A team from the University of Alberta has proven for the first time that a single molecule can switch electrical currents off and on, a puzzle that scientists worldwide have been trying to crack for decades.

The finding could revolutionize the field of electronics, providing a leap ahead for everything from computers to batteries to medical equipment.

“We’ve made a tiny, tiny, maybe the ultimate tiniest transistor,” said Robert Wolkow, a physics professor and the principal investigator who headed the research team from the National Institute for Nanotechnology at the U of A.

“This has been a key goal of researchers in this field for nearly 20 years and we have done it. … Molecular electronics are indeed possible, no longer just a futuristic theory.”

His research, to be published in today’s edition of the scientific journal Nature, shows that a molecular transistor can be made to control electricity at a minuscule level.

While a computer using this new technology is at least a decade away, Wolkow said his team’s discovery could eventually mean computers will run much faster using only one-millionth the power of conventional computers.

“That’s a dream scenario but I don’t see why it couldn’t one day be true,” Wolkow said.

With a $1-million scanning tunnelling microscope that spits out images onto a computer screen, Wolkow, together with post-doctoral fellow Paul Piva and others, showed that a single atom on a silicon surface can be controllably charged, while all surrounding atoms remain neutral. When a molecule is placed close to that atom, it becomes a highway that transmits the current from one surface to another.

That molecule is so tiny it can only be measured on the scale of nanometres — billionths of a metre.

“Our work defines the state of the art,” he said.

Transistors control electrical currents and act as off-on switches in everything from traffic lights to washing machines. “Because we achieved the switching with one electron — instead of a million electrons as in today’s smallest, fastest transistors — we have the expectation that we can run these things with a million times less power. Imagine the power savings, and it takes less time.”

So efficient is this potential new technology, said Wolkow, that “the question now about the battery life in your laptop would go away. Your battery today would run your computer all week or all month instead of three to four hours.”

Not only that, but because the microelectronics could eventually be made out of molecules, some computer parts could be biodegradable since molecules can be broken down into small bits.

“You could sort of rinse away a broken computer and let bacteria eat up the remains to be composted,” Wolkow said. “We’re hoping it’s a very green technology. Not only because it could use a million times less power, but it clearly would be greener in the sense that it would just use less material.”

Building such a computer would be wildly complex and long distant, since computers have millions of tiny transistors inside them. Wolkow said it’s more likely the new technology could be used sooner in fairly simple medical diagnostic sensors, perhaps carried around by doctors. Wolkow said such a sensor might be able to detect certain molecules that indicate a malady in someone. If the molecules are present, a tiny light might blink on, Wolkow said.

By Jodie Sinnema

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