Nanotribology (atomic-scale friction)

Mechanical forces on small scales provide valuable and detailed information on the properties of the probed surface, such as wear, friction and adhesion. Understanding the role of dissipation energy and surface potential in frictional mechanisms is essential for tribology, nanoscale fabrication, catalysis and so on. Through the interaction between the sharp Atomic Force Microscope (AFM) cantilever tip and the surface, various forces can be measured during the scanning experiment, and disclose information in the atomic-resolution.

Single molecule force spectroscopy

In recent years single molecule force spectroscopy techniques have evolved considerably, becoming an important measure in addition to traditional bulk methods. While ensemble bulk measurements study the averaged properties of a system, single molecule measurements illuminate the tails of these properties’ distributions. Atomic force microscopy (AFM), which has the ability to detect subtle details at sub-nanometer resolution, can hold a single protein for long periods of time, thus exploring a wide spectrum of forces ranging from a few to thousands of pico-Newtons. The single protein recorded force traces disclose its mechanistic features, such as reaction rates, diffusion coefficients, unfolding/refolding dynamics, free-energy landscapes available to perform work and conformational transition. We focus our interest on exploring proteins and polymers phase-transitions in the presence of co-solutes with the intention to provide new information about the physical-chemistry aspects of the specific ion phenomenon.

Nanomechanics

We employ nanoindentation and adhesion measurements using AFM to study the nano- and meso-scale mechanical properties of surfaces, and the contact interaction between materials. Capturing atomic-scale interactions is important for fundamental research and technological applications. These interactions are manifested through adhesion work, which can be evaluated by direct measurement of adhesion (pull-off) forces. Besides the knowledge on the adhesive interaction between surfaces, such measurements can provide information on the contact strength (Young modulus) (nanoindentation). 

We use these measurements to study the Au-MoS2 interaction, investiation of hydrogel's mechanical properties, and the relation of contact mechanics to resuspension phenomenon.