Dec 13, 2012
Deformation of nano-asperities captured on video
Researchers in Japan have used a transmission electron microscope in combination with a microelectromechanical system (MEMS) to observe atomic point contact between two opposing silver tips in real time. By watching how nano-asperities deform during lateral displacement, the team hopes to answer some of the questions that still remain on the topic of friction at the nanoscale.
To perform the measurement, the team developed an electrostatically driven MEMS, which could be operated in a TEM specimen chamber to achieve precise sub-nm actuation. The design is highly stable because charging drift, which is the major cause of drift in atmospheric conditions, does not occur in high vacuum conditions and thermal drift can be highly suppressed because all of the mechanical components are made of silicon monolithically.
Once contact between the silver asperities is obtained, the scientists apply a lateral displacement with an average velocity of 10 nm/min and observe the deformation of the contact area. In the work, the researchers demonstrate that a stick–slip-like phenomenon is present even during the deformation of nanoscale contacts.
The group believes that its observations of how surfaces in nanocontact change with a lateral deformation may give new insights for understanding fundamental friction phenomena, at least at the atomic scale.
Full results can be found in the journal Nanotechnology.
About the author
Takaaki Sato PhD is a project researcher in the University of Tokyo, Japan. He is currently combining micro machining technologies with TEM observation to explore friction mechanisms at the atomic level.