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Accurate height and volume measurements on soft samples with the atomic force microscope.
Yuekan Jiao1, Tilman E Schäffer
1Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Am Fassberg 11, 37077 Göttingen, Germany.
Langmuir : the ACS Journal of Surfaces and Colloids
|November 3, 2004
Summary
Force mapping mode provides accurate atomic force microscope (AFM) measurements for soft samples. Unlike contact and tapping modes, it is independent of imaging force, ensuring reliable height and volume data for biological specimens.
Area of Science:
- Biophysics
- Materials Science
- Cell Biology
Background:
- Atomic Force Microscopy (AFM) is crucial for nanoscale imaging.
- Accurate quantitative measurements of soft biological samples remain challenging.
- Common AFM modes may introduce variability in measurements.
Purpose of the Study:
- To evaluate AFM imaging modes for precise height and volume quantification.
- To compare contact, tapping, and force mapping modes on soft samples.
- To identify the optimal AFM mode for reproducible soft sample measurements.
Main Methods:
- Investigated three AFM modes: contact, tapping, and force mapping.
- Measured rehydrated human metaphase chromosomes in liquid.
- Analyzed the dependence of measurements on imaging setpoint/force.
Main Results:
- Contact and tapping modes showed significant deviations (up to 50%) based on imaging force.
- Force mapping mode provided reproducible height and volume measurements.
- Force mapping results were independent of the applied imaging force.
Conclusions:
- Force mapping mode is superior for accurate and reproducible AFM measurements of soft samples.
- Contact and tapping modes are less suitable for quantitative analysis of soft biological materials.
- Recommend force mapping for precise height and volume determination of delicate specimens.