Research On Corona Discharge Based On AFM Probe

Information acquisition of physical and chemical characteristics under the micro and nano scale would be very important for exploring the secret in the micro and nano world. After comparison of some in-situ and quasi-synchronous analysis methods of micro and nano structure material, We reported a scheme which is based on AFM-FAIMS: When interesting patterns were observed during AFM scan, a relatively high voltage was applied to the AFM probe to induce corona discharge at the point of interest. Analytes were ionized by this desorption-ionization method to charged molecules or atoms, and they were extracted to FAIMS chip by radial electric field exerted by a ring electrode at the AFM-FAIMS interface. Then FAIMS would be used to detect the analytes and validate the proposed method of in-situ physical and chemical characterization of micro and nano structure material.Some preliminary research on AFM probe based corona discharge for desorption ionization in AFM-FAIMS was put forward in this paper. The characteristics of corona discharge was introduced. The requirement , onset voltage and the onset electric intensity was also discussed. Then We did an tip-plane corona discharge experiment (d=3mm), we found that the result was in accordance with the theory. An simple introduction was given to AFM probe, FEA and ANSYS software. Through finite element analysis, research was done on the mechanical and electrical character of the AFM probe. Electrical analysis showed that the field intensity around the AFM probe tip could achieve 0.32v/um-62.4v/um when the gap distance was 100um and the applied voltage was 1000v, validating the feasibility of the sampling device. The relationship between discharge current I and applied voltage V was studied through corona discharge experiment. These works laid a foundation for developing the corona discharge non-contact sampling device based on AFM probe. Then we used MEMS technology to fabricate Si tips array for corona discharge research. A novel structure of AFM probe was introduced, and research was done on the electrical characteristic of the novel probe through ANSYS software.