Research Of The Rules Of The Microscopic Surface Interaction Forces Based On FBG Nanometer Measurement System

Studies have shown that when the scale of the micro-nano probe reaches the nanometer or micrometer level,the microscopic surface force between the probe and the measurement surface will affect the probe.Therefore,this article focuses on the effect of microscopic surface interaction forces on micrometer-sized probes.The microscopic surface forces affecting the probe mainly include capillary force,van der Waals force,electrostatic force,and etc.In this paper,the formation mechanism of the interaction force is analyzed theoretically,and conducts an experimental study on the influence of factors such as the size of the tip of the probe tip,environmental humidity,and surface roughness on the microscopic forces.In this paper,a set of microscopic force measurement system based on fiber Bragg grating(FBG)is developed,and an experimental system for measuring microscopic surface force is constructed.using FBG as the sensitive element and remolding fiber fusion splicer to manufacture probe tip ball heads with different ball diameter sizes on the tip of FBG sensors.At the same time,the improved matched grating wavelength demodulation method is used to complete the demodulation of the measurement signal,and then the signal is processed by the designed hardware circuit to offset,modulate,amplify,demodulate,and filter to improve the sensitivity and anti-interference ability of the system.The measurement signals are processed by Lab VIEW software and collected in the computer.Finally,cooperate with the optical micro-motion stage and PI nano-driving platform to complete the experimental study of microscopic surface force.Through experimental tests,the sensitivity and resolution of the FBG micro force measurement system were 6.22 m V / nm and 2.89 nm,respectively.In the microscopic surface interaction forces experiment,the measurement results of two probes with different ball head diameters were compared.It was found that the interaction forces had a greater influence on the probes with larger ball diameters.Comparison experiments with various materials and sample surfaces with different surface characteristics have shown that the effect on the metal surface is slightly greater than that on the non-metallic surface.In addition,it is also found that the force of the surface with different roughness is basically similar.In order to explore the characteristics of the interaction force in different media,two sets of interaction force data in air and liquid environment were experimentally studied,and it was found that the medium is also an important reason for affecting the micro force.Finally,an error analysis and traceability of the various error sources that the interaction force measurement system may produce during measurement is made.