Dynamic behavior of tuning fork shear-force structures in a SNOM system.

Area of Science:

• Physics
• Materials Science
• Nanotechnology

Background:

• Piezoelectric tuning fork (TF) shear-force structures are essential for distance control in scanning near-field optical microscopy (SNOM).
• Understanding the complex dynamics of micro-TFs, optical fiber probes, and probe-surface interactions is critical for high-resolution imaging and near-field inspections.
• Existing models often do not fully capture the intricate behaviors involved in these systems.

Purpose of the Study:

• To develop a comprehensive theoretical framework for analyzing the dynamic behavior of TF-probe systems interacting with sample surfaces.
• To investigate the influence of Van der Waals forces and liquid film viscosity on probe dynamics.
• To establish the relationship between the TF-probe system's dynamic response and external forces for its application as a force sensor.

Main Methods:

• Nonlinear beam tension-bending vibration theory was applied to establish vibration equations for longitudinal and lateral directions of the TF and optical fiber probe.
• Analysis of probe-surface interactions, including Van der Waals forces, was performed.
• Linear beam-bending vibration theory was used to investigate the viscous resistance of liquid films.
• Experimental validation was conducted using a TF-probe interacting with a water film on silicon wafer.

Main Results:

• Numerical results were obtained describing the vibrational behavior of the probe approaching the sample surface.
• The viscous resistance of a water film was experimentally estimated using the developed equations.
• The relationship between the TF-probe system's dynamic response and external forces was derived, demonstrating its potential as a force sensor.

Conclusions:

• The established theoretical model accurately describes the complex dynamics of TF-probe systems.
• The study provides a method for quantifying probe-surface interactions and liquid film effects.
• The findings enable the effective utilization of TF-probe structures as sensitive force sensors in microscopy and nanotechnology.