Nanoscale Mechanical Properties – Measuring Techniques and Applications

Abstract

This chapter describes local measurements and applications of nanoscale mechanical properties. It includes detailed state of the art presentation and in-depth analysis of experimental techniques, results and interpretations. After a short introduction, the second part of the chapter explores the application of local mechanical spectroscopy using coupled atomic force microscopy and ultrasound. This technique allows us to rapidly map elasticity and anelastic properties. Semiquantitative measurements can be taken as a function of temperature at specific point in the sample. The results obtained on the nanoscale are similar to those from bulk measurements, with interpretable differences. The local elasticity and damping were measured during phase transitions of polymer samples and shape-memory alloys. The third part describes the “nano-Swiss cheese” method of measuring the elastic properties of nanosized tubular objects such as carbon nanotubes and microtubules. It is probably the only experiment in which the properties of single-wall nanotube ropes have been measured as a function of the rope diameter. We extended this idea to biological objects, microtubules, and successfully solved major experimental difficulties. We not only measured the temperature dependency of the microtubule modulus under pseudo-physiological conditions, but we also estimated the shear modulus using the same microtubule with several lengths of suspended segments. The fourth section describes the scanning nanoindentation technique as applied to human bone tissue. This instrument allows topography scans and indentation tests to be performed using an identical tip. The technique allows the indenter tip to be positioned on structures of interest with great precision during suface scans. For very inhomogeneous samples, such as bone tissue, this tool provides a way to detect local variations in mechanical properties. The indentation test allows us to study quantitative parameters like elastic modulus and hardness at the submicron level. Using this, local mechanical properties of compact and trabecular bone lamellae were tested under both dry and pseudo-physiological conditions. The chapter ends with a discussion of future prospects for the field and some conclusions.