Rapid Probe Engagement and Withdrawal With Online Minimized Probe-Sample Interaction Force in Atomic Force Microscopy

2018 ◽  
Author(s):  
Jingren Wang ◽  
Qingze Zou
Keyword(s):  
Atomic Force Microscopy ◽  
Measurement Errors ◽  
High Speed ◽  
Interaction Force ◽  
Adhesive Force ◽  
Repulsive Force ◽  
Control Technique ◽  
Force Microscopy ◽  
Atomic Force ◽  
Highly Nonlinear

In this paper, the problem of rapid probe engagement and withdrawal in atomic force microscopy (AFM) is addressed. Probe engagement to and withdrawal from the sample, respectively, are fundamental steps in all AFM operations, ranging from imaging to nanomanipulation. However, due to the highly nonlinear force-distance relation and the rapid transition between the attractive and the repulsive force dominance, a quick “snap-in” of the probe and excessively large repulsive force during the engagement, and a large adhesive force during the withdrawal are induced, resulting in sample deformation and damage, and measurement errors. Such adverse effects become more severe when the engagement and withdrawal is at high speeds, and the sample is soft (such as the live biological samples). Rapid engagement and withdrawal is needed to achieve high-speed AFM operations, particularly, to capture and interrogate dynamic evolutions of the sample. We propose a learning-based online optimization technique to minimize the probe-sample interaction force in high-speed engagement and withdrawal. Specifically, the desired force and probe position trajectory profile is online designed by using the optimal trajectory design technique, and tracked by using iterative learning control technique. Then the designed force-trajectory profile is online optimized to minimize the engagement force and the adhesive force. The proposed rapid engagement and withdrawal technique is illustrated through experimental implementation on a Polydimethylsiloxane (PDMS) sample.

scholarly journals High-speed dynamic-mode atomic force microscopy imaging of polymers: an adaptive multiloop-mode approach

2017 ◽  
Vol 8 ◽  
pp. 1563-1570 ◽  
Author(s):  
Juan Ren ◽  
Qingze Zou
Keyword(s):  
Atomic Force Microscopy ◽  
High Speed ◽  
Interaction Force ◽  
Dynamic Mode ◽  
Microscopy Imaging ◽  
Force Microscopy ◽  
Atomic Force ◽  
Atomic Force Microscopy Imaging ◽  
Mode Tm ◽  
Mode Atomic Force Microscopy

Adaptive multiloop-mode (AMLM) imaging to substantially increase (over an order of magnitude) the speed of tapping-mode (TM) imaging is tested and evaluated through imaging three largely different heterogeneous polymer samples in experiments. It has been demonstrated that AMLM imaging, through the combination of a suite of advanced control techniques, is promising to achieve high-speed dynamic-mode atomic force microscopy imaging. The performance, usability, and robustness of the AMLM in various imaging applications, however, is yet to be assessed. In this work, three benchmark polymer samples, including a PS–LDPE sample, an SBS sample, and a Celgard sample, differing in feature size and stiffness of two orders of magnitude, are imaged using the AMLM technique at high-speeds of 25 Hz and 20 Hz, respectively. The comparison of the images obtained to those obtained by using TM imaging at scan rates of 1 Hz and 2 Hz showed that the quality of the 25 Hz and 20 Hz AMLM imaging is at the same level of that of the 1 Hz TM imaging, while the tip–sample interaction force is substantially smaller than that of the 2 Hz TM imaging.

scholarly journals Error Analysis of the Combined-Scan High-Speed Atomic Force Microscopy

Sensors ◽  
2021 ◽  
Vol 21 (18) ◽  
pp. 6139
Author(s):  
Lu Liu ◽  
Ming Kong ◽  
Sen Wu ◽  
Xinke Xu ◽  
Daodang Wang
Keyword(s):  
Atomic Force Microscopy ◽  
Measurement Errors ◽  
High Speed ◽  
Large Error ◽  
Experimental Results ◽  
Force Microscopy ◽  
Atomic Force ◽  
Four Quadrant ◽  
Design Ideas ◽  
Response Errors

A combined tip-sample scanning architecture can improve the imaging speed of atomic force microscopy (AFM). However, the nonorthogonality between the three scanners and the nonideal response of each scanner cause measurement errors. In this article, the authors systematically analyze the influence of the installation and response errors of the combined scanning architecture. The experimental results show that when the probe in the homemade high-speed AFM moves with the Z-scanner, the spot position on the four-quadrant detector changes, thus introducing measurement error. Comparing the experimental results with the numerical and theoretical results shows that the undesired motion of the Z-scanner introduces a large error. The authors believe that this significant error occurs because the piezoelectric actuator not only stretches along the polarization direction but also swings under nonuniform multifield coupling. This article proposes a direction for further optimizing the instrument and provides design ideas for similar high-speed atomic force microscopes.

scholarly journals Histone variant H2A.B-H2B dimers are spontaneously exchanged with canonical H2A-H2B in the nucleosome

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Rina Hirano ◽  
Yasuhiro Arimura ◽  
Tomoya Kujirai ◽  
Mikihiro Shibata ◽  
Aya Okuda ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Dna Repair ◽  
High Speed ◽  
Histone Chaperones ◽  
Histone H2a ◽  
Force Microscopy ◽  
Atomic Force ◽  
Open Conformation ◽  
Replication Sites ◽  
Histone Exchange

AbstractH2A.B is an evolutionarily distant histone H2A variant that accumulates on DNA repair sites, DNA replication sites, and actively transcribing regions in genomes. In cells, H2A.B exchanges rapidly in chromatin, but the mechanism has remained enigmatic. In the present study, we found that the H2A.B-H2B dimer incorporated within the nucleosome exchanges with the canonical H2A-H2B dimer without assistance from additional factors, such as histone chaperones and nucleosome remodelers. High-speed atomic force microscopy revealed that the H2A.B nucleosome, but not the canonical H2A nucleosome, transiently forms an intermediate “open conformation”, in which two H2A.B-H2B dimers may be detached from the H3-H4 tetramer and bind to the DNA regions near the entry/exit sites. Mutational analyses revealed that the H2A.B C-terminal region is responsible for the adoption of the open conformation and the H2A.B-H2B exchange in the nucleosome. These findings provide mechanistic insights into the histone exchange of the H2A.B nucleosome.

High-Speed Atomic Force Microscopy for Studying the Dynamic Behavior of Protein Molecules at Work

2006 ◽  
Vol 45 (3B) ◽  
pp. 1897-1903 ◽  
Author(s):  
Toshio Ando ◽  
Takayuki Uchihashi ◽  
Noriyuki Kodera ◽  
Atsushi Miyagi ◽  
Ryo Nakakita ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Dynamic Behavior ◽  
High Speed ◽  
Force Microscopy ◽  
Atomic Force ◽  
Protein Molecules
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