Probe-Tip Induced Damage in Compliant Substrates

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
Michael Chandross ◽  
Christian D. Lorenz ◽  
Mark J. Stevens ◽  
Gary S. Grest
Keyword(s):  
Data Storage ◽  
Realistic Model ◽  
Experimental Measurements ◽  
Material Transfer ◽  
Force Microscopy ◽  
Compliant Substrates ◽  
Atomic Force ◽  
Low Load ◽  
Afm Tips ◽  
Dynamics Simulations

Nanofabrication using arrays of modified atomic force microscopy (AFM) tips can drastically reduce feature sizes and increase data storage densities. Additionally, AFM experiments are valuable tools for characterizing the tribological properties of surfaces. In order to maximize the potential of nanofabrication techniques, it is necessary to understand fully the interactions between AFM tips and substrates, particularly when the latter is compliant and more damage-prone. To address this issue, we have carried out extensive molecular dynamics simulations of the nanotribological properties of self-assembled alkylsilane monolayers (SAMs) on amorphous silica with a realistic model of an AFM tip. Our simulations demonstrate that for fully physisorbed SAMs, even low load contacts can damage the SAM and cause material transfer to the probe tip. This effect, which is commonly ignored, can have a strong effect on the interpretation of experimental measurements. Partial chemisorption of the SAM lowers, but does not remove the possibility of damage.

scholarly journals Scale-Dependent Friction-Coverage Relations and Non-Local Dissipation in Surfactant Monolayers

2020 ◽  
Author(s):  
Hongyu Gao ◽  
James Ewen ◽  
Remco Hartkamp ◽  
Martin H. Müser ◽  
Daniele Dini
Keyword(s):  
Surface Coverage ◽  
Leading Edge ◽  
Thermal Dissipation ◽  
Nonequilibrium Molecular Dynamics ◽  
Kinetic Friction ◽  
Surfactant Monolayers ◽  
Force Microscopy ◽  
Sliding Surfaces ◽  
Atomic Force ◽  
Afm Tips

<div>Surfactant molecules, known as organic friction modifiers (OFMs), are added to lubricants to reduce friction and wear between sliding surfaces. In macroscale experiments, friction generally decreases as the coverage of OFM molecules on the sliding surfaces increases. However, recent nanoscale experiments with sharp atomic force microscopy (AFM) tips have shown increasing friction. To elucidate the origin of these opposite trends, we use nonequilibrium molecular dynamics (NEMD) simulations and study kinetic friction between OFM monolayers and an indenting nanoscale asperity. For this purpose, we study various coverages of stearamide OFMs on iron oxide surfaces and silica AFM tips with different radii of curvature. For our small tip radii, the friction coefficient and indentation depth both have a non-monotonic dependence on OFM surface coverage, with maxima occurring at intermediate coverage. This suggests that friction is dominated by plowing. We rationalise the non-monotonic relations through a competition of two effects (confinement and packing density) that varying the surface coverage has on the effective stiffness of the OFM monolayers. We also show that kinetic friction is not very sensitive to the sliding velocity in the range studied, indicating that it originates from instabilities. Indeed, while friction predominately originates from the plowing action of the monolayers by the leading edge of the tip, thermal dissipation is mostly localised in molecules towards the trailing edge of the tip.</div>

scholarly journals Planar Boronic Graphene and Nitrogenized Graphene Heterostructure for Protein Stretch and Confinement

Biomolecules ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1756
Author(s):  
Xuchang Su ◽  
Zhi He ◽  
Lijun Meng ◽  
Hong Liang ◽  
Ruhong Zhou
Keyword(s):  
Single Molecule ◽  
Intrinsically Disordered Proteins ◽  
Electron Tunneling ◽  
Amyloid Β ◽  
Protein Sequencing ◽  
Disordered Proteins ◽  
Force Microscopy ◽  
Intrinsically Disordered ◽  
Atomic Force ◽  
Dynamics Simulations

Single-molecule techniques such as electron tunneling and atomic force microscopy have attracted growing interests in protein sequencing. For these methods, it is critical to refine and stabilize the protein sample to a “suitable mode” before applying a high-fidelity measurement. Here, we show that a planar heterostructure comprising boronic graphene (BC3) and nitrogenized graphene (C3N) sandwiched stripe (BC3/C3N/BC3) is capable of the effective stretching and confinement of three types of intrinsically disordered proteins (IDPs), including amyloid-β (1–42), polyglutamine (Q42), and α-Synuclein (61–95). Our molecular dynamics simulations demonstrate that the protein molecules interact more strongly with the C3N stripe than the BC3 one, which leads to their capture, elongation, and confinement along the center C3N stripe of the heterostructure. The conformational fluctuations of IDPs are substantially reduced after being stretched. This design may serve as a platform for single-molecule protein analysis with reduced thermal noise.

