Interpreting atomic force microscopy measurements of hydrodynamic and surface forces with nonlinear parametric...

Area of Science:

• Surface science and nanotechnology
• Fluid dynamics and hydrodynamics
• Materials characterization

Background:

• Atomic force microscopy (AFM) is crucial for probing forces at the nanoscale.
• Understanding surface forces and cantilever properties is essential for accurate AFM measurements.
• Hydrodynamic interactions can influence force measurements, especially at varying velocities.

Purpose of the Study:

• To develop a nonlinear parameter estimation method for extracting surface forces and cantilever spring constants from AFM data.
• To leverage velocity-dependent hydrodynamic interactions for unbiased surface force estimation.
• To quantify hydrodynamic slip in colloidal probe-plate interactions.

Main Methods:

• Nonlinear parameter estimation applied to AFM force-displacement data.
• Utilizing data collected at multiple interaction speeds.
• Analyzing the velocity dependence of force-displacement curves to account for hydrodynamic effects.
• In situ estimation of cantilever spring constant.

Main Results:

• Successfully extracted separation-dependent surface forces without assuming a functional form.
• Obtained consistent estimates of the in situ cantilever spring constant.
• Quantified hydrodynamic slip by combining dynamic and static force measurements.

Conclusions:

• The developed method provides an unbiased estimation of surface forces by incorporating hydrodynamic interactions.
• The technique allows for simultaneous determination of surface forces and cantilever properties.
• This approach offers a robust way to study fluid dynamics at the nanoscale and quantify hydrodynamic slip.