scholarly journals Friction and Mechanical Properties of AFM-Scan-Induced Ripples in Polymer Films

2021 ◽  
Vol 7 ◽  
Author(s):  
Sebastian Friedrich ◽  
Brunero Cappella
Keyword(s):  
Mechanical Properties ◽  
Polymer Films ◽  
Mechanical Response ◽  
Butyl Methacrylate ◽  
Clear Correlation ◽  
Contact Mode ◽  
Cantilever Deflection ◽  
Atomic Force ◽  
Volume Measurements ◽  
Force Volume

When compliant samples such as polymer films are scanned with an atomic force microscope (AFM) in contact mode, a periodic ripple pattern can be induced on the sample. In the present paper, friction and mechanical properties of such ripple structures on films of polystyrene (PS) and poly-n-(butyl methacrylate) (PnBMA) are investigated. Force volume measurements allow a quantitative analysis of the elastic moduli with nanometer resolution, showing a contrast in mechanical response between bundles and troughs. Additionally, analysis of the lateral cantilever deflection when scanning on pre-machined ripples shows a clear correlation between friction and the sample topography. Those results support the theory of crack propagation and the formation of voids as a mechanism responsible for the formation of ripples. This paper also shows the limits of the presented measuring methods for soft, compliant, and small structures. Special care must be taken to ensure that the analysis is not affected by artefacts.

scholarly journals Quantitative Nanomechanical Mapping of Polyolefin Elastomer at Nanoscale with Atomic Force Microscopy

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Shuting Zhang ◽  
Yihui Weng ◽  
Chunhua Ma
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Mechanical Response ◽  
Adhesion Force ◽  
Time Dependent ◽  
Surface Adhesion ◽  
Force Microscopy ◽  
Mechanics Model ◽  
Atomic Force ◽  
Force Volume

AbstractElastomeric nanostructures are normally expected to fulfill an explicit mechanical role and therefore their mechanical properties are pivotal to affect material performance. Their versatile applications demand a thorough understanding of the mechanical properties. In particular, the time dependent mechanical response of low-density polyolefin (LDPE) has not been fully elucidated. Here, utilizing state-of-the-art PeakForce quantitative nanomechanical mapping jointly with force volume and fast force volume, the elastic moduli of LDPE samples were assessed in a time-dependent fashion. Specifically, the acquisition frequency was discretely changed four orders of magnitude from 0.1 up to 2 k Hz. Force data were fitted with a linearized DMT contact mechanics model considering surface adhesion force. Increased Young’s modulus was discovered with increasing acquisition frequency. It was measured 11.7 ± 5.2 MPa at 0.1 Hz and increased to 89.6 ± 17.3 MPa at 2 kHz. Moreover, creep compliance experiment showed that instantaneous elastic modulus E1, delayed elastic modulus E2, viscosity η, retardation time τ were 22.3 ± 3.5 MPa, 43.3 ± 4.8 MPa, 38.7 ± 5.6 MPa s and 0.89 ± 0.22 s, respectively. The multiparametric, multifunctional local probing of mechanical measurement along with exceptional high spatial resolution imaging open new opportunities for quantitative nanomechanical mapping of soft polymers, and can potentially be extended to biological systems.

scholarly journals Mechanical response of adherent giant liposomes to indentation with a conical AFM-tip

Soft Matter ◽  
2015 ◽  
Vol 11 (22) ◽  
pp. 4487-4495 ◽  
Author(s):  
Edith Schäfer ◽  
Marian Vache ◽  
Torben-Tobias Kliesch ◽  
Andreas Janshoff
Keyword(s):  
Mechanical Properties ◽  
Atomic Force Microscopy ◽  
Mechanical Response ◽  
Force Microscopy ◽  
Atomic Force

Mechanical properties of giant liposomes with actin cortices are determined with atomic force microscopy.

The Adaptive Piezoelectric Microsensoriactuator for Active Control of Microcantilevers

2004 ◽  
Author(s):  
Steven Robert Burns ◽  
Daniel G. Cole ◽  
Robert L. Clark
Keyword(s):  
Mechanical Response ◽  
Contact Mode ◽  
Force Microscopy ◽  
Atomic Force ◽  
Resonance Response ◽  
Surface Image ◽  
The Difference ◽  
Micro Cantilever ◽  
Structure Sensor ◽  
Analog Circuitry

