Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 3 of 3
Full-Text Articles in Engineering
Quantitative Assessment Of Sample Stiffness And Sliding Friction From Force Curves In Atomic Force Microscopy, Nancy Burnham, Jon Pratt, Gordon Shaw, Lee Kumanchik
Quantitative Assessment Of Sample Stiffness And Sliding Friction From Force Curves In Atomic Force Microscopy, Nancy Burnham, Jon Pratt, Gordon Shaw, Lee Kumanchik
Nancy A. Burnham
It has long been recognized that the angular deflection of an atomic force microscope(AFM) cantilever under “normal” loading conditions can be profoundly influenced by the friction between the tip and the surface. It is shown here that a remarkably quantifiable hysteresis occurs in the slope of loading curves whenever the normal flexural stiffness of the AFM cantilever is greater than that of the sample. This situation arises naturally in cantilever-on-cantilever calibration, but also when trying to measure the stiffness of nanomechanical devices or test structures, or when probing any type of surface or structure that is much more compliant along …
Optimal Roughness For Minimal Adhesion, Nancy Burnham, D-L Liu, J Martin
Optimal Roughness For Minimal Adhesion, Nancy Burnham, D-L Liu, J Martin
Nancy A. Burnham
Roughness has a significant affect on adhesion. The authors used a single-asperity model to describe a smooth tip in contact with a rough surface and predicted that an optimal size of asperity yields a minimum of adhesion. Experimentally, adhesive forces on silicon wafers with varying roughness were measured using atomic-force-microscopy cantilevers with varying tip radii. It was found that minima do exist, and for all tip radii, the adhesion falls significantly for roughness greater than 1–2nm and drops at higher roughness for larger tips. This work should help minimize stiction in microelectromechanical systems and progress the understanding of nanoscale-contact mechanics.
Precision And Accuracy Of Thermal Calibration Of Atomic Force Microscopy Cantilevers, Nancy Burnham, G Matei, E Thoreson, J Pratt, D Newell
Precision And Accuracy Of Thermal Calibration Of Atomic Force Microscopy Cantilevers, Nancy Burnham, G Matei, E Thoreson, J Pratt, D Newell
Nancy A. Burnham
To have confidence in force measurements made with atomic force microscopes(AFMs), the spring constant of the AFM cantilevers should be known with good precision and accuracy, a topic not yet thoroughly treated in the literature. In this study, we compared the stiffnesses of uncoated tipless uniform rectangular silicon cantilevers among thermal, loading, and geometric calibration methods; loading was done against an artifact from the National Institute of Standards and Technology (NIST). The artifact was calibrated at NIST using forces that were traceable to the International System of units. The precision and accuracy of the thermal method were found to be …