Technology Hub

Silicon chips stretch into shape

2008-03-28T07:32:00.000-07:00

Normally fragile and brittle silicon chips have been made to bend and fold, paving the way for a new generation of flexible electronic devices.

The stretchy circuits could be used to build advanced brain implants, health monitors or smart clothing.

The complex devices consist of concertina-like folds of ultra-thin silicon bonded to sheets of rubber.

Writing in the journal Science, the US researchers say the chip's performance is similar to conventional electronics.

"Silicon microelectronics has been a spectacularly successful technology that has touched virtually every part of our lives," said Professor John Rogers of the University of Illinois at Urbana-Champaign, one of the authors of the paper.

But, he said, the rigid and fragile nature of silicon made it very unattractive for many applications, such as biomedical implants.

"In many cases you'd like to integrate electronics conformably in a variety of ways in the human body - but the human body does not have the shape of a silicon wafer."

Professor Zhenqiang Ma of the University of Wisconsin-Madison, who also works on flexible silicon circuitry, said the new research was an "important step".

"Completely integrated, extremely bendable circuits have been talked about for many years but have not been demonstrated before," he told BBC News. "This is the first one."

Silicon wave

The chips build on previous work by Professor's Roger's lab.

In 2005, the team demonstrated a stretchable form of single-crystal silicon.

BUILDING BENDABLE CHIPS

1. Plastic sheet is bonded to a rigid substrate with adhesive

2. Complex circuits are built using conventional silicon fabrication techniques

3. Adhesive is dissolved, allowing circuits embedded on plastic sheet to be peeled away

4. Sheet is bonded to pre-strained rubber, creating bendable silicon chips

"That demonstration involved very thin narrow strips of silicon bonded to rubber," explained Professor Rogers.

At a microscopic level these strips had a wavy structure that behaved like "accordion bellows", allowing stretching in one direction.

"The silicon is still rigid and brittle as an intrinsic material but in this accordion bellows geometry, bonded to rubber, the overall structure is stretchable," he told BBC News.

Using the material, the researchers were able to show off individual, flexible circuit components such as transistors.

The new work features complete silicon chips, known as integrated circuits (ICs), which can be stretched in two directions and in a more complex fashion.

"In order to do this, we had to figure out how to make the entire circuit in an ultra-thin format," explained Professor Rogers.

The team has developed a method that can produce complete circuits just one and a half microns (millionths of a metre) thick, hundreds of times thinner than conventional silicon circuits found in PCs.

"What that thinness provides is a degree of bendability that substantially exceeds anything we or anyone else has done at circuit level in the past," he said.

Rubber wrinkle

The slim line circuits, like conventional chips, are made of sandwiches of multiple materials to form the wires and different components. The depth and relative position of the different layers, including chromium, gold and silicon, is crucial.

The silicon circuits can be wrapped around curved surfaces

"You have to design the thicknesses of those materials in such a way that you put what is called the neutral mechanical plane so that it overlaps with the most brittle material," explained Professor Rogers.

The neutral mechanical plane is the layer in a material where there is zero strain.

In a homogenous substance, this plane occurs exactly half way between the top and bottom surface, where there is equal compression and tension as it bends.

This is where the silicon - the most brittle material - is usually positioned, according to Dr Rogers.

"If you locate your circuits there, you can bend your overall system to a very tight radius of curvature, but your circuit doesn't experience any strain," he said.

To create the foldable chips, these circuit layers are deposited on a polymer substrate which is bonded in turn to a temporary silicon base.

In some applications, stretchable and foldable integrated circuits may be the only choice

Zhenqiang Ma

The computing age

Following the deposition of the circuits, the silicon base is discarded to reveal delicate slivers of circuitry held in plastic.

These are then bonded to a piece of pre-strained rubber. When the strain is removed, the rubber snaps back into shape, causing the circuits on the surface to wrinkle accordingly.

"This leads to the wavy geometry that allows the overall circuit system to be stretched in any direction you want," said Dr Rogers.

The complete circuits are still relatively crude compared to top-end computer chips but have typical "silicon wafer performance" for the size of the component, he said.

Brain pad

Other companies and researchers are working on different approaches to flexible electronics.

One approach is to make so-called "organic" electronics, also known as plastic electronics.

These rugged devices are made from organic polymers and have been built into flexible "electronic paper" displays.

The bendable circuits could be used in aircraft or hospitals

However, they are relatively slow and therefore of limited use in high performance devices.

The new work offers an alternative.

"There are many applications," said Professor Ma.

His own work has explored the possibility of using the technology in aircraft, for example building compact antennae or creating 360-degree surveillance applications by embedding chips across the surface of the fuselage.