scholarly journals Modeling of DNA binding to the condensin hinge domain using molecular dynamics simulations guided by atomic force microscopy

2021 ◽  
Author(s):  
Hiroki Koide ◽  
Noriyuki Kodera ◽  
Shveta Bisht ◽  
Shoji Takada ◽  
Tsuyoshi Terakawa
Keyword(s):  
Molecular Dynamics ◽  
Atomic Force Microscopy ◽  
Molecular Dynamics Simulations ◽  
Coarse Grained ◽  
Force Microscopy ◽  
Atomic Force ◽  
Dna Loop ◽  
Dynamics Simulations ◽  
Dsdna Binding ◽  
Hinge Domain

The condensin protein complex compacts chromatin during mitosis using its DNA-loop extrusion activity. Previous studies proposed scrunching and loop-capture models as molecular mechanisms for the loop extrusion process, both of which assume the binding of double-strand (ds) DNA to the so-called hinge domain formed at the interface of the condensin subunits Smc2 and Smc4. However, how the hinge domain contacts dsDNA has remained unknown, potentially due to its conformational plasticity. Here, we conducted atomic force microscopy imaging of the budding yeast condensin holo-complex and used this data as basis for coarse-grained molecular dynamics simulations to model the hinge structure in a transient open conformation. We then simulated the dsDNA binding to open and closed hinge conformations, predicting that dsDNA binds to the outside surface when closed and to the outside and inside surfaces when open. Our simulations also suggested that the hinge can close around dsDNA bound to the inside surface. The conformational change of the hinge domain might be essential for the dsDNA binding regulation and play important roles in condensin-mediated DNA-loop extrusion.

scholarly journals Tip-Based Nanomachining on Thin Films: A Mini Review

2021 ◽  
Author(s):  
Shunyu Chang ◽  
Yanquan Geng ◽  
Yongda Yan
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Data Storage ◽  
Three Dimensional ◽  
Maintenance Cost ◽  
Two Dimensional ◽  
Force Microscopy ◽  
Atomic Force ◽  
Current State ◽  
Two Dimensional Materials

AbstractAs one of the most widely used nanofabrication methods, the atomic force microscopy (AFM) tip-based nanomachining technique offers important advantages, including nanoscale manipulation accuracy, low maintenance cost, and flexible experimental operation. This technique has been applied to one-, two-, and even three-dimensional nanomachining patterns on thin films made of polymers, metals, and two-dimensional materials. These structures are widely used in the fields of nanooptics, nanoelectronics, data storage, super lubrication, and so forth. Moreover, they are believed to have a wide application in other fields, and their possible industrialization may be realized in the future. In this work, the current state of the research into the use of the AFM tip-based nanomachining method in thin-film machining is presented. First, the state of the structures machined on thin films is reviewed according to the type of thin-film materials (i.e., polymers, metals, and two-dimensional materials). Second, the related applications of tip-based nanomachining to film machining are presented. Finally, the current situation of this area and its potential development direction are discussed. This review is expected to enrich the understanding of the research status of the use of the tip-based nanomachining method in thin-film machining and ultimately broaden its application.

scholarly journals Towards an Understanding of Crystallization by Attachment

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 463
Author(s):  
Haihua Pan ◽  
Ruikang Tang
Keyword(s):  
Capillary Condensation ◽  
Force Measurements ◽  
Force Microscopy ◽  
Physical Conditions ◽  
Driving Mechanisms ◽  
Atomic Force ◽  
Wide Range ◽  
Dynamics Simulations ◽  
Hydration Layers

Crystallization via particle attachment was used in a unified model for both classical and non-classical crystallization pathways, which have been widely observed in biomimetic mineralization and geological fields. However, much remains unknown about the detailed processes and driving mechanisms for the attachment. Here, we take calcite crystal as a model mineral to investigate the detailed attachment process using in situ Atomic Force Microscopy (AFM) force measurements and molecular dynamics simulations. The results show that hydration layers hinder the attachment; however, in supersaturated solutions, ionic bridges are formed between crystal gaps as a result of capillary condensation, which might enhance the aggregation of calcite crystals. These findings provide a more detailed understanding of the crystal attachment, which is of vital importance for a better understanding of mineral formation under biological and geological environments with a wide range of chemical and physical conditions.

