Archive for the ‘nanotechnology’ Category

Flat-panel ion thrusters

Friday, August 22nd, 2008
You may think spacecraft thrusters need to be big and powerful, but Brian Gilchrist and colleagues at the University of Michigan in Ann Arbor, are thinking small. They propose that tiny "nano thrusters" could be made into flat sheets mounted on the side of spacecraft.

Conventional ion thrusters used for manoeuvring vehicles in space are roughly fridge-sized and work by accelerating gas ions to generate force in the opposite direction. But they waste a lot of gas and are limited in lifetime because the accelerated ions damage the engine.

Their nanothrusters, say the Michigan team, get around these problems. Each consists of a small chamber of fluid with electrodes inside and a vent at the top. Above that vent more electrodes generate a powerful electric field.

The fluid contains nanoparticles just tens of nanometres across that are ionised by electrodes in the chamber. Those charged ions are accelerated by the electric field and ejected from the vent, producing thrust.

These nanothrusters can be used in large numbers on flat panels with micro-scale fuel delivery channels. The panels would cover large areas of spacecraft and in the drag-free space environment give all vehicles fine and efficient control.

The inventors hope the flat-panel thrusters will reduce the cost of spacecraft thanks to their efficiency and light weight, cutting the cost of launching vehicles into space.

Read the full flat panel ion thruster patent.

Justin Mullins, New Scientist consultant

Posted in nanotechnology, space, spacecraft | Comments Off

Nanotube filter

Thursday, May 8th, 2008
Carbon nanotubes are tiny tubes of carbon atoms. When properly formed and lined up, they can be superb conductors or semiconductors, have high thermal conductivity and huge mechanical strength. The versatile structures are touted as being invaluable for everything from space elevators to anti-HIV treatments.

But nanotubes are tricky to control. So far it has only been possible to lay them down at random, which makes exploiting their amazing properties much more difficult.

Now Mary Chan, a chemical engineer at Nanyang Technological University in Singapore has come up with a simple solution.

She suggests suspending the nanotubes in water and passing the fluid through narrow channels. The nanotubes would only be able to pass through the channels if they are aligned with the direction of flow.

When the liquid is drained, the aligned nantotubes settle into place creating a material in which the extraordinary properties of carbon nanotubes can be exploited to the full.

Read the full nanotube filter patent application.

Justin Mullins, New Scientist consultant

Posted in materials, nanotechnology | Comments Off

Printable fuel cell electrodes

Tuesday, March 11th, 2008
Methanol fuel cells that turn fuel and an oxidant directly into electricity without combustion have great potential as power sources for the next-generation of portable devices.

They potentially offer more power from less space compared to today's batteries, and at reasonable cost. However, there are still wrinkles to iron out in the manufacturing process.

The most cost-effective way to make the fuel cells would be to use silicon-based microfabrication, so they are manufactured in the same way as other electronic components. However, the electrodes have to be coated with platinum to catalyse the fuel cell's reactions, and a way of doing that using established processes has proved elusive – until now.

Yushan Yan, a chemical engineer at the University of California, Riverside, US, starts with silver nanowires and uses them as moulds on which to grow platinum nanotubes.
Adding platinum salts to silver nanowires leads to platinum shells forming over them, and the wires eventually dissolving.
The resulting nanotubes offer great efficiency and durability. They can also be sprayed into place using an inkjet printing process, which is compatible with current microfabrication techniques and therefore low cost.

Read the full platinum nanotube electrode patent application.

Justin Mullins, New Scientist consultant

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Toxic onions

Monday, February 18th, 2008
There are plenty of scare stories about health problems caused by nanotechnology, but where does the truth lie? Frank Chen, a researcher at the Lawrence Berkeley National Laboratory, has developed a way to predict and evaluate the effects of exposure to a particular nanomaterial on human skin cells.

Once the skin cells have been exposed, Chen uses computerised image analysis to see whether the cells are dying, and genome analysis to see which genes have been switched on or off.

The method shows that cells are killed by large doses of "multiwall carbon nano-onions" (many-layered versions of spherical carbon buckyballs). In the process, genes involved in cellular transport, metabolism, cell cycle regulation and stress response become activated.

There is an upside, however. Chen suggests that multiwall carbon nano-onions are so toxic that they could be used for killing off cancer cells.

Read the full nanomaterial testing patent application.

Justin Mullins, New Scientist contributor

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