Multi-actuation and PI control: a simple recipe for high-speed and large-range atomic force microscopy

Area of Science:

• Nanotechnology
• Surface Science
• Microscopy

Background:

• High-speed atomic force microscopy (HS-AFM) is crucial for observing dynamic nanoscale processes.
• Conventional AFM scanners face challenges in maintaining low interaction forces at high speeds.
• Existing solutions like rigid scanners limit tracking range, while multi-actuation schemes offer potential but require complex integration.

Purpose of the Study:

• To present a method for seamlessly integrating additional actuators into conventional AFMs.
• To achieve high-speed and large-range imaging capabilities with a maximally flat frequency response.
• To enable retroactive enhancement of existing AFM systems with minimal cost.

Main Methods:

• A simple control scheme is employed to manage the dynamics of individual actuators and their couplings.
• The multi-actuated setup is designed to emulate a single high-speed, large-range actuator.
• Standard Proportional-Integral (PI) controllers are adapted for high-speed imaging requirements.

Main Results:

• The proposed technique retroactively enhances a conventional AFM with a tube scanner.
• An order of magnitude improvement in closed-loop bandwidth performance is achieved while maintaining a large tracking range.
• The method demonstrates effectiveness across various sample types and imaging modes (contact and tapping, air and liquid).

Conclusions:

• The developed method provides an effective platform for retroactively enhancing existing AFMs.
• It offers a cost-effective solution for achieving high-speed and large-range imaging without compromising performance.
• This advancement facilitates the observation of dynamic nanoscale phenomena with improved fidelity.