scholarly journals Heated-Tip AFM: Applications in Nanocomposite Polymer Membranes and Energetic Materials

2007 ◽  
Vol 15 (1) ◽  
pp. 20-25
Author(s):  
Jason P. Killgore ◽  
William King ◽  
Kevin Kjoller ◽  
René M. Overney
Keyword(s):  
Data Storage ◽  
Energetic Materials ◽  
Measurement Capability ◽  
Force Microscopy ◽  
Atomic Force ◽  
Nanocomposite Polymer ◽  
Wide Range ◽  
Measurement And Analysis ◽  
Nanoscale Topography ◽  
Temperature Controlled

Atomic Force Microscopy (AFM) is a key technique for the measurement and analysis of samples when nanoscale topography is of interest. It offers a number of complementary probing modes that extend an AFM's measurement capability to a wide range of material and transport properties of surfaces, including hardness, friction, conductivity and adhesion among others. Sample temperature controlled AFM extends the study of surface morphology and properties to include changes in the material phases.Recently, silicon microfabricated AFM cantilevers that have integrated heaters, as shown in figure 1, have become commercially available. These cantilevers were initially developed for probe based data storage by researchers at IBM Zurich, Figure 1. With the availability of these cantilevers, AFM measurements can be performed where the tip is heated as opposed to the sample.

scholarly journals 3D-printed cellular tips for tuning fork atomic force microscopy in shear mode

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Liangdong Sun ◽  
Hongcheng Gu ◽  
Xiaojiang Liu ◽  
Haibin Ni ◽  
Qiwei Li ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Shear Mode ◽  
Unique Contribution ◽  
Force Microscopy ◽  
Atomic Force ◽  
Afm Tips ◽  
3D Printed ◽  
Architectured Material ◽  
Energy Absorbing ◽  
Absorption Field

AbstractConventional atomic force microscopy (AFM) tips have remained largely unchanged in nanomachining processes, constituent materials, and microstructural constructions for decades, which limits the measurement performance based on force-sensing feedbacks. In order to save the scanning images from distortions due to excessive mechanical interactions in the intermittent shear-mode contact between scanning tips and sample, we propose the application of controlled microstructural architectured material to construct AFM tips by exploiting material-related energy-absorbing behavior in response to the tip–sample impact, leading to visual promotions of imaging quality. Evidenced by numerical analysis of compressive responses and practical scanning tests on various samples, the essential scanning functionality and the unique contribution of the cellular buffer layer to imaging optimization are strongly proved. This approach opens new avenues towards the specific applications of cellular solids in the energy-absorption field and sheds light on novel AFM studies based on 3D-printed tips possessing exotic properties.

Nanoscale organic data storage using atomic force microscopy

2003 ◽  
Author(s):  
B. McCarthy ◽  
K. Yamnitskiy ◽  
Y. Zhao ◽  
G.E. Jabbour ◽  
D. Sarid
Keyword(s):  
Atomic Force Microscopy ◽  
Data Storage ◽  
Force Microscopy ◽  
Atomic Force

Kinetics of Crystal Nucleation and Growth in Thin Films of Amorphous Te Alloys measured by Atomic Force Microscopy

2003 ◽  
Vol 803 ◽  
Author(s):  
J. Kalb ◽  
F. Spaepen ◽  
M. Wuttig
Keyword(s):  
Thin Films ◽  
Atomic Force Microscopy ◽  
Crystal Growth ◽  
Data Storage ◽  
Optical Data Storage ◽  
Crystal Nucleation ◽  
Ex Situ ◽  
Optical Data ◽  
Force Microscopy ◽  
Atomic Force

ABSTRACTBoth the crystal nucleation rate and the crystal growth velocity of sputtered amorphous Ag0.055In0.065Sb0.59Te0.29 and Ge4Sb1Te5 thin films used for optical data storage were determined as a function of temperature. Crystals were directly observed using ex-situ atomic force microscopy, and their change in size after each anneal was measured. Between 140°C and 185°C, these materials exhibited similar crystal growth characteristics, but differed in their crystal nucleation characteristics. These observations provide an explanation for the different re-crystallization mechanisms observed upon laser-induced crystallization of amorphous marks.

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