Objections have been raised against proposed nanotech systems composed of rigid mechanical parts because of the potential for friction to arise from van der Waals or Casimir forces between moving parts separated by only fractions of a nanometer. Now Swedish scientists have developed a computer program to calculate Casimir forces between various types of nanostructured materials, which may help to determine whether significant friction problems exist in specific designs. From “Calculating the Casimir force between nanoparticles” on nanotechweb.org, written by Belle Dumé (requires free registration):
A computer programme that measures the Casimir force between nanostructured particles has been invented by scientists in Sweden. The model might allow the Casimir force between such objects to be controlled, which will be useful for nanomechanical devices where the force is a source of friction.
The mysterious attraction between two neutral, conducting surfaces in a vacuum was first predicted in 1948 by Henrik Casimir and cannot be explained by classical physics. He said that two uncharged parallel metal plates would attract each other because there is a net pressure acting on the plates that pushes them together. This pressure comes from the vacuum itself, which is full of “virtual particles” that dart in and out of existence. The pressure between the plates is lower than that outside because the space here is confined and smaller than that outside.
Tiny though it is, the Casimir effect becomes significant at distances of microns or less and actually causes parts in nano- and micro-electromechanical systems (NEMS and MEMS) to stick together.
Researchers are now able to measure the Casimir force in experiments, which has led to speculation about how it could be exploited in technology. With the new computer method, developed by Bo Sernelius and Carlos Román-Velázquez of Linköping University, it is now possible to calculate the Casimir force between objects made of metamaterials comprising nanoparticles. These are also known as nanostructured materials.
