Nanoscience study shows that quantum dots 'talk'

Scientists who hope to use quantum dots as the building blocks for the next generation of computers have found a way to make these artificial atoms communicate.

"Essentially, the dots talk to each other," said Ameenah Al-Ahmadi, an Ohio University doctoral student who published the findings with Professor of Physics Sergio Ulloa in a recent issue of the journal Applied Physics Letters.

The dots are tiny, engineered spherical crystals about 5 nanometers in diameter. An average biological cell, in comparison, has a diameter of about 1,000 nanometers. Researchers believe that quantum dots will be extremely useful in developing nanoscale technologies because they are versatile and uniform, which could eliminate possible variations and flaws in materials.

In the recent study, the researchers were the first to use theoretical models to show how light energy shining on quantum dots would prompt them to transfer energy in a "coherent" fashion. They found that when the dots were arranged a certain distance from each other – greater than the radius of the dots – light waves traveled between the nanocrystals in a consistent pattern. In previous research, the light's wavelength would change or become irregular during the energy exchange, which creates a breakdown in communication between quantum dots.

The results suggest that there could be a way to transmit information using light waves, laying the groundwork for a possible optical quantum computer. In this device, light energy would replace the electrical charge currently used to transfer information in conventional computers.

"The idea is to make the (computing) process faster and smaller," said Al-Ahmadi.

The applications of the new quantum dot technology also could include medical imaging. Quantum dots could be injected into the patient, and a device containing more quantum dots could be used to show the position of dots under the skin. Current biology research has had great success with this type of imaging in mouse models, Ulloa said. The dots have fewer side effects than contrast chemicals used in X-rays, and may eventually replace traditional contrast media.

Using light energy instead of electricity also would help keep computer temperatures low, as the light energy does not create as much heat as electrical current, Al-Ahmadi added. ###

The research was funded by the Indiana 21st Century Research and Technology Fund and supplemented by Ohio University's Research Priorities Program. Written by Christina Dierkes.

Contact: Andrea Gibson gibsona@ohio.edu 740-597-2166 Ohio University

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Nano-bots to undertake major tasks?

Mini robots to undertake major tasks? Microrobots jumping onto cell manipulation. From cell manipulation to micro assembly, micro robots devised by an international team of researchers offer a glimpse of the future.

The MICRON project team, led by the Institute for Process Control and Robotics (IPR), Karlsruhe, Germany, brought together eight international partners. Funded under the European Commission’s FET (Future and Emerging Technologies) initiative of the IST programme, MICRON set out to build a total of five to ten micro robots, just cubic centimetres in size.

“Each one would measure about 1.5cm by 3 cm,” says IPR´s Joerg Seyfried. “They were designed to be complete robots, with different kinds of actuators for gripping, cell manipulation, and so on. Each one would be wireless, with lots of electronics on board, and an infrared control system – rather like a TV remote, but two-way in this case. They would be able to cooperate together on a range of tasks.”

Building the robots involved developing many custom applications, he adds. “One of these was the wireless powering system, the ‘power floor’, which allows the robot to get energy from its surroundings,” he says. “It uses a coil system to transmit the electricity through the air.”

The robots were designed as part of a networked system: “The individual robots are not that intelligent,” explains Seyfried. “They don’t, for example, know where they are, although they know which direction they are moving in. We developed a special positioning system, so that we know where each robot is. It views them from 40 to 50 cm above. They are controlled by a central robot control system, with several networked computers for planning and commands – this could theoretically control many robots.”

The hardest part of the project was “getting the hardware integrated and running – our goal was to have five robots operational, but this couldn’t be done in our three-year timeframe owing to the extreme complexity of the task,” he says.

Nevertheless, the one fully functional robot that the project did achieve could be tested in three different scenarios. “The first was a medical or biological application, in which the robot was handling biological cells, injecting liquid into them,” Seyfried explains. “The second scenario was micro-assembly, in which the robot soldered tiny parts. The final scenario looked at atomic force, with the robot mounting atomic force and doing experiments on it.”

The results were encouraging. “Our experiments showed that the cell injection is entirely feasible, as is the micro soldering,” says Seyfried. Although the MICRON robots are clearly not a mass market product, commercialisation – though still far off – would be perfectly possible, he believes: “Robots with this sort of capability, and mobility, would be perfectly suited to lab work, such as the micro assembly of prototypes. Tasks such as cell injection could be performed on a mass scale.”
With MICRON now having run its course, the project team is currently working on the project reports and evaluation. “What’s missing is the integration work, and this is what we will try to do next within the [also FET-funded] I-Swarm project,” says Seyfried. “This will build on MICRON to produce robots with a ‘swarm’ intelligence – that is, with limited capabilities, but able to communicate with each other.”

The tiny robots of science fiction tales might be smarter, but, as Seyfried points out, “We’re working on the smallest size range currently being worked on by a few other groups worldwide – like MIT. On a European level, MICRON is unique.”

Contact: Tara Morris news@istresults.info 322-286-1985 IST Results

Contact: Joerg Seyfried Institute for Process Control and Robotics Universität Karlsruhe (TH) Kaiserstrasse 12 D-76128 Karlsruhe Germany Tel: +49-721-6083656 Fax: +49-721-6087141 Email: seyfried@ira.uka.de

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