Research On Key Technologies Of High-speed Multiparametric Atomic Force Microscope Imaging

Atomic force microscopy(AFM)multi-parameter measurement technology uses the tip of a AFM probe to apply microindentation to the sample,combined with the contact mechanics model to obtain various nanomechanical properties such as sample stiffness,Young's modulus,and surface adhesion.Because of their good environmental adaptability and high spatial resolution,multi-parametric atomic force microscopes are widely used to characterize mechanical parameters in materials,cells,and biomolecules.The requirements for the measurement of time-varying characteristic parameters of samples such as living cells and phase change materials place higher demands on the dynamic measurement capabilities of traditional multi-parameter AFM.In this paper,with the aim of improving the imaging speed of multi-parameter AFM scanning,a torsional peak force modulation imaging method based on T-probe is proposed to solve the problem of high-speed data transmission and processing,and a feed-forward controller is established to effectively improve the scanner.Scanning speed.The main research contents of this article include:First,the dynamic model of the T-type probe is established,and the transient response of the probe cantilever to the tip-sample force is analyzed,which shows that the first-order torsion has a higher response speed than the first-order deflection.Based on this,a torsion peak force modulation method of T-shaped probe is proposed.This method works at the first-order flexural resonance frequency and has a higher measurement speed than the traditional non-resonant flexural peak force modulation technique.Then,in response to the demand for higher measurement data processing speed in high-speed imaging mode,a noise reduction fast peak force extraction method based on FIR filter and window function was proposed,and a compression transmission scheme for torsional measurement signal was established using CIC filter.Reduce the time consumption of data processing and transmission and the occupation of the underlying logic resources.A high-speed imaging data processing system based on FPGA is constructed,which provides hardware support for AFM's high-speed multi-parameter scanning.Finally,the combined hysteresis-vibration model of the scanner is established,the parameter identification of the sub-model is completed,and the experiment verifies the correctness of the combined model.Based on the proposed combined model,a data-driven feedforward injection controller is designed,which includes a deconvolution vibration compensator with full-frequency accurate fitting capability and a hysteresis compensation PID solver that can adapt to different bias voltages.On the premise of the accuracy of the scanner movement,the movement speed of the scanner is increased.In this paper,the technology of contact force measurement,data processing and scanner motion control of high-speed multi-parameter atomic force microscope is studied,which provides an effective solution for improving the imaging speed of multi-parameter atomic force microscope.The study of characterization is of great significance,and has important application value for the characterization of the dynamic characteristics of biological cells and molecules and the iterative development of new materials.