Keywords: Atomic Force Microscopy AFM、 Nanomechanics, single-molecule manipulation, force spectrum analysis

Atomic force microscopy (AFM) measures nanoscale morphology and mechanical properties through the interaction force between microcantilever probes and sample surfaces. Its core advantages include high resolution, non-destructive, and multimodal imaging, which are widely used in materials science, biophysics, and nanotechnology.

1、 The core principle and imaging mode of AFM

AFM detects the bending of microcantilever through laser reflection, indirectly measuring the force between the probe and the sample. The contact mode is suitable for hard samples, while the tapping mode reduces damage to soft samples. For example, in DNA imaging, the tapping mode can maintain the natural conformation of the molecule with a resolution of 0.1 nanometers.

2、 Nanomechanical testing: from elastic modulus to adhesion force

AFM can quantitatively measure the mechanical properties of samples. For example, in polymer materials, the force distance curve can analyze the elastic modulus and adhesion force; In biofilm research, AFM can measure the mechanical stability of cell membranes and reveal the effects of disease-related mutations.

3、 Single molecule manipulation and force spectrum analysis

AFM combined with force spectrum technology can achieve the study of single molecule stretching and folding. For example, by stretching DNA molecules, their persistence length and elasticity coefficient can be determined; In protein research, force spectra can reveal the mechanical mechanisms of conformational transitions.

4、 Technological bottlenecks and future directions

The current challenges include probe wear, environmental noise, and data analysis complexity. Future trends include:

High speed AFM: The scanning speed is increased to the millisecond level to observe dynamic biological processes.

Multi physics field coupling: Combining electric, magnetic, and temperature fields to study molecular behavior under external fields.

Integrated system: Combining AFM with optical microscopes and mass spectrometers to achieve multidimensional characterization.