Introduction information
Biological atomic force microscope
It mainly consists of a micro-cantilever with a needle tip, a micro-cantilever motion detection device, a feedback loop for monitoring its motion, a piezoelectric ceramic scanning device for scanning samples and a computer-controlled image acquisition, display and processing system. The motion of micro-cantilever can be detected by electrical methods such as tunnel current detection or optical methods such as beam deflection and interference. When the needle tip is close enough to the sample and there is short-range repulsion, the surface atomic resolution image can be obtained by detecting the repulsion, and the resolution is generally in the nanometer level. AFM measurement has no special requirements for the sample, and no special treatment is needed for the sample. It can only measure solid surface, adsorption system and so on. In the atmospheric environment, information such as three-dimensional surface roughness is obtained.
merits and demerits
superiority
Images observed by atomic force microscope
Compared with scanning electron microscope, atomic force microscope has many advantages. Unlike the electron microscope, which can only provide two-dimensional images, AFM provides real three-dimensional surface images. At the same time, AFM does not need to carry out any special treatment on the sample, such as copper plating or carbon plating, which will cause irreversible damage to the sample. Thirdly, the electron microscope needs to work in high vacuum, and the atomic force microscope can work well under normal pressure and even in liquid environment. This can be used to study biological macromolecules and even living biological tissues.
disadvantaged
Compared with scanning electron microscope (SEM), AFM has some disadvantages, such as too small imaging range, slow speed and too much influence by probe. Atomic Force Microscope (AFM) is a new type of atomic-level high-resolution instrument invented after scanning tunneling microscope. It can detect the physical properties of various materials and samples in the nanometer range, including morphology, or directly manipulate them in the nanometer scale. It has been widely used in the fields of semiconductors, nano-functional materials, biology, chemical industry, food, medical research and research experiments of various nano-related disciplines in scientific research institutes, and has become a basic tool for nano-scientific research. Compared with scanning tunneling microscope, atomic force microscope has wider applicability because it can observe non-conductive samples. At present, the scanning force microscope widely used in scientific research and industry is based on atomic force microscope.
application area
With the development of science and technology, life science began to develop in the direction of quantitative science. Most experiments focus on the relationship between the structure and related functions of biological macromolecules, especially nucleic acids and protein. Because of the wide working range of AFM, it can directly image biomedical samples in natural state (air or liquid) with high resolution. Therefore, AFM has become one of the important tools to study biomedical samples and biomacromolecules. The application of atomic force microscope mainly includes three aspects: observing the surface morphology of biological cells; Observe and study the structure and other properties of biological macromolecules; Observation of intermolecular force spectrum curve.
Scanning tunneling microscope, also known as "scanning tunneling microscope" and "tunneling scanning microscope", is an instrument that uses the tunneling effect in quantum theory to detect the surface structure of substances. It was invented by Gerd G.Binnig and H. heinrich H.Rohrer in the Zurich laboratory of IBM in Zurich, Switzerland in 198 1, so the two inventors shared the 1986 Nobel Prize in Physics with Ernst ruska.
Scanning tunneling microscope (STM) is a scanning probe microscope tool, which allows scientists to observe and locate a single atom, and it has higher resolution than similar atomic force microscopes. In addition, scanning tunneling microscope (STM) can accurately manipulate atoms with probe tips at low temperature (4K), so it is not only an important measuring tool but also a processing tool in nanotechnology.
STM makes it possible for human beings to observe the arrangement of single atoms on the surface of matter and the physical and chemical properties related to the surface electronic behavior for the first time. It has great significance and broad application prospects in the research of surface science, material science, life science and other fields, and is recognized by the international scientific community as one of the top ten scientific and technological achievements in the world in the 1980s.
Specific application
scan
When STM is working, the probe will be close enough to the sample to generate a highly spatially limited electron beam. Therefore, in imaging work, STM has a very high spatial resolution and can be used for scientific observation.
Inspection and maintenance
In the process of surface machining, STM can image the surface topography in real time, and can be used to find the defects and damages of various structures on the surface, establish or cut off the connection lines through surface deposition and etching, so as to eliminate the defects and achieve the purpose of repair, and then STM can also be used to image and check the quality of the repair results.