Characterization of Hydrodynamics and Behavior of Viscoelasticity at the Nanoscale

Board Of Regents, Nshe, Obo University Of Nevada, Reno, Reno NV

Investigators

Abstract

The ability to measure physical properties of materials at very small scales is key to advancing scientific research and technological progress. Measurements that occur at the nanoscale, where the physical dimensions involved are on the order of one billionth of a meter, are of particular importance. The atomic force microscope (AFM) is one of the primary tools for making quantitative measurements of material properties at the nanoscale. However, there exist many physical phenomena at the nanoscale that prevent accurate quantitative measurements from being made, especially in liquid environments. This project aims to understand and fully characterize two such phenomena: fluid forces that arise at the nanoscale when the AFM is operated in liquid environments (hydrodynamics) and the underlying principles that govern the behavior of the material being interrogated (viscoelasticity). This project will enable quantitative measurements of material properties at the nanoscale in liquid environments on a variety of inorganic and biological materials. This will enable new and cutting-edge research in areas such as medicine, biology, and materials engineering. In addition, the project's educational plan will develop a hands-on, interactive, and portable learning platform that will expose K-12, undergraduate, and graduate students to AFM and the scientific principles used in its operation. The educational plan will engender further interest and retention in the STEM fields. The primary objective of this project is to understand the effect that complex sample viscoelasticity and hydrodynamic forces at the nanoscale have on the resonant behavior of measurement systems by developing mathematical and numerical models that capture and quantify these phenomena. These effects can be addressed through the lens of contact resonance (CR) spectroscopy AFM. The CR spectroscopy system is an ideal measurement platform to understand these phenomena because it is well understood in the absence of these effects and has the ability to interrogate both the hydrodynamic and viscoelastic parameter spaces of interest. The focus of this project is on accurately predicting the three-dimensional fluid-structure interactions present in CR spectroscopy systems, establishing material models for CR spectroscopy to account for biological and non-classical viscoelastic materials, and experimentally validating the fluid-structure interaction and viscoelastic models. The success of the project will enable accurate contact resonance based quantitative nanomechanical characterization of biological materials in liquid environments, which in turn will facilitate research in several key areas such as study of biomaterials and bio-polymers with applications to the medical community, study of nanomechanical structural changes in osteoarthritic bones, and study of dentin and tooth enamel.