Torsional resonance mode atomic force microscopy in liquid with Lorentz force actuation

Area of Science:

• Atomic Force Microscopy
• Nanotechnology
• Biophysics

Background:

• Cantilevers are crucial in atomic force microscopy (AFM) for surface analysis.
• Exciting pure torsional resonances in cantilevers is challenging, especially in liquid environments.
• Developing novel excitation methods can enhance AFM sensitivity and imaging capabilities.

Purpose of the Study:

• To present a novel design for exciting pure torsional resonances in cantilevers using Lorentz force induction.
• To demonstrate the capability of this method for atomic force microscopy (AFM) imaging in air and water.
• To highlight the potential for high-speed and high-sensitivity imaging in aqueous environments.

Main Methods:

• Lorentz force induction was utilized to excite torsional resonances in various cantilever types.
• Phase-modulation torsional resonance mode was employed for atomic force microscopy (AFM) imaging.
• Force-versus-distance curves were measured using stiff cantilevers to analyze hydration layers.

Main Results:

• Pure torsional resonances were successfully excited in cantilevers in both air and water.
• Fine features of purple membranes were resolved using phase-modulation torsional resonance mode.
• Characteristic oscillatory profiles of hydration layers at a water-mica interface were detected, demonstrating high force sensitivity.

Conclusions:

• The Lorentz force induction method effectively excites pure torsional resonances in cantilevers.
• Torsional resonance mode AFM shows high force sensitivity and imaging capability in aqueous solutions.
• The developed technique holds significant potential for high-speed, high-sensitivity AFM imaging in liquids.