electronics industry, say researchers who built the world’s first all-nanotube transistor radios to prove it.

The nanotube radios, in which nanotube devices provide all of the active functionality in the devices, represent “important first steps toward the practical implementation of carbon-nanotube materials into high-speed analog electronics and other related applications,” said John Rogers, a Founder Professor of Materials Science and Engineering at the University of Illinois. Read more

Ultrasonic frogs can tune their ears to different frequencies

In research that likely has implications for creating intelligent hearing aids, researchers have discovered that a frog that lives near noisy springs in central China can tune its ears to different sound frequencies, much like the tuner on a radio can shift from one frequency to another. It is the only known example of an animal that can actively select what frequencies it hears, the researchers say.

The findings, from a collaborative effort led by the University of Illinois and the University of California at Los Angeles, appear this week in Proceedings of the National Academy of Sciences. The research team also included scientists from the Chinese Academy of Sciences and the Massachusetts Eye and Ear Infirmary (at Harvard Medical School).

The discovery was made when researchers examined the eardrums of an unusual frog, Odorrana tormota, which communicates by making birdlike calls in the audible and ultrasonic frequency ranges. Previous research by two of the authors showed that the frog produces and responds to ultrasonic calls. In the new study they sought to determine whether the frog’s eardrums actually vibrate in response to these ultra high frequency sounds.

Using a laser vibrometer to measure the eardrum’s vibration, the researchers found that the eardrum did respond to sounds in the sonic and ultrasonic ranges. But they also saw something they couldn’t explain: The eardrum’s sensitivity to ultrasound sometimes disappeared altogether.

Normally sound waves strike the eardrum and – if they are powerful enough and in a frequency range that the animal can perceive – cause the eardrum to vibrate. In most studies of frogs, the eardrum responds exactly the same way to the same sound stimulus. Even the eardrums of a dead frog will respond with unchanging predictability.
Past research showed that a frog’s eardrum never responds differently to the same sound stimulus, said team leader Albert Feng, a professor of molecular and integrative physiology at Illinois.

“This was contrary to everything that we knew about its auditory system,” he said.

O. tormota, the concave-eared torrent frog, is unusual in other ways. Most frogs have ears on the body surface, but the torrent frog’s ears are recessed. Feng and his colleagues previously reported that O. tormota communicates in a noisy environment by emitting high frequency calls that include ultrasonic sounds, and can localize sound with astonishing precision. Upon hearing a female call, a male will leap directly toward the sound with an error of less than 1 percent, a feat previously unheard of in frogs.

Fortunately for the researchers, the eardrum of O. tormota is transparent, offering a view of its inner workings in a living frog.

While puzzling over the peculiar results of the eardrum vibration measurements, the researchers noticed the sudden appearance and disappearance of a dark shadow on the eardrum, Feng said.

Further investigation revealed that the frogs were actively opening and closing their Eustachian tubes, the two narrow channels that connect either side of the pharynx to the left and right middle ear. The changing state of the Eustachian tubes was more readily observed by directing a light beam at the mouth from under the frog’s chin. When the Eustachian tubes were open, the light was visible through the eardrum. When they closed, the circles of light glowing out through the ears disappeared. (See movie.)

“We said, ‘Whoa! This is bizarre!’ ” Feng recalled. “In all textbooks on sound communication and hearing in frogs, it is plainly stated that the Eustachian tubes are permanently open!”

Feng and his colleagues had observed that when open, the Eustachian tubes essentially couple the frog’s left and right ears. This “acoustic coupling” between the ears makes them sensitive to sound direction, enabling the frog to localize sound, Feng said.

To determine the consequence of active closure of the Eustachian tubes, the researchers measured how the open and closed Eustachian tubes affected the vibration of the eardrum.

They found that the frogs’ eardrums became very sensitive to high frequency and ultrasounds when their Eustachian tubes were closed, compared with when they were open. When the Eustachian tubes were open, the eardrums responded mostly to low frequency sounds.

The frogs appear to be able to tune in to specific sound frequencies at will, Feng said. They can shift to high frequency and ultrasonic hearing when the low frequency background noise of rushing water is too intense for them to pick out the calls of potential mates or rivals, he said.

Stretchable silicon camera next step to artificial retina

CHAMPAIGN, Ill. — By combining stretchable optoelectronics and biologically inspired design, scientists have created a remarkable imaging device, with a layout based on the human eye.

As reported in the Aug. 7 issue of the journal Nature, researchers at the University of Illinois and Northwestern University have developed a high-performance, hemispherical “eye” camera using an array of single-crystalline silicon detectors and electronics, configured in a stretchable, interconnected mesh.

The work opens new possibilities for advanced camera design. It also foreshadows artificial retinas for bionic eyes similar in concept to those in the movie “Terminator” and other popular science fiction.

“Conformally wrapping surfaces with stretchable sheets of optoelectronics provides a practical route for integrating well-developed planar device technologies onto complex curvilinear objects,” said John Rogers, the Flory-Founder Chair Professor of Materials Science and Engineering at Illinois, and corresponding author of the paper.

“This approach allows us to put electronics in places where we couldn’t before,” Rogers said. “We can now, for the first time, move device design beyond the flatland constraints of conventional wafer-based systems.

The camera’s design is based on that of the human eye, which has a simple, single-element lens and a hemispherical detector. The camera integrates such a detector with a hemispherical cap and imaging lens, to yield a system with the overall size, shape and layout of the human eye.

To make the camera, the researchers begin by molding a thin rubber membrane in the shape of a hemisphere. The rubber membrane is then stretched with a specialized mechanical stage to form a flat drumhead.

Next, a prefabricated focal plane array and associated electronics – created by conventional planar processing – are transferred from a silicon wafer to the tensioned, drumhead membrane.

When the tension is released, the membrane returns to its original shape. This process compresses the focal plane array, causing specially designed electrical interconnects to delaminate from the rubber surface and form arcs, pinned on the ends by detector pixels. These deformations accommodate strains associated with the planar to hemispherical transformation, without stressing the silicon, as confirmed by mechanics modeling performed by researchers at Northwestern.

The array package is then transfer printed to a matching hemispherical glass substrate. Attaching a lens and connecting the camera to external electronics completes the assembly. The camera has the size and shape of a human eye.

Over the last 20 years, many research groups have pursued electronic eye systems of this general type, but none has achieved a working camera.

“Optics simulations and imaging studies show that these systems provide a much broader field of view, improved illumination uniformity and fewer aberrations than flat cameras with similar imaging lenses,” said Rogers, who also is a researcher at the Beckman Institute and at the university’s Frederick Seitz Materials Research Laboratory.

“Hemispherical detector arrays are also much better suited for use as retinal implants than flat detectors,” Rogers said. “The ability to wrap high quality silicon devices onto complex surfaces and biological tissues adds very interesting and powerful capabilities to electronic and optoelectronic device design, with many new application possibilities.”

Intel, HP, Yahoo and Illinois announced Cloud Computing Initiative

In collaboration with Hewlett-Packard, Intel, and Yahoo!, Illinois will develop an experimental testbed for data-intensive applications using distributed “cloud” computational resources. The global partnership, which also includes the National Science Foundation (NSF), the Read more