Sandia National Laboratories: New 'inchworm' actuator allows study of friction at the microscale

3/25/2004
"ALBUQUERQUE, N.M. - Creating a tool small enough to measure friction on a microelectromechanical systems (MEMS) device is not an easy task. The tool has to be about the width of a human hair.
Yet, researchers at the at the National Nuclear Security Administration's Sandia National Laboratories have developed a new 'inchworm' actuator instrument that provides detailed information about friction at the microscale.
The main objective of the project was to study the validity of Amonton's Law at the microscale. This law, first stated 300 years ago, says friction force is proportional to normal force (normal means perpendicular to the surfaces). Although it remains a good description of friction today, there are interesting deviations from Amonton's Law, especially at low normal forces, where adhesion between the two surfaces is thought to contribute an extra force. Because of the large surface-to-volume ratio at the microscale, these adhesive forces could cause a strong deviation from Amonton's Law. "
There have been many recent articles on use of MEMs in surgery and in sensors so it is important to know about the effect of friction. There are many articles in Compendex when you search ({MICROELECTROMECHANICAL DEVICES}) WN CV) AND ({FRICTION} WN CV). It stands to reason that there would be more at play than Amonton's Law at that scale.