Video-based and interference-free axial force detection and analysis for optical tweezers

