Measurement sensitivity improvement in tapping-mode atomic force microscopy through bi-harmonic drive signal

Area of Science:

• Surface Science
• Nanotechnology
• Microscopy

Background:

• Tapping-mode atomic force microscopy (AFM) is a crucial technique for nanoscale imaging.
• Current methods face limitations in measurement sensitivity and tip-sample impact forces.
• Optimizing tip-sample interaction is key to improving AFM performance.

Purpose of the Study:

• To develop a novel method for enhancing measurement sensitivity in tapping-mode AFM.
• To reduce impact forces during tip-sample interactions.
• To improve the sharpness and durability of AFM imaging.

Main Methods:

• Reshaping the tip trajectory using a bi-harmonic tapping drive signal.
• Generating an oscillating trajectory with a broader valley compared to sinusoidal trajectories.
• Utilizing numerical simulations and experimental validation.

Main Results:

• The bi-harmonic trajectory significantly reduces tip velocity near the sample surface.
• Increased portion of each oscillation period spent near the sample.
• Demonstrated decrease in impact force and enhanced sensitivity to tip-sample offset.
• Observed improvements in image sharpness and reduced tip wear.

Conclusions:

• The bi-harmonic driving signal offers a superior approach for tapping-mode AFM.
• This method effectively enhances measurement sensitivity and minimizes tip-sample impact.
• The technique leads to higher quality AFM images and prolonged tip lifespan.