Exploring Dynamic Non-Idealities in Multi-Frequency Atomic Force Microscopy

2012 ◽  
Author(s):  
Santiago D. Solares
Keyword(s):  
Atomic Force Microscopy ◽  
Material Property ◽  
Mitigation Strategies ◽  
Promising Technique ◽  
Dynamic Complexity ◽  
Force Microscopy ◽  
Process Dynamics ◽  
Atomic Force ◽  
Tapping Mode Afm ◽  
Nanoscale Science

Multi-frequency atomic force microscopy (AFM), in which the microcantilever is driven at more than one frequency, has emerged as a promising technique for simultaneous topographical imaging and material property mapping. While enabling significant advantages over traditional tapping-mode AFM, the greater dynamic complexity of multi-frequency AFM also requires deeper understanding on the part of the user in order to properly interpret the results obtained. This paper illustrates this challenge by exploring a few key dynamic non-idealities, which if neglected could lead to errors of interpretation. These non-ideal phenomena offer a unique opportunity for mechanical engineers to make significant contributions to nanoscale science by providing an increased understanding of the imaging process dynamics and by developing mitigation strategies for dynamics-related artifacts.

Comparison study of live cells by atomic force microscopy, confocal microscopy, and scanning electrochemical microscopy

2007 ◽  
Vol 85 (3) ◽  
pp. 175-183 ◽  
Author(s):  
Xiaocui Zhao ◽  
Nils O Petersen ◽  
Zhifeng Ding
Keyword(s):  
Atomic Force Microscopy ◽  
Confocal Microscopy ◽  
Scanning Electrochemical Microscopy ◽  
Time Lapse ◽  
Live Cells ◽  
Tapping Mode ◽  
Force Microscopy ◽  
Atomic Force ◽  
Tapping Mode Afm ◽  
Electrochemical Microscopy

In this report, three kinds of scanning probe microscopy techniques, atomic force microscopy (AFM), confocal microscopy (CM), and scanning electrochemical microscopy (SECM), were used to study live cells in the physiological environment. Two model cell lines, CV-1 and COS-7, were studied. Time-lapse images were obtained with both contact and tapping mode AFM techniques. Cells were more easily scratched or moved by contact mode AFM than by tapping mode AFM. Detailed surface structures such as filamentous structures on the cell membrane can be obtained and easily discerned with tapping mode AFM. The toxicity of ferrocenemethanol (Fc) on live cells was studied by CM in reflection mode by recording the time-lapse images of controlled live cells and live cells with different Fc concentrations. No significant change in the morphology of cells was caused by Fc. Cells were imaged by SECM with Fc as the mediator at a biased potential of 0.35 V (vs. Ag/AgCl with a saturated KCl solution). Cells did not change visibly within 1 h, which indicated that SECM was a noninvasive technique and thus has a unique advantage for the study of soft cells, since the electrode scanned above the cells instead of in contact with them. Reactive oxygen species (ROS) generated by the cells were detected and images based on these chemical species were obtained. It is demonstrated that SECM can provide not only the topographical images but also the images related to the chemical or biochemical species released by the live cells.Key words: live cells, atomic force microscopy, confocal microscopy, scanning electrochemical microscopy.

scholarly journals Assessment of Elasticity and Topography of Aspergillus nidulans Spores via Atomic Force Microscopy

2005 ◽  
Vol 71 (2) ◽  
pp. 955-960 ◽  
Author(s):  
Liming Zhao ◽  
David Schaefer ◽  
Mark R. Marten
Keyword(s):  
Atomic Force Microscopy ◽  
Aspergillus Nidulans ◽  
Fungal Spores ◽  
Protein Structures ◽  
Spore Surface ◽  
Wild Type ◽  
Adhesive Properties ◽  
Force Microscopy ◽  
Atomic Force ◽  
Tapping Mode Afm

ABSTRACT Previous studies have described both surface morphology and adhesive properties of fungal spores, but little information is currently available on their mechanical properties. In this study, atomic force microscopy (AFM) was used to investigate both surface topography and micromechanical properties of Aspergillus nidulans spores. To assess the influence of proteins covering the spore surface, wild-type spores were compared with spores from isogenic rodA + and rodA − strains. Tapping-mode AFM images of wild-type and rodA + spores in air showed characteristic “rodlet” protein structures covering a granular spore surface. In comparison, rodA − spores were rodlet free but showed a granular surface structure similar to that of the wild-type and rodA + spores. Rodlets were removed from rodA + spores by sonication, uncovering the underlying granular layer. Both rodlet-covered and rodlet-free spores were subjected to nanoindentation measurements, conducted in air, which showed the stiffnesses to be 110 ± 10, 120 ± 10, and 300 ± 20 N/m and the elastic moduli to be 6.6 ± 0.4, 7.0 ± 0.7, and 22 ± 2 GPa for wild-type, rodA + and rodA − spores, respectively. These results imply the rodlet layer is significantly softer than the underlying portion of the cell wall.

Study of Silicon Surface Roughness by Atomic Force Microscopy

1993 ◽  
Vol 324 ◽  
Author(s):  
Andrew G. Gilicinski ◽  
Rebecca M. Rynders ◽  
Scotjt E. Beck ◽  
Yale E. Strausser ◽  
James R. Stets ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Atomic Force Microscopy ◽  
Silicon Surface ◽  
Silicon Surfaces ◽  
Quality Data ◽  
Force Microscopy ◽  
Atomic Force ◽  
Power Spectral ◽  
Tapping Mode Afm ◽  
New Form

AbstractProgress is reported in developing reliable methodology for imaging silicon surfaces with the atomic force microscope (AFM). A new form of AFM, known as tapping mode AFM, has been found to provide the best quality data for surface roughness determinations. Commercially available colloidal gold spheres have been used to fabricate tip characterization standards and are used to report tip size with roughness data. Power spectral density calculations are shown to provide a useful roughness calculation based on lateral wavelength.

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