Force to Be Reckoned With

Advances such as miniscule submarine-type machines that destroy cancer cells could be one result of work to harness the Casimir force, which was accurately measured just a decade ago.

A pioneering team from the University of Leicester is believed to be the only group in the UK that is carrying out Casimir force measurements of smooth and patterned surfaces and assessing the utility of the force for nanotechnology.

The research arises from the quantum fluctuations of vacuum -- part of quantum field theory -- which at present is the universal theory describing the behavior of all quantum particles. The Casimir force is a subtle consequence of the vacuum fluctuations, which can be directly measured using the tools of nanotechnology, specifically atomic force microscopes.

Results of the research may lead to frictionless bearings and may solve one of the fundamental problems in nanomachines. Chris Binns, a professor of nanoscience in the department of physics and astronomy, said his team hopes to be able to harness the Casimir force as a way to transmit force without contact in nanomachines -- machines with components approaching the size of molecules.

"Generally, nanomachines are science fiction, and so it is up to the imagination about what they could do; but one of the most talked-about potential uses is in medical applications where submarine-type machines might be used to identify cancer cells and destroy them," Binns said.

Normally in such machines, the Casimir force is a problem because at the small distances between components the force is quite strong and generates a fundamental "stickiness" to everything which is impossible to remove. Professor Binns’ research is trying to turn the problem on its head and to use the Casimir force as a way to transmit force without contact, e.g., patterning a surface to produce the lateral force in which one patterned surface can drag another one in the same direction.

The force was first accurately measured about 10 years ago, and nanoscientists are currently trying to find ways to modify and use it, for instance in lateral force.

“The research is at a fundamental level," Binns said, "so at this stage, we only hope to determine how the force varies between surfaces composed of different materials and how patterning the surface changes it. Also, we want to measure the magnitude of the lateral force between surfaces. One new area we are starting to look at, however, is to measure the force between a normal material and a metamaterial." A metamaterial is a surface with a designed nanoscale patterning that gives strange optical properties.

“There are indications that with the right sort of patterning it may be possible to reverse the force to produce repulsion," Binns added. "This would have huge technological repercussions and lead to, for example, frictionless bearings, as well as getting rid of the stickiness problem in nanomachines. This is exciting research because it is controversial. Not everybody believes that a repulsive force is possible.”

For more information, visit: www.le.ac.uk