Keywords: scanning probe microscope SPM、AFM、STM、 nanomanipulation

Scanning probe microscopy (SPM) achieves nanoscale morphology and physical property measurement through the interaction force between the probe and the sample surface. Its core branches include atomic force microscopy (AFM) and scanning tunneling microscopy (STM), providing revolutionary tools for nanotechnology and materials science.

1、 STM: The Pioneer of Atomic Resolution

STM is based on the quantum tunneling effect and measures surface morphology through the tunneling current between the probe and the sample. Its resolution can reach 0.1 nanometers, achieving single atom manipulation for the first time. For example, IBM scientists used STM to arrange xenon atoms on the surface of nickel and spelled out the "IBM" logo, ushering in a new era of nanomanufacturing.

STM has a wide range of applications in surface science. For example, in catalyst research, STM can observe atomic restructuring on metal surfaces, revealing dynamic changes in reaction active sites.

2、 AFM: From Mechanical Measurement to Biological Imaging

AFM detects force signals through microcantilever probes and is suitable for insulators and biological samples. Its core modes include contact mode, tapping mode, and force spectrum analysis. For example, in DNA imaging, the tapping mode can maintain the natural conformation of the molecule with a resolution of 0.1 nanometers.

The force spectrum technique of 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、 Nano manipulation and molecular assembly

SPM combined with force feedback technology can achieve the movement and assembly of single molecules. For example, carbon nanotubes can be captured and precisely placed on a substrate using AFM probes to construct nanoelectronic devices; In the field of biology, SPM can manipulate DNA molecules and study their mechanical mechanisms of folding and unfolding.

4、 Technological bottlenecks and future directions

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

High speed SPM: 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 SPM with optical microscopes and mass spectrometers to achieve multidimensional characterization.