Atomic force microscopy (AFM) has been recognized since the mid-eighties as an excellent technique to image a wide range of samples in their near-natural environment. Although the primary function of AFM is to generate three-dimensional (3D) profiles of the scanned surface, much more information can be delivered via this technique. In 1993, TappingMode was developed, which prevents tip and sample damage due to friction and shear forces and allows qualitative mechanical property mapping through phase imaging. About the same time, force spectroscopy and force volume (FV) were developed to study tip-sample forces at a point or over an area, respectively. To date, force spectroscopy and FV are the most commonly used AFM modes for measuring nanometer-scale mechanical forces in a quantitative manner. Unfortunately, force spectroscopy and FV suffer from slow acquisition speed and a lack of automated tools; these operating characteristics limit their use because of the hundreds or thousands of curves that are required for good statistics.

Atomic force microscopy (AFM) is one of the most powerful and dynamic methods for performing nanoscale imaging and materials characterization, enabling scientists and researchers to attain atomic resolution and measure nano-mechanical material properties in-situ, all while requiring minimal sample preparation. In spite of these clear advantages, user adoption of AFM has been limited by the technique's slow imaging speed as compared to light microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). However, recent advances in AFM technology have increased AFM imaging speeds by over an order of magnitude, opening up a wide range of new applications while greatly improving the user experience.

Though atomic force microscopy (AFM) interrogates biological materials through mechanical interactions, achieving quantitative mechanical information such as modulus and adhesion at high resolution has been a challenging task. A technology for nanometer scale mechanical property mapping, peak force tapping (PFT), was developed to achieve high resolution imaging and quantitative mechanical measurements simultaneously. PFT controls instantaneous interaction force and record force spectroscopy at each pixel to calculate mechanical properties. A feedback loop maintains a constant peak force, a local maximum point in the force spectroscopy, at the level of Pico Newtons throughout the imaging process. Such high precision force controls enable application of ultra-sharp probe to image biological samples in vitro and achieve molecular resolution in protein membranes. More importantly a full suite of mechanical properties, modulus, adhesion, energy dissipation and deformation are mapped concurrent with topographic imaging. To calculate nanomechanical properties reliably cantilever spring constant and tip shape were calibrated systematically. A method to accurately determine cantilever spring constant, capable of wafer scale cantilever calibration, was developed and tested against traceable force methods. With the knowledge of tip shape, derived from morphological dilation method using a reference sample, mechanical properties measured at the nanometer scale was compared with bench mark materials ranging from 0.7 MPa to 70 GPa. The same method was also applied to OmpG membranes, Lambda DNA strings, as well as live cells. The limitation of the measurement accuracy in biology samples will be discussed.

We recently developed an integrated imaging platform that combines single molecule evanescent wave fluorescence imaging (and spectroscopy) with in situ scanning probe microscopy. The advantages, challenges, and potential represented by this coupled tool will be described in the context of the structure-function characteristics of nanostructured biomaterials and thin lipid films.

We recently developed an integrated imaging platform that combines single molecule evanescent wave fluorescence imaging (and spectroscopy) with in situ scanning probe microscopy. The advantages, challenges, and potential represented by this coupled tool will be described in the context of the structure-function characteristics of nanostructured biomaterials and thin lipid films.