Designing nonlinear observer for topography estimation in trolling mode atomic force microscopy

2021 ◽  
pp. 107754632110381
Author(s):  
Mohammadreza Sajjadi ◽  
Mahmood Chahari ◽  
Hossein Nejat Pishkenari ◽  
Gholamreza Vossoughi
Keyword(s):  
System Dynamics ◽  
Surface Topography ◽  
High Speed ◽  
Scanning Speed ◽  
Sample Surface ◽  
Nonlinear Observer ◽  
Time Duration ◽  
Force Microscopy ◽  
The Stability ◽  
High Scanning Speed

In this study, a nonlinear observer for high-speed estimation of the sample surface topography in a small duration of the probe transient motion utilizing a 2DOF model of TR-AFM is proposed. Since the time duration to reach the steady-state periodic motion of the oscillating probe in conventional imaging methods is relatively high, the proposed nonlinear observer in this research is able to address this limitation and estimate the surface topography throughout transient oscillation of the microcantilever. With this aim, topography estimation process utilizing a Thau observer without any linearization of the system dynamics is designed and coupled with the system dynamics to achieve sample topography. The stability of the proposed observer coupled with controller is verified by the Lyapunov stability theorem for the first time, and hence, linearization of the model is not required. Simulation results demonstrate the feasibility of the presented approach to estimate different sample heights with high accuracy and a relatively high scanning speed. Additionally, the effects of measurement noise and horizontal nanoneedle tip displacement on the performance of proposed technique are investigated.

scholarly journals A Non-Destructive, Tuneable Method to Isolate Live Cells for High-Speed AFM Analysis

2021 ◽  
Vol 9 (4) ◽  
pp. 680
Author(s):  
Christopher T. Evans ◽  
Sara J. Baldock ◽  
John G. Hardy ◽  
Oliver Payton ◽  
Loren Picco ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
High Resolution ◽  
High Speed ◽  
Single Cells ◽  
Sample Surface ◽  
Live Cells ◽  
Contact Mode ◽  
Force Microscopy ◽  
Atomic Force ◽  
Afm Analysis

Suitable immobilisation of microorganisms and single cells is key for high-resolution topographical imaging and study of mechanical properties with atomic force microscopy (AFM) under physiologically relevant conditions. Sample preparation techniques must be able to withstand the forces exerted by the Z range-limited cantilever tip, and not negatively affect the sample surface for data acquisition. Here, we describe an inherently flexible methodology, utilising the high-resolution three-dimensional based printing technique of multiphoton polymerisation to rapidly generate bespoke arrays for cellular AFM analysis. As an example, we present data collected from live Emiliania huxleyi cells, unicellular microalgae, imaged by contact mode High-Speed Atomic Force Microscopy (HS-AFM), including one cell that was imaged continuously for over 90 min.

scholarly journals Microstructures and Wear Resistance of FeCoCrNi-Mo High Entropy Alloy/Diamond Composite Coatings by High Speed Laser Cladding

Coatings ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 300 ◽  
Author(s):  
Haijiang Wang ◽  
Wei Zhang ◽  
Yingbo Peng ◽  
Mingyang Zhang ◽  
Shuyu Liu ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Composite Coating ◽  
Laser Cladding ◽  
High Speed ◽  
Composite Coatings ◽  
Scanning Speed ◽  
High Entropy Alloy ◽  
Dilution Ratio ◽  
High Entropy ◽  
High Scanning Speed

FeCoCrNi-Mo high entropy alloy/diamond composite coatings were successfully prepared by high speed laser cladding. A high scanning speed was adopted (>30 mm/s), and the effects of laser power, scanning speed, and diamond content on the microstructure and wear resistance of the composite coating were studied. The processing parameters of laser cladding had significant influence on the dilution ratio, graphitization of diamond, and wear resistance of the composite coatings. When the laser cladding parameters were 3000 W of laser power and the high scanning speed of 50 mm/s, the composite coating exhibited a uniform microstructure, the lowest dilution ratio, and the best wear resistance. The wear resistance of the composite coating was enhanced with the addition of diamond, but microcracks also increased. When the amount of diamond was 15 wt.%, the best combination of microstructures and wear resistance was obtained.