"In some applications, such a form of stretchable and foldable integrated circuits may be the only choice," he said.

Professor Rogers, working with other scientists, is concentrating on medical applications.

One collaboration seeks to develop a smart latex glove for surgeons which would measure vital signs, such as blood oxygen levels, during an operation.

Another aims to develop a sheet of electronics which could lie on the surface of the brain to monitor brain activity in epileptics.

"Most of our energy is now focused on applications," said Professor Rogers.

New Rocket Technology Could Cut Mars Travel Time

2008-03-28T06:56:00.000-07:00

An agreement to collaborate on development of an advanced rocket technology that could cut in half the time required to reach Mars, opening the solar system to human exploration in the next decade, has been signed by NASA's Johnson Space Center, Houston, TX, and MSE Technology Applications Inc., Butte, MT.

The technology could reduce astronauts' total exposure to space radiation and lessen time spent in weightlessness, perhaps minimizing bone and muscle mass loss and circulatory changes.

Called the Variable Specific Impulse Magnetoplasma Rocket (VASIMR), the technology has been under development at Johnson's Advanced Space Propulsion Laboratory. The laboratory director is Franklin Chang-Diaz, a NASA astronaut who holds a doctorate in applied plasma physics and fusion technology from the Massachusetts Institute of Technology, Cambridge.

Chang-Diaz, who began working on the plasma rocket in 1979, said, "A precursor to fusion rockets, the VASIMR provides a power-rich, fast-propulsion architecture."

Plasma, sometimes called the fourth state of matter, is an ionized (or electrically charged) gas made up of atoms stripped of some of their electrons. Stars are made of plasma. It is gas heated to extreme temperatures, millions of degrees. No known material could withstand these temperatures. Fortunately, plasma is a good electrical conductor.

This property allows it to be held, guided and accelerated by properly designed magnetic fields.

The VASIMR engine consists of three linked magnetic cells. The forward cell handles the main injection of propellant gas and its ionization. The central cell acts as an amplifier to further heat the plasma. The aft cell is a magnetic nozzle, which converts the energy of the fluid into directed flow.

Neutral gas, typically hydrogen, is injected at the forward cell and ionized. The resulting plasma is electromagnetically energized in the central cell by ion cyclotron resonance heating. In this process radio waves give their energy to the plasma, heating it in a manner similar to the way a microwave oven works.

After heating, the plasma is magnetically exhausted at the aft cell to provide modulated thrust. The aft cell is a magnetic nozzle, which converts the energy of the plasma into velocity of the jet exhaust, while protecting any nearby structure and ensuring efficient plasma detachment from the magnetic field.

A key to the technology is the capability to vary, or modulate, the plasma exhaust to maintain optimal propulsive efficiency. This feature is like an automobile's transmission which best uses the power of the engine, either for speed when driving on a level highway, or for torque over hilly terrain.

On a mission to Mars, such a rocket would continuously accelerate through the first half of its voyage, then reverse its attitude and slow down during the second half. The flight could take slightly over three months. A conventional chemical mission would take seven to eight months and involve long periods of unpowered drift en route.

There are also potential applications for the technology in the commercial sector. A variable-exhaust plasma rocket would provide an important operational flexibility in the positioning of satellites in Earth orbit.

Several new technologies are being developed for the concept, Chang-Diaz said. They include magnets that are super-conducting at space temperatures, compact power generation equipment, and compact and robust radio-frequency systems for plasma generation and heating.

Coordinated by Johnson's Office of Technology Transfer and Commercialization, the Space Act Agreement calls for a joint collaborative effort to develop advanced propulsion technologies, with no money exchanged between the two parties. Such agreements are part of NASA's continuing effort to transfer benefits of public research and development to the private sector.

Adobe Debuts Web-based Photoshop Express

2008-03-28T06:45:00.000-07:00

Photo storage on the Web is nothing new. Nor is image editing. But when the two are combined under the mantle of Adobe's Photoshop, well, that unto itself becomes news. Fortunately, Photoshop Express--Adobe's new free, Web-based service that entered public beta today--offers more substance than just the novelty of its heritage.

Photoshop Express may carry the name of Adobe's flagship image editing software, but the online version bears little resemblance to that. Rather, the software tries to make basic editing and enhancing tasks point-and-click easy. My early impressions after using this service: The Photoshop Express beta succeeds in making serviceable image editing available wherever you have an Internet connection, but it stil has bugs and annoyances to eliminate in this shakedown cruise.

The best part about Photoshop Express--beyond its 2GB of free storage hosted by Adobe--is its interface: The graphical, Adobe Air-based user interface is both accessible and attractive. Building a basic slideshow is a snap, and sharing the slideshow is just as simple.