The adaptive piezoelectric sensoriactuator is modified for use at the microscale to facilitate non-contact mode imaging of a microcantilever MEMS device in atomic force microscopy. The sensoriactuator is a truly colocated (sensor and actuator occupy exactly the same position on the structure) sensor/actuator device that uses a hybrid digital and analog design to drive a structure while simultaneously sensing the mechanical response. Using a piezoelectric material to both sense and actuate simultaneously is problematic because of the difficulty in resolving the sensory (mechanical) and actuator (electrical) parts of the output signal. Implementation of the adaptive piezoelectric sensoriactuator at the microscale results in a system with electrical quantities that are vastly reduced or increased from typical macroscale values, requiring more precise components and more careful design and construction of analog circuitry. For example, a typical micro-cantilever piezoelectric has a capacitance of on the order of 100 pF with an impedance at 50 kHz nearly 32 kΩ. The signal levels are significantly smaller with a typical piezoelectric current on the order of 100 nA. Thus, environmental noise can overwhelm signals in the system mandating the use of high precision operational amplifiers featuring ultra-low bias currents (±30 fA) and careful guarding or shielding of all circuitry. As reported in this paper, the adaptive piezoelectric microsensoriactuator has been successfully used to simultaneously sense and actuate while imaging using non-contact mode. The self-sensing microcantilever was successfully tested to produce a surface image using the microsensoriactuator to measure the movement of the microcantilever. The RMS value of the microsensoriactuator output is compared with the desired RMS output and the difference is used to drive an active resonance response controller. The active resonance response controller determines the control signal required to augment or attenuate the microcantilever’s motion to match the desired motion.

scholarly journals Morphological and Mechanical Properties of Electrospun Polycaprolactone Scaffolds: Effect of Applied Voltage

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 662
Author(s):  
L.A. Can-Herrera ◽  
A.I. Oliva ◽  
M.A.A. Dzul-Cervantes ◽  
O.F. Pacheco-Salazar ◽  
J.M. Cervantes-Uc
Keyword(s):  
Mechanical Properties ◽  
Tissue Engineering ◽  
Surface Area ◽  
Applied Voltage ◽  
Pore Volume ◽  
Morphological Changes ◽  
Tensile Tests ◽  
Clear Correlation ◽  
Force Microscopy ◽  
Atomic Force

The aim of this work is to investigate the effect of the applied voltage on the morphological and mechanical properties of electrospun polycaprolactone (PCL) scaffolds for potential use in tissue engineering. The morphology of the scaffolds was characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), and the BET techniques for measuring the surface area and pore volume. Stress-strain curves from tensile tests were obtained for estimating the mechanical properties. Additional studies for detecting changes in the chemical structure of the electrospun PCL scaffolds by Fourier transform infrared were performed, while contact angle and X-ray diffraction analysis were realized for determining the wettability and crystallinity, respectively. The SEM, AFM and BET results demonstrate that the electrospun PCL fibers exhibit morphological changes with the applied voltage. By increasing the applied voltage (10 to 25 kV) a significate influence was observed on the fiber diameter, surface roughness, and pore volume. In addition, tensile strength, elongation, and elastic modulus increase with the applied voltage, the crystalline structure of the fibers remains constant, and the surface area and wetting of the scaffolds diminish. The morphological and mechanical properties show a clear correlation with the applied voltage and can be of great relevance for tissue engineering.

COMBINED ATOMIC FORCE AND FLUORESCENCE MICROSCOPIES TO MEASURE SUBCELLULAR MECHANICAL PROPERTIES OF LIVE CELLS

2013 ◽  
Vol 13 (04) ◽  
pp. 1350057 ◽  
Author(s):  
CHENG-TAO CHANG ◽  
CHOU-CHING K. LIN ◽  
MING-SHAUNG JU
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Elastic Properties ◽  
Previous Method ◽  
Live Cell ◽  
Live Cells ◽  
Cellular Functions ◽  
Atomic Force ◽  
Force Volume ◽  
The Relationship

Atomic force microscopy (AFM) has been widely applied to study cellular functions;however, the relationship between cellular elasticity and ultrastructure density of a live cell remains to be discovered. The objective of this study was thus to extend our previous method of integrating AFM and immunofluorescence imaging to measure the ultrastructure distribution-related local mechanical properties of live cells. First, the morphology of a live cell was obtained by AFM. Second, the indentation sites were selected and flexible force volume indentation was performed. Third, the immunofluorescence image of the cell was obtained. The last was the mapping of the indentation site to the immunofluorescence image and obtaining the relationship between the local elastic properties and cytoskeleton density. The results on differentiated rat Schwann cells (RSCs) showed that the elastic modulus of stress fibers is higher than those of the nucleus and cytosol. The local elastic modulus of the live RSCs is correlated to the actin density, and the stress fiber that behaves like a pretension beam can give RSCs enough strength to envelop axons during myelination. In particular, the elastic properties of the live RSCs were twofold lower than those of the fixed. The results demonstrated the integrated method's applicability for a live cell.