scholarly journals Атомный состав и морфология тонких пленок ресвератрола на поверхности окисленного кремния и поликристаллического золота

2019 ◽  
Vol 61 (3) ◽  
pp. 598
Author(s):  
А.С. Комолов ◽  
Э.Ф. Лазнева ◽  
Н.Б. Герасимова ◽  
В.С. Соболев ◽  
Ю.А. Панина ◽  
...  
Keyword(s):  
Surface Area ◽  
Photoelectron Spectroscopy ◽  
Sample Surface ◽  
Total Surface Area ◽  
Contact Mode ◽  
Force Microscopy ◽  
Scanning Area ◽  
Before And After ◽  
The Stability ◽  
Substrate Surfaces

AbstractThe atomic composition of films of a polyphenol antioxidant, namely, resveratrol (RVL), with a thickness of up to 50 nm thermally deposited on an oxidized silicon surface is studied by the method of X-ray photoelectron spectroscopy (XPS). It is found that the surface area of pores in the RVL film is about 15% of the total surface area. The results of studying the stability of the RVL films when their surface is treated with Ar^+ ions of 3 keV under the electric current of 1 μA passing through the sample for 30 s are given. The treatment gives rise to an increase in the area of pores to 30–40%, while the ratio of the concentration of C atoms to the concentration of O atoms in the RVL film both before and after the treatment of the surface with ions does not correspond to the chemical formula of RVL molecules. Using the method of atomic force microscopy (AFM) in contact mode with a scanning area size of about 10 × 10 μm, RVL coatings deposited on the oxidized silicon and polycrystalline Au surfaces are studied. It is found that the RVL films produce grainy and porous coatings on the substrate surfaces. The typical size of grains in the sample surface plane is 150–300 nm, and the characteristic elevation reaches 30 nm.

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

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2694 ◽  
Author(s):  
Andrius Dzedzickis ◽  
Vytautas Bucinskas ◽  
Darius Viržonis ◽  
Nikolaj Sesok ◽  
Arturas Ulcinas ◽  
...  
Keyword(s):  
Aerodynamic Force ◽  
Scanning Speed ◽  
Spring Constant ◽  
Contact Mode ◽  
Force Microscopy ◽  
Atomic Force ◽  
Air Stream ◽  
Nonlinear Force ◽  
Loss Of Contact ◽  
High Scanning Speed

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.

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

2018 ◽  
Author(s):  
Andrius Dzedzickis ◽  
Vytautas Bucinskas ◽  
Darius Viržonis ◽  
Nikolaj Sesok ◽  
Arturas Ulcinas ◽  
...  
Keyword(s):  
Aerodynamic Force ◽  
Scanning Speed ◽  
Interaction Force ◽  
Spring Constant ◽  
Force Microscopy ◽  
Atomic Force ◽  
Air Stream ◽  
Nonlinear Force ◽  
High Scanning Speed ◽  
Speed And Accuracy

Increasing of the imaging rate of conventional atomic force microscopy (AFM) is almost impossible without impairing of the imaging quality, since the probe tip tends to lose contact with the sample. We propose to apply the 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 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 higher surface roughness, and at the same time has minimal influence on the interaction force, thus maintaining stable contact between the probe and the surface. This improvement allows 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 accuracy improvement reaches 92 times. This method is suitable for use with different types of AFM sensors and can be implemented practically without essential changes in AFM sensor design.