That's not to say this beta doesn't have work ahead--and lots of it. The worst issues I've had so far: My initial hands-on was frought with false starts, including interminably slow upload times (over a robust cable modem connection) and a finicky upload mechanism that rejected 11 out of 15 of the high-resolution images I tried adding to my online album, for no apparent reason (beyond giving an unhelpful upload failed message; I'll be asking Adobe about this issue and update this item when I hear back from them).

Stay tuned for more details about what I liked and didn't like about Photoshop Express in my upcoming review.

Free Online Version of Photoshop Launches

2008-03-28T06:38:00.001-07:00

Thursday Adobe launched Photoshop Express, an free, online version of its popular Photoshop picture and graphics-editing software. In doing so, Adobe joins the crowd of vendors offering online versions of productivity software. Typical of such offerings, Photoshop Express (PE) arrives in beta form.

San Jose, Calif.-based Adobe Systems Inc. says it hopes to boost its name recognition among a new generation of consumers who edit, store and share photos online.

While Photoshop is designed for trained professionals, Adobe says Photoshop Express, which it launched in a "beta" test version, is easier to learn. User comments will be taken into account for future upgrades.

Photoshop Express will be completely Web-based so consumers can use it with any type of computer, operating system and browser. And, once they register, users can get to their accounts from different computers.

Photoshop Express already integrates with Picasa, Facebook, and Photobucket. For now, the beta is U.S.-based. Users can try to login from other countries, but all the servers are in the U.S. so Adobe indicates you'll likely see performance issues.

Gateway P-6831 FX: Best Midrange Gaming Notebook Ever

2008-03-28T06:31:00.000-07:00

Date: March 28th, 2008
Topic: Mobile
Manufacturer: Gateway
Author: Jarred Walton

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Introduction

It's a given fact that computers have been getting smaller since the days of vacuum tubes and ENIAC. What was once a glorified calculator that took up a space the size of a football field can now fit in something the size of your watch. Tasks that used to take months to compute on a mainframe can now be calculated in minutes on a midrange desktop system. Even in a relatively short period of time, we still see progression so that your top-end desktop gaming powerhouse from two or three years ago can be surpassed by a modern laptop.

That's all well and good, but a big problem a lot of people have with gaming notebooks is that their size relative to typical laptops is rather large, making them less convenient to carry around. Relatively short battery life is another drawback. But perhaps the biggest drawback is a very simple one: price.

We recently looked at the Dell XPS M1730, which is arguably the fastest gaming notebook currently available. With its 8800M GTX SLI graphics chips and overclockable Penryn X9000 CPU, you get performance that surpasses most desktops from 18 months ago, or if you prefer a performance that will match a reasonably configured midrange desktop system. If you put together a Core 2 Duo E8400 system with something between GeForce 9600 GT 512 SLI and 8800 GT 512 SLI graphics, you should have roughly comparable performance. The problem is that such a desktop system can be assembled for less than $1500, whereas the powerful XPS M1730 costs about three times as much.

What would be really nice is if we had a viable midrange gaming laptop alternative — something that offers reasonable performance for under $1500. We're not talking about any of the junk shipping with integrated graphics, or low-end stuff like GeForce 8400 or even 8700M GT. How about a laptop with graphics performance that can at least match the GeForce 9600 GT? After all, the 9600 GT can be had for a mere $150 and it doesn't seem to consume that much power; how hard can it be to put something like that into a laptop?

In fact, it's not really all that difficult, and NVIDIA launched exactly that sort of chip in late 2007 with the GeForce 8800M GTS. It has 64 Stream Processors, just like the 9600 GT. Most of the gaming laptops have opted for the more powerful (and more expensive) 8800M GTX with its 96 SPs, so we were quite interested to see exactly how much performance you give up by going with the 8800M GTS. Unfortunately, we can't really do an apples-to-apples comparison here, because Gateway didn't stop at cutting down the GPU. In the system we received, they also trimmed the CPU performance quite a bit, dropping all the way to a 1.66GHz Core 2 Duo T5450. That certainly means CPU performance isn't going to match up well against something like a 2.8GHz X9000; what we want to find out is whether it can still provide adequate performance.

If you've ever looked at buying a gaming notebook, you have likely been very disappointed in the offerings that cost less than $2000. In fact, up until Gateway dropped the P-6831 FX on the mobile gaming market, we honestly haven't seen anything that would even qualify as a good midrange gaming notebook. Gateway didn't just break a $2000 price barrier, however. Available at locations like Best Buy for a mere $1350 (and currently with a $100 rebate), the P-6831 FX completely redefines the midrange gaming notebook. Let's look at how they managed to do this.