Mechanical Response of Diamond at Nanometer Scaes: Diamond Polishing and Atomic Force Microscopy

2000 ◽  
Vol 649 ◽  
Author(s):  
Ruben Pérez ◽  
Murray R. Jarvis ◽  
Michael C. Payne
Keyword(s):  
Chemical Nature ◽  
Mechanical Response ◽  
Normal Force ◽  
Single Atom ◽  
Mechanical Interaction ◽  
Contact Mode ◽  
Diamond Surfaces ◽  
Force Microscopy ◽  
Atomic Force ◽  
Diamond Polishing

ABSTRACTTotal energy pseudopotential methods are used to study two different processes involving the mechanical interaction of diamond nanoasperities and diamond surfaces: the wear processes reponsible for diamond polishing, an the mechanical deformation of tip and surface during the operation of the Atomic Force Microscope in contact Mode (CM-AFM). The strong asymmetry in the rate of polishing between different dirctions onthe diamond (110) surface is explained in terms of on atomistic mechanism for nano-groove formation. The pst–polishing surface morphology and the nature of the polishing residue epredicted by this mechanism are consistent with experimental evidence. In the case of CM-FAM, our calculations show that a tip terminated in a single atom is able to sustain forces in excess of 30 nN. The magnitude of the normal force was unexpectedlyfound to be verye similar for th approach on top of an atom or on a hollow position on the surface. This behaviour is due to tip relaxations induced by the interaction with the surface. These forces are also rather insensitive to the chemical nature of the tip apex.

scholarly journals Time- and Zinc-Related Changes in Biomechanical Properties of Human Colorectal Cancer Cells Examined by Atomic Force Microscopy

Biology ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 468
Author(s):  
Maria Maares ◽  
Claudia Keil ◽  
Leif Löher ◽  
Andreas Weber ◽  
Amsatou Andorfer-Sarr ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Mechanical Properties ◽  
Atomic Force Microscopy ◽  
Cell Lines ◽  
Mechanical Response ◽  
Cultured Cells ◽  
Force Microscopy ◽  
Atomic Force ◽  
The Impact ◽  
Ht 29

Monitoring biomechanics of cells or tissue biopsies employing atomic force microscopy (AFM) offers great potential to identify diagnostic biomarkers for diseases, such as colorectal cancer (CRC). Data on the mechanical properties of CRC cells, however, are still scarce. There is strong evidence that the individual zinc status is related to CRC risk. Thus, this study investigates the impact of differing zinc supply on the mechanical response of the in vitro CRC cell lines HT-29 and HT-29-MTX during their early proliferation (24–96 h) by measuring elastic modulus, relaxation behavior, and adhesion factors using AFM. The differing zinc supply severely altered the proliferation of these cells and markedly affected their mechanical properties. Accordingly, zinc deficiency led to softer cells, quantitatively described by 20–30% lower Young’s modulus, which was also reflected by relevant changes in adhesion and rupture event distribution compared to those measured for the respective zinc-adequate cultured cells. These results demonstrate that the nutritional zinc supply severely affects the nanomechanical response of CRC cell lines and highlights the relevance of monitoring the zinc content of cancerous cells or biopsies when studying their biomechanics with AFM in the future.

Mapping of mechanical properties of the surface by utilization of torsional oscillation of the cantilever in atomic force microscopy

Open Physics ◽  
2011 ◽  
Vol 9 (2) ◽  
Author(s):  
Andrzej Sikora ◽  
Lukasz Bednarz
Keyword(s):  
Mechanical Properties ◽  
Atomic Force Microscopy ◽  
Torsional Oscillation ◽  
Dynamic Mode ◽  
Contact Mode ◽  
Force Microscopy ◽  
Complex Information ◽  
Atomic Force ◽  
Phase Images ◽  
Time Regime

AbstractThe measurement of the surface topography in dynamic mode (intermittent contact mode) is one of the most popular ways of imaging surfaces at nanoscale with atomic force microscopy. It also allows obtaining so called phase images which reveal the viscous-elastic non-homogeneities of the surface, therefore can be used for detecting the presence of different materials. It is, however, very difficult to interpret the phase map due to the origin of phenomena, method of signal detection and processing. Therefore one cannot determine whether the observed feature is caused by increase or decrease of any of specific mechanical properties of the surface. In this article we present the modified setup of commercially available AFM, where detection of torsional oscillation of the cantilever is used for the determination of mechanical properties such as: elasticity, adhesion, peak force and energy dissipation. By advanced signal processing, the reconstruction of the force spectroscopy curve and the calculation of mentioned parameters are performed. All the operations are done in real time regime. The developed method allows one to obtain much more complex information about measured surface. Test measurement results are also presented.

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