A New Elementary Method for Determining the Tip Radius and Young's Modulus in AFM Spherical Indentations

Area of Science:

• Nanotechnology
• Materials Science
• Biophysics

Background:

• Atomic force microscopy (AFM) is crucial for nanoscale biological material characterization.
• Accurate Young's modulus determination relies on precise indenter tip radius calibration.
• Current calibration methods can be experimentally intensive.

Purpose of the Study:

• To introduce a simplified method for calculating the AFM indenter tip radius.
• To enable simultaneous determination of tip radius and sample Young's modulus.
• To reduce experimental effort in AFM nanoindentation studies.

Main Methods:

• Utilizing a single force-indentation curve from an unknown soft sample.
• Plotting a tangent line on the force-indentation curve at maximum indentation depth.
• Applying equations relating force, indentation depth, and tip radius.

Main Results:

• The tip radius can be accurately approximated without prior sample knowledge or separate calibration.
• Young's modulus and tip radius can be determined simultaneously from one curve.
• The method demonstrated accuracy on agarose gel samples.

Conclusions:

• A simplified, single-curve method for AFM tip radius calibration is effective.
• This approach significantly reduces experimental complexity and time.
• The technique enhances the efficiency of nanoscale biological material characterization.