Breakthrough will help embed electronics on plastic sheets

July 24th, 2008 - 4:12 pm ICT by IANS  

Washington, July 24 (IANS) A breakthrough in fabricating transistors from carbon nanotube networks will take electronics a step closer to being embedded on plastic sheets. The advance is likely to permit researchers to use these specialised transistors to create high-performance, shock-resistant, lightweight and flexible integrated circuits at low cost.

Possible applications include an electronic skin that covers an aircraft and automatically monitors the formation of cracks to alert technicians and prevent catastrophic failures.

Its key advantage is that it can be produced at low temperatures, enabling the transistors to be placed on flexible plastic sheets that would melt under the high temperatures required to manufacture silicon-based transistors, he said.

Such shape-conforming electronics are not possible using conventional silicon-based circuits, which are manufactured on rigid wafers or glass plates.

The nanonets are made of tiny semiconducting cylinders called single walled carbon nanotubes. But they have been plagued by a critical flaw. Metallic nanotubes form unavoidably during the process of making carbon nanotubes.

These metal tubes then link together in meandering threads that eventually stretch across the width of the transistor, causing a short circuit.

The breakthrough solves this problem by cutting the nanonet into strips, preventing short circuits by breaking the path of metallic nanotubes.

“This is a fundamental advance in how nanotube circuits are made,” said Ashraf Alam, a professor of electrical and computer engineering at Purdue University.

He is working with Kaushik Roy, also a professor of electrical and computer engineering, and doctoral students Ninad Pimparkar and Jaydeep P. Kulkarni.

Researchers at the University of Illinois led experimental lab research to build the circuits, and Purdue led research to develop and use simulations and mathematical models needed to design the circuits and to interpret and analyse data.

“These findings represent the culmination of four years of collaborative efforts between the Illinois and Purdue groups,” Rogers said. “The work established the fundamental scientific knowledge that led to this particular breakthrough and the ability to make circuits.”

“Other researchers have proposed eliminating the metallic nanotubes,” John A. Rogers, professor of chemistry, said. “Instead, we found a very nice way of essentially removing the effect of these metallic nanotubes without actually eliminating them.”

The researchers created a flexible circuit containing more than 100 transistors, the largest nanonet ever produced and the first demonstration of a working nanonet circuit, Alam said.

These findings were published Thursday in Nature.

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