Micro-robots for micro-manufacturing
An EU-funded consortium has built tiny robots capable of handling objects less than 100nm in size, as part of an effort to develop tools for manufacturing nanoscale devices.
The group, called NanoHand, has built two micro-robotic demonstrators that can automatically pick up and install carbon nanotubes. Thousands of times thinner than a human hair, carbon nanotubes are rolled up sheets of carbon just a few tens of nanometres in diameter, and they could become an essential part of the nanotechnologist’s construction kit.
"The handling and characterisation of these objects has become more and more important in materials science and nanotechnology," said nano-researcher Volkmar Eichhorn of the University of Oldenburg and its associated institute, OFFIS. "They have a huge application potential in various products."
The trouble is that nanotubes are too thin to see with a normal optical microscope. In addition, at this scale the intermolecular forces between objects are stronger than gravity, so once a nanotube has been picked up it will stick to the jaws of the gripper and cannot easily be dropped into position. The NanoHand team has had to develop novel pick-and-place techniques to get around this problem.
The robots, about two centimetres in size, work inside a scanning electron microscope, allowing an observer to follow their activities. Each has a microgripper that can make precise and delicate movements, using an electrothermal principle to open and close its tweezer-like jaws.
"The jaws open to about two micrometres and can pick up objects less than 100 nanometres in size. “[It is] really able to grip micro or even nano objects," Eichhorn said. "We have handled objects down to tens of nanometres.
"World-wide, we are the first project that has really realised the automated microgripper-based pick-and-place experiments," he added. "The new thing is the high accuracy and the small scale of the objects – in the range of tens or hundreds of nanometres – and the excellent control and software architecture being built around this whole set-up facilitating a high degree of automation."
Other groups are working on methods of handling nanotubes, especially in the USA, Japan and China, but the NanoHand system of microrobots and microgrippers is proving effective and reliable, claimed Eichhorn. "It’s very promising for nanotechnology applications," he said.
The first product built using NanoHand technology is already on the market - a scanning electron microscope with a carbon nanotube added to its tip to give it much improved resolution.
Now the project's industrial partners, who include STMicroelectronics, are looking at other potential applications, such as using carbon nanotubes for the interconnects within silicon chips. Because of their high electrical conductivity, carbon nanotubes dissipate less heat than copper and allow circuits to be packed more densely.
NanoHand received funding from the ICT strand of the EU’s Sixth Framework Programme for research. The project participants include British, Czech, Danish, German, Italian and Swiss organisations.