From Molecules to Cells: Imaging Soft Samples with the Atomic Force Microscope

TLDR

The atomic force microscope, invented a few years ago, is now a widely used near‑field microscope routinely imaging hard surfaces with atomic resolution, but soft samples remain challenging. The paper provides an overview of applying atomic force microscopy to organic samples, from thin ordered films at molecular resolution to living cells. The authors discuss fundamental image‑formation mechanisms and introduce novel imaging modes that exploit tip‑sample interactions for local micromechanical property measurements. Images of Langmuir‑Blodgett films demonstrating mapping of local viscoelasticity and friction coefficient are presented as examples.

Abstract

Since its invention a few years ago, the atomic force microscope has become one of the most widely used near-field microscopes. Surfaces of hard sample are imaged routinely with atomic resolution. Soft samples, however, remain challenging. An overview is presented on the application of atomic force microscopy to organic samples ranging from thin ordered films at molecular resolution to living cells. Fundamental mechanisms of the image formation are discussed, and novel imaging modes are introduced that exploit different aspects of the tip-sample interaction for local measurements of the micromechanical properties of the sample. As examples, images of Langmuir-Blodgett films, which map the local viscoelasticity as well as the friction coefficient, are presented.