Cantilever-based optical interfacial force microscope in liquid using photothermal actuation

Area of Science:

• Nanotechnology
• Surface Science
• Biophysics

Background:

• Measuring single-molecule interactions in liquid is crucial for understanding biological and chemical processes.
• Existing techniques often face limitations in resolution or applicability in aqueous environments.

Purpose of the Study:

• To develop a novel cantilever-based optical interfacial force microscope (COIFM) for precise force measurements.
• To utilize photothermal actuation for enhanced sensitivity and performance in liquid.

Main Methods:

• Developed a COIFM employing photothermal actuation of a silicon cantilever with optical detection.
• Utilized the force feedback technique for measuring single molecular interactions.
• Characterized force resolution and performed force-distance curve measurements in deionized water.

Main Results:

• Achieved a force resolution of approximately 1.5 pN in deionized water.
• Measured attractive forces of -50 pN at a 30 nm distance between probe and surface.
• Demonstrated the COIFM's capability to obtain force-distance curves on approach and retraction.

Conclusions:

• The photothermal COIFM enables direct measurement of force-distance curves in liquid environments.
• The instrument is capable of unveiling structural and mechanical information at the single molecular level.
• This technique offers a powerful tool for studying interfacial phenomena in biological and material science applications.