For years, researchers have been building tiny nanobots that could one day serve a variety of purposes. But, until now, nanobots couldn't work together.

Recently, scientists Anirban Bandyopadhyay and Somobrata Acharya from the National Institute of Materials Science in Tsukuba, Japan, have built the first ultra-tiny, ultra-powerful "brains" for nanobots.

The brains - just two billionths of a meter across - act as tiny computer transistors. But instead of carrying out just one operation at a time, like a normal transistor, the new devices can simultaneously perform 16 operations at once. In other words, the devices use parallel processing - like the human brain - rather than serial processing - like a normal computer. The researchers call this ability "one-to-many" communication.

The tiny machines are composed of 17 duroquinone molecules that act as logic gates. The researchers arranged 16 of these molecules in a wheel, and placed the last molecule in the middle, which acts as the control center. The entire wheel was constructed on a gold substrate.

Each duroquinone molecule has four side chains that can be independently rotated to represent four separate logic states. Conventional transistors, on the other, have just two logic states: on and off.

To operate the device, the researchers poked the center duroquinone molecule with electrical pulses from the tip of a scanning tunneling microscope. The center molecule is linked to the surrounding 16 molecules by weak hydrogen bonds, so that a pulse to the center molecule can simultaneously transmit instructions to each of the surrounding molecules.

Since each molecule has four side chains, a single pulse to the center molecule can produce one of nearly 4.3 billion (4^16) different states. That compares with a total of 2 (2^1) states that can be produced in a conventional transistor. However, some instructions from the center molecule result in particular arrays of molecules that take on fixed states to maintain equilibrium. But, in principle, the system has 4.3 billion possible states.

Banyopadhyay and Acharya aren´t stopping there, though. The team plans to turn the 2D wheel of 16 molecules into a 3D sphere - a structure that would consist of 1,024 molecules. This spherical device could perform 1,024 instructions at once, theoretically making it capable of 4^1024 different states. The center molecule could be controlled with "handles" that stick out of the core.

The researchers also tested out the 2D nano-brain in their study. They attached the device to eight nanobots (sometimes called "molecular machines"), and demonstrated that the nanobots could respond simultaneously to a single instruction. The ´bots could work together, as if part of a tiny factory.

The scientists also created the "world´s tiniest elevator," a 2-nanometer-tall device that can move up and down by 1 nanometer. They also plan to hook up the brain to a variety of nano-sized motors, propellers, switches, and sensors for different applications.

In the future, the researchers hope that they can control the central duroquinone molecule using proteins or other molecules, rather than the scanning electron microscope tip. For one thing, this ability might enable the brains to serve as tiny transistors packed onto a microchip for future powerful computers.

More futuristically, the brains could accompany nanobots for medical missions, such as bloodless surgery. As the scientists explain, specialized molecular machines could travel through veins to a tumor or damaged tissue, and perform surgery according to the instructions given by the new brains.

More information: Bandyopadhyay, Anirban and Acharya, Somobrata. "A 16-bit parallel processing in a molecular assembly." Proceedings of the National Academy of Sciences. March 11, 2008, vol. 105, no. 10, 3668-3672.

[link to www.physorg.com]


===============

Molecular computer could be 'nanobot brain'

A molecular machine has been devised as the potential brain of "nanobots" now under study for uses in medicine.

The device can handle 16 times more instructions at a time than conventional computer chips.

"This project is part of a massive brain building project, and this is first success towards this end," says Dr Anirban Bandyopadhyay, National Institute of Material Science, Tsukuba, Japan.

The discovery could provide a way to control many molecular machines simultaneously, increase computer processing power, and perhaps keep Moore's Law alive - the doubling in number crunching power every two years that some feared was running up against problems in squeezing ever more components in ever smaller areas.

With Somobrata Acharya, Dr Bandyopadhyay describes in the Proceedings of the National Academy of Sciences how they developed a processor made up of 17 molecules of the chemical duroquinone, which has four side chains that can be independently rotated to represent four logic states: 0, 1, 2, and 3.

This contrasts with conventional microchips, which essentially have two logic states: on and off.

One duroquinone molecule sits at the centre of a ring formed by the remaining 16, and its state is controlled and switched by a scanning tunnelling microscope, which has an ultrasharp tip that can not only program the molecular computer but take an image of the molecules, to confirm decisions made by them.

From the change in contrast on screen, he can distinguish the logic states, the "bits" of the machine. "Brightest one is state three, and state 0 is the darkest in the image," he says.

By changing the central molecule's state, the team could potentially instruct the other molecules in four billion ways. "This is fully experimental work, we have practically realised it," he adds, explaining that for this to be used in a real environment to execute a series of tasks the central molecule will have to be programmed by a protein.

The researchers note that the design is inspired by the massively parallel communication of cells inside a human brain. If this one-to-many computation can be scaled up to large molecular complexes, a fast and efficient parallel signal processing system could be established.

Dr Bandyopadhyay said the molecular machine is built to function as a control unit for medical nanobots. "In future, there will be no medical surgery to destroy tumours, or revive structure of damaged brain, and so on.

"Doctors will inject molecular machines attached to similar control unit, the assembly will go to the target part inside our body through veins, and carry out bloodless surgery. Till now several molecular machines have been built, prior to this work, but there were no machine that could control them."

In existing supercomputers, a job is divided into multiple tasks and each one is executed in separate processors parallel, but no processor can influence the decision of other machines at the same time.

"Therefore, the concept of truly parallel computer operation requires a unique design where one processor must influence others at the same time as making a decision. And that's where this concept is unique. As the molecules are arranged in a wheel pattern, by changing the wheel at the centre one changes all the surrounding ring molecules simultaneously.

"Therefore, success of this machine assembly originates from the circuit connection itself. Linear connection of processors always leads to sequential processing, but these radial connections could be the key for massively parallel and robust supercomputing in the future," he says.

[link to www.telegraph.co.uk]