Nanotube transistor may help humans bond with machines

Thursday, May 13, 2010

London, May 13 (ANI): Scientists in the U.S. have taken a big step toward bridging the gap between the mind and the machine.

Using ATP - adenosine triphosphate, the molecular medium of energy exchange present in nearly all living cells - Aleksandr Noy at the Lawrence Livermore National Laboratory in California and colleagues have created a novel transistor that could allow electronic devices that can be hooked directly into the nervous system.

The new transistor is made up of a carbon nanotube, which behaves as a semiconductor, bridging the gap between two metal electrodes and coated with an insulating polymer layer that leaves the middle section of the nanotube exposed.

The entire device is then coated again, this time with a lipid bi-layer similar to those that form the membranes surrounding our body’s cells.

The team then applied a voltage across the transistor’s electrodes and poured a solution containing ATP and potassium and sodium ions onto the device.

This caused a current to flow through the electrodes - and the higher the concentration of ATP was, the more strongly current flowed.

The device responds in this way because the lipid bi-layer incorporates a protein that, when exposed to ATP, acts as an ion pump, shuttling sodium and potassium ions across the membrane.

“The ion pump protein is an absolutely critical element of this device. Each cycle, it hydrolyses an ATP molecule and moves three sodium ions in one direction and two potassium ions in the opposite direction,” New Scientist quoted Noy as saying.

This results in the net pumping of one charge across the membrane to the nanotube.

The build-up of ions creates an electric field around the exposed portion of the semiconducting nanotube, increasing its conductivity in proportion to the strength of the field. When the supply of ATP is reduced, ions leak back across the membrane and the flow of current through the transistor falls.

Noy has claimed that this is the first example of a truly integrated bioelectronic system.

“I hope that this type of technology could be used to construct seamless bioelectronic interfaces to allow better communication between living organisms and machines,” Noy said.

The study has been published in the Journal Nano Letters. (ANI)

Filed under: Science and Technology

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