Implementation of Different Gas Influence for Operation of Modified Atomic Force Microscope Sensor

Abstract

This paper presents modelling of various gas application to modified atomic force microscope sensor in order to change its existing dynamic characteristics. This paper represents part of continuous research, which is focused on improvement of scanning speed of atomic force microscope (AFM) sensor. Subject of our research is enhancement of dynamic characteristics of Atomic force microscope sensor. Natural frequency of AFM sensor is the main factor influencing max scanning speed of atomic force microscope. In case of working range of frequencies approaches to the resonant frequency of cantilever, scanning results becoming inaccurate and unreliable. Improvement of properties of atomic force sensor made by adding additional nonlinear aerodynamic force to the AFM sensor. This force would act as additional controllable stiffness element, which allows shift resonant frequency to higher side. In this paper is presented research of additional nonlinear force behavior using different gasses as well as compressed air. Research covers factor of humidity of compressed air. Our research performed using 3D atomic microscope cantilever model in SolidWorks flow simulation software. Results of simulation delivered as dependencies of additional stiffness in the AFM sensor in all modelled cases. Finally, results presented in graphical form and conclusions are drawn.

Modification of the AFM Sensor by a Precisely Regulated Air Stream to Increase Imaging Speed and Accuracy in the Contact Mode

“…The parameters of the aerodynamic force were determined from the theoretical 3D model of the microscope cantilever, as reported previously [ 17 ]. This model describes the dependencies among the air gap, the pressure of compressed air, and the resulting force on the cantilever.…”

“…This model describes the dependencies among the air gap, the pressure of compressed air, and the resulting force on the cantilever. The displacement of the cantilever at coordinate η 2 ( Figure 1 ) defined from results of finite element modelling (FEM) analysis [ 17 ] and approximated by polynomial in respect to relative gap and expressed in terms of our model, is: η 2 = −0.0007·(Δ 0 − η 1 ) 3 + 0.0033·(Δ 0 − η 1 ) 2 + 0.0063·(Δ 0 − η 1 ) + 0.0049 …”

“…For the introduction of the airflow with the microscope, it is enough to produce a cantilever holder with an installed micro air duct and a precise airflow control system. The effect of an applied aerodynamic force depends on: the initial gas pressure, the air duct diameter and shape, and the initial gap size between air duct and cantilever surface [ 16 , 17 ].…”

Modification of the AFM Sensor by the Precisely Regulated Air Stream to Increase the Imaging Speed and Accuracy

“…The parameters of the aerodynamic force were determined using our previous research results from the theoretical 3D model of the microscope cantilever [17]. This model provided the dependencies among the air gap, the pressure of compressed air and the resulting force on the cantilever.…”

“…For the introduction of the airflow to the microscope it is enough to produce a cantilever holder with an installed micro air duct and a precise airflow control system. In earlier research, it was found that the AFM cantilever is sensitive to air stream [12,17]. The effect of an applied aerodynamic force depends on: initial gas pressure, air duct diameter and shape, initial gap size between air duct and cantilever surface.…”