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

Abstract

Increasing the imaging rate of atomic force microscopy (AFM) without impairing of the imaging quality is a challenging task, since the increase in the scanning speed leads to a number of artifacts related to the limited mechanical bandwidth of the AFM components. One of these artifacts is the loss of contact between the probe tip and the sample. We propose to apply an additional nonlinear force on the upper surface of a cantilever, which will help to keep the tip and surface in contact. In practice, this force can be produced by the precisely regulated airflow. Such an improvement affects the AFM system dynamics, which were evaluated using a mathematical model that is presented in this paper. The model defines the relationships between the additional nonlinear force, the pressure of the applied air stream, and the initial air gap between the upper surface of the cantilever and the end of the air duct. It was found that the nonlinear force created by the stream of compressed air (aerodynamic force) prevents the contact loss caused by the high scanning speed or the higher surface roughness, thus maintaining stable contact between the probe and the surface. This improvement allows us to effectively increase the scanning speed by at least 10 times using a soft (spring constant of 0.2 N/m) cantilever by applying the air pressure of 40 Pa. If a stiff cantilever (spring constant of 40 N/m) is used, the potential of vertical deviation improvement is twice is large. This method is suitable for use with different types of AFM sensors and it can be implemented practically without essential changes in AFM sensor design.

Simulations of Subnanometer Scale Image Contrast in Atomic Force Microscopy of Self-Assembled Monolayers in Water

“…The tip was connected to a virtual atom, mimicking the cantilever, through a harmonic spring with a stiffness of 40 N/m. This spring constant was used to mimic a stiff cantilever used in existing subnanometer resolution imaging studies, 40 although a subset of the simulations were also run with a spring constant of 4 N/m ( section S6 ). A relaxation step that took 1 ns was used to ensure that the system reached 300 K. Once the system was relaxed, the virtual atom was oscillated in the z direction at a frequency of 91 GHz and a set driving amplitude, causing the tip to oscillate.…”

Analysis of a-Si:H Solar Cell Efficiency Based on Active Layer Composition

“…Untuk mengukur ketebalan dan morfologi sel surya a-Si:H menggunakan Atomic Force Microscopy (AFM), yang mengkarakterisasi bahan menggunakan gaya atom tip-substrat. AFM terdiri dari beberapa perangkat seperti nozel, kantilever, sensor piezoelektrik dan detektor cahaya (Dzedzickis et al, 2018). Pengukuran atau scan diambil dari batas antara coating dan substrat.…”

Nanomaterials for Biomedical Applications: Production, Characterisations, Recent Trends and Difficulties

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