Georgia Institute of TechnologypicoForce Laboratory
Zinc Oxide nanobeltProfile: Elisa RiedoNanofriction plot


Fundamental research and technological applications involve exceedingly small mechanically moving components. This requires an improved understanding of mechanical, and tribological properties appearing at the relevant length scales. In biology, understanding the mechanical behavior of nanotubulus such as acquaporine and DNA strands is crucial to comprehend the structural dynamics of cellular processes.
Our goal is to measure quantitatively, the Young and shear moduli of nanotubes (C, SiC, Si, etc), and biological tubulus by means of a new powerful method: modulated nanoindenting. With this method, we will also investigate the mechanical properties of new and interesting nano-objects, namely oxides nanosprings, nanobelts and nanorings, which can have future applications in NEMS (nano-electrical-mechanical systems), nano-electronic devices and nano-sensors.
Modulated nanoindenting is based on the atomic force microscopy (AFM) which permits to image and manipulate nano-objects and at the same time to measure normal and lateral forces with pico-Newton resolution.
We are able to acquire a map of the topography (with nanoscopic resolution) and at the same time a map of the transversal Young modulus and shear moduli of the nano-object. This gives access to the mechanical properties of each point of the nano-object, which is particularly interesting for inhomogeneous samples such as DNA.
Furthermore, during these experiments we can measure the area of contact along with friction and adhesion forces between the AFM tip and the object. Friction forces are usually a convolution of contact area and shear strength t . This prevents to relate the friction behavior to the structural properties of the materials. Our measurements, giving access to the area of contact, will permit to determine the nanoscopic value of t, which characterizes the intrinsic friction properties of a material.
This opens up new possibilities to understand the atomic processes occurring at the tip-sample interface when they are in contact, separated or moved with respect to one another. These processes are central for fundamental and technological problems including nanoelasticity, adhesion, friction, wear and lubrication.

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