Development of a High-Speed Laser-Free Atomic Force Microscopy

2009 ◽  
Author(s):  
Saeid Bashash ◽  
Reza Saeidpourazar ◽  
Nader Jalili
Keyword(s):  
Atomic Force Microscopy ◽  
Surface Topography ◽  
Control Strategy ◽  
High Speed ◽  
Wheatstone Bridge ◽  
Robust Adaptive Control ◽  
Superior Performance ◽  
Force Microscopy ◽  
Atomic Force ◽  
Scanning Area

To reduce the cost and improve the speed of Atomic Force Microscopy (AFM) in molecular scale imaging of materials, we propose a laser-free AFM scheme augmented with an accurate control strategy for its scanning axes. It employs a piezoresistive sensing device with a high level of accuracy to avoid using the bulky and expensive laser interferometer. Change in the resistance of piezoelectric layer due to the deflection of microcantilever caused by the variation of surface topography is monitored through a Wheatstone bridge. Hence, it captures the surface topography without the use of laser and with nanometer scale accuracy. To improve the speed of imaging, however, a Lyapunov-based robust adaptive control strategy is implemented in the 2-DOF scanning stage. It has been demonstrated in an earlier publication that this control framework has superior performance over the conventional PID controllers typically used in commercial AFMs. The paper, then, demonstrates a set of experiments on a standard AFM calibration sample with 200 nm stepped topography. Results indicate accurate imaging of the sample up to the frequency of 30 Hz, for a 16μm×16μm scanning area, proving the feasibility of less costly and high speed AFM-based metrology.

Improving Accuracy of Sample Surface Topography by Atomic Force Microscopy

2009 ◽  
Vol 9 (10) ◽  
pp. 6003-6007 ◽  
Author(s):  
Mingsheng Xu ◽  
Daisuke Fujita ◽  
Keiko Onishi ◽  
Kunichi Miyazawa
Keyword(s):  
Atomic Force Microscopy ◽  
Surface Topography ◽  
Sample Surface ◽  
Force Microscopy ◽  
Atomic Force ◽  
Improving Accuracy

Expanding Functionality of Atomic Force Microscopy with High-Speed Environmental Studies

MRS Advances ◽  
2018 ◽  
Vol 3 (11) ◽  
pp. 587-593 ◽  
Author(s):  
Sergei Magonov ◽  
Shijie Wu
Keyword(s):  
Atomic Force Microscopy ◽  
High Resolution ◽  
Conformational Changes ◽  
High Speed ◽  
Molecular Motion ◽  
Sample Surface ◽  
High Resolution Imaging ◽  
Force Microscopy ◽  
Atomic Force ◽  
Resolution Imaging

ABSTRACTEnvironmental atomic force microscopy (AFM) study of brush macromolecules, polymer blends and bitumen was performed with regular and Quick Scan imaging. Condensation of different vapors on sample surface has induced swelling of hydrophilic domains that helps recognizing the components of heterogeneous compounds. High-resolution imaging of brush macromolecules was achieved in ethyl acetate vapor. Fast monitoring of aggregation/spreading of brush macromolecules revealed dynamics of conformational changes and molecular motion.

A Statistical Study of Process Variables to Optimize a High Speed Curtain Coater: Part I

TAPPI Journal ◽  
2009 ◽  
Vol 8 (1) ◽  
pp. 20-26 ◽  
Author(s):  
PEEYUSH TRIPATHI ◽  
MARGARET JOYCE ◽  
PAUL D. FLEMING ◽  
MASAHIRO SUGIHARA
Keyword(s):  
Boundary Layer ◽  
Experimental Design ◽  
High Speed ◽  
Statistical Study ◽  
Process Variables ◽  
High Speeds ◽  
The Stability ◽  
Air Removal ◽  
Removal System

Using an experimental design approach, researchers altered process parameters and material prop-erties to stabilize the curtain of a pilot curtain coater at high speeds. Part I of this paper identifies the four significant variables that influence curtain stability. The boundary layer air removal system was critical to the stability of the curtain and base sheet roughness was found to be very important. A shear thinning coating rheology and higher curtain heights improved the curtain stability at high speeds. The sizing of the base sheet affected coverage and cur-tain stability because of its effect on base sheet wettability. The role of surfactant was inconclusive. Part II of this paper will report on further optimization of curtain stability with these four variables using a D-optimal partial-facto-rial design.

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