News / Science & Technology

Working Computer Built with Carbon Nanotubes

Max Shulaker a graduate student at Stanford University shows off the new material used to make new computers, August 19, 2013, at the Stanford School of Engineering.  ( Photo by Norbert von der Groeben )
Max Shulaker a graduate student at Stanford University shows off the new material used to make new computers, August 19, 2013, at the Stanford School of Engineering. ( Photo by Norbert von der Groeben )

Related Articles

Video IBM Developing Brain-like Computer Systems

The new computers would be very small and use little power, much like the human brain

Microbes Produce Electricity from Sewage

Microbes are as efficient as solar panels, researchers say
VOA News
Researchers at Stanford University may have found the successor to silicon-based microchips.

Using carbon nanotubes (CNTs), a “quirky” material, the team of engineers announced they have built a basic computer. They say the breakthrough has the potential to launch a new generation of electronic devices that run faster, while using less energy than those made from silicon chips.

The Stanford team says their computer has 178 transistors and performs tasks such as counting and number sorting. It runs a basic operating system that allows it to swap between these processes.

CNTs are long chains of carbon atoms that are extremely efficient at conducting and controlling electricity. They are so thin – thousands of CNTs could fit side by side in a human hair – that it takes very little energy to switch them off.

"People have been talking about a new era of carbon nanotube electronics moving beyond silicon," said Subhasish Mitra, an electrical engineer and computer scientist at Stanford in a statement. "But there have been few demonstrations of complete digital systems using this exciting technology. Here is the proof."

Carbon nanotubes have been used as transistors, the on-off switches at the heart of nearly all digital electronic systems, but they have been prone to imperfections, which has made building complex circuits difficult.

Over the years, pressure has been placed upon semiconductors to be smaller and faster. That means shrinking the size of each transistor to pack more of them on a chip. But as transistors become tinier, they waste more power and generate more heat – all in a smaller and smaller space, as evidenced by the warmth emanating from the bottom of a laptop.

Many researchers believe that this power-wasting phenomenon could spell the end of Moore's Law, named for Intel Corp. co-founder Gordon Moore, who predicted in 1965 that the density of transistors would double roughly every two years, leading to smaller, faster and cheaper electronics.

"Energy dissipation of silicon-based systems has been a major concern," said Anantha Chandrakasan, head of electrical engineering and computer science at MIT and a world leader in chip research. He called the Stanford work "a major benchmark" in moving CNTs toward practical use.

In theory, this combination of efficient conductivity and low-power switching make carbon nanotubes excellent candidates to serve as electronic transistors, but inherent imperfections have stood in the way of putting this promising material to practical use.

First, CNTs do not necessarily grow in neat parallel lines, as chipmakers would like.

Over time, researchers have devised tricks to grow 99.5 percent of CNTs in straight lines. But with billions of nanotubes on a chip, even a tiny degree of misaligned tubes could cause errors, so that problem remained.

Another problem is that a fraction of these carbon nanotubes can end up behaving like metallic wires that always conduct electricity, instead of acting like semiconductors that can be switched off.

Since mass production is the eventual goal, researchers had to find ways to deal with misaligned and/or metallic CNTs without having to hunt for them like needles in a haystack.

"We needed a way to design circuits without having to look for imperfections or even know where they were," Mitra said.

The Stanford paper describes a two-pronged approach that the authors call an "imperfection-immune design."

To eliminate the wire-like or metallic nanotubes, the Stanford team switched off all the good CNTs. Then they pumped the semiconductor circuit full of electricity. All of that electricity concentrated in the metallic nanotubes, which grew so hot that they burned up and literally vaporized into tiny puffs of carbon dioxide. This technique eliminated the metallic CNTs in the circuit.

Bypassing the misaligned nanotubes required another method.

The Stanford researchers created a powerful algorithm that maps out a circuit layout that is guaranteed to work no matter whether or where CNTs might be askew.

"This 'imperfections-immune design' [technique] makes this discovery truly exemplary," said Sankar Basu, a program director at the National Science Foundation.

Despite the breakthrough, researchers say industrial-scale production of CNTs is still years away.

The achievement is reported today in an article in the journal Nature.

You May Like

Karzai's Legacy: Missed Opportunities?

Afghanistan's president leaves behind a much different nation than the one he inherited, yet his legacy from 13 years in power is getting mixed reviews More

Video Secret Service Chief Under Fire for White House Security Breach

Julia Pierson faces tough questions from lawmakers after recent intrusion at White House, says: 'It is clear that our security plan was not executed properly' More

Frustrated, Liberian Students Want Ebola Fight Role

Thousands have volunteered to go to counties, rural villages to talk to people in their language about deadly virus More

This forum has been closed.
Comments
     
There are no comments in this forum. Be first and add one

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Malaysia Struggles to Stop People Joining Jihadi
X
Mahi Ramakrishnan
September 30, 2014 2:16 PM
Malaysian authorities say militant groups like the so-called "Islamic State" have used social media to entice at least three dozen Malaysian Muslims to fight in what they call "jihad" in Syria and Iraq. As Mahi Ramkrishnan reports from Kuala Lumpur, counterterrorism police are deeply worried about what could happen when these militants return home.
Video

Video Malaysia Struggles to Stop People Joining Jihad

Malaysian authorities say militant groups like the so-called "Islamic State" have used social media to entice at least three dozen Malaysian Muslims to fight in what they call "jihad" in Syria and Iraq. As Mahi Ramkrishnan reports from Kuala Lumpur, counterterrorism police are deeply worried about what could happen when these militants return home.
Video

Video Could US Have Done More to Stop Rise of Islamic State?

President Obama says airstrikes against Islamic State militants in Syria will likely continue for some time because, in his words, "there is a cancer that has grown for too long." So what if President Obama had acted sooner in Syria to arm more-moderate opponents of both the Islamic State and the Syrian government? VOA State Department Correspondent Scott Stearns reports from the United Nations.
Video

Video Treasure Hunters Seek 'Hidden Treasure' in Central Kenya

Could a cave in a small village in central Kenya be the site of buried treasure? A rumor of riches, left behind by colonialists, has some residents dreaming of wealth, while others see it as a dangerous hoax. VOA's Gabe Joselow has the story.
Video

Video Iran's Rouhani Skeptical on Syria Strikes

Iranian President Hassan Rouhani expressed skepticism Friday that U.S.-led airstrikes in Iraq and Syria could crush Islamic State militants. From New York, VOA’s Margaret Besheer reports the president was also hopeful that questions about Iran’s nuclear program could be resolved soon.
Video

Video US House Speaker: Congress Should Debate Authorization Against IS

As wave after wave of U.S. airstrikes target Islamic State militants, the speaker of the Republican-controlled House of Representatives says he would be willing to call Congress back into session to debate a formal, broad authorization for the use of military force. VOA’s Michael Bowman reports from Washington, where legislators left town 10 days ago for a seven-week recess.
Video

Video Ebola Patients Find No Treatment at Sierra Leone Holding Center

At a holding facility in Makeni, central Sierra Leone, dozens of sick people sit on the floor in an empty university building. They wait in filthy conditions. It's a 16-hour drive by ambulance to Kailahun Ebola treatment center. Adam Bailes was there and reports on what he says are some of the worst situations he has seen since the beginning of this Ebola outbreak. And he says it appears case numbers may already be far worse than authorities acknowledge.
Video

Video Identifying Bodies Found in Texas Border Region

Thousands of immigrants have died after crossing the border from Mexico into remote areas of the southwestern United States in recent years. Local officials in south Texas alone have found hundreds of unidentified bodies and buried them in mass graves in local cemeteries. Now an anthropologist and her students at Baylor University have been exhuming bodies and looking for clues to identify them. VOA’s Greg Flakus has more from Waco, Texas.
Video

Video Ebola Robs Liberians of Chance to Say Good-Bye to Loved Ones

In Liberia, where Ebola has killed more than 1,500 people, authorities have worked hard to convince people to allow specialized burial teams to take away dead bodies. But these safety measures, while necessary, make it hard for people to say good bye to their loved ones. VOA's Anne Look reports on the tragedy from Liberia.
Colonel Steve ‘Spiros’ Pisanos left Greece and came to the U.S. to learn to fly. He flew fighters for the Allies in World War II, narrowly escaping death multiple times.Colonel Steve ‘Spiros’ Pisanos left Greece and came to the U.S. to learn to fly. He flew fighters for the Allies in World War II, narrowly escaping death multiple times.

AppleAndroid