Much Faster Nanoscale Flexible Circuits Developed

Nanoscale flexible circuits, which could be used in foldable devices, integrated in clothes, or used in satellites for their low weight, have been developed by Stephen Bedell and Davood Shahrjerdi at IBM's Thomas J Watson Research Center in Yorktown Heights, New York.

In order to be flexible, the circuits are very thin - 10,000 times thinner than a piece of paper - which was possible by peeling them off of a silicon wafer and put onto plastic - an industry first. Since the circuits are essentially the same as "conventional" chips on silicon, they are also as fast as those chips, and have features like integrated memory cells, which is the difference to other approaches to make flexible circuits.

These circuits are also easily transferrable at any size, arbitrary in shape, and compatible with any flexible substrate. With a possible radius of curvature of only 6 mm, these sheets of circuits could cover or roll on top of almost anything.

"In certain applications such as space satellites and portable consumer electronics, weight of onboard devices is the key factor. Thin flexible circuits are so light that a large number of these circuits can be stacked to provide unprecedented computing power," said Bedell.

The two scientists used the Controlled Spalling Technique to create the flexible circuits, which can be applied to other materials as well. For instance, Controlled Spalling could also be used to replace the poor thermal conducting sapphire substrate on solid state lighting.

In this application the light (and heat) generating layers can be removed from the sapphire and mounted onto a higher thermally conducting material, such as metal.

These flexible chips have still the same capabilities as the chips still sitting on the silicon wafer on which they were manufactured. In the demonstrated example, more than 10 billion transistors can sit on the plastic substrate. Their low power needs - just 0.6 volts - also make them perfect for novel mobile applications, wearable electronics and bioelectronics.

"For example, in healthcare, a physician could implant a self-powering flexible electronic chip comprised of many nanoscale silicon-based devices into a patient to deliver drugs, or provide analysis via something like a bluetooth signal" said Shahrjerdi.