Scientists fight friction down to the last atom
By KATHARINE OTT
kott@journalsentinel.com
Posted: July 23, 2006
In the field of nanotechnology, where devices are one-billionth the size of everyday objects, friction - the resistant force of two objects rubbing together - is preventing some of these minuscule devices from being reliable enough to enter the commercial market.
Two new studies in the journal Science may get scientists closer to working around the problem of friction.
"Nanotechnology is a vast and multidisciplinary area," said Robert Carpick, a physicist at UW-Madison , "and for certain technologies, friction needs to be overcome."
Researchers in an area called nanotribology study the problem of reducing friction in micro- and nano-scaled electronic devices such as computer chips, microphones and drug-releasing mechanisms. Tribology is the science and technology of friction, lubrication and wear.
The studies outline a new method for reducing friction in micro- and nano-scale devices. Both approaches are unique because they physically alter the existing system - the pair of surfaces involved - rather than adding a chemical to act as a lubricant.
In the first study, friction was reduced by applying a voltage to the system. One of the surfaces involved was made of silicon. When an electric charge is applied to silicon, the electrons become either excited or subdued, depending on whether the charge is positive or negative.
Friction creates heat, and electrons are involved in the transfer of heat. So by altering the electrons, scientists can increase or decrease the amount of friction, said Miguel Salmeron, physicist at Lawrence Berkeley National Lab and one of the authors of the paper.
The second study, by Swiss physicist Anisoara Socoliuc, applied mechanical vibrations to the system.
