Imaging of viscoelastic soft matter with small indentation using higher eigenmodes in single-eigenmode...

Area of Science:

• Physics
• Materials Science
• Surface Science

Background:

• Soft viscoelastic materials exhibit deformation rate-dependent properties.
• Atomic Force Microscopy (AFM) is sensitive to tip-sample interactions.
• Amplitude-modulation AFM (AM-AFM) is commonly used for material characterization.

Purpose of the Study:

• To investigate the use of higher eigenmodes in AM-AFM for imaging soft viscoelastic materials.
• To explore methods for reducing tip-sample indentation during imaging.
• To understand the trade-offs between eigenmode order, tip velocity, and indentation.

Main Methods:

• Theoretical analysis of tip-sample forces in viscoelastic materials.
• Numerical simulations of AFM imaging with different eigenmodes.
• Experimental validation using soft viscoelastic samples.

Main Results:

• Higher eigenmodes increase tip velocity, potentially reducing indentation in viscoelastic materials.
• Increased eigenmode order also leads to lower sensitivity due to higher force constants.
• A balance exists between reduced indentation and imaging sensitivity.

Conclusions:

• Higher eigenmodes offer a strategy for reduced indentation in AM-AFM of soft viscoelastic materials.
• Careful selection of eigenmode is crucial to optimize imaging parameters.
• This approach provides a simple recipe for enhanced imaging of soft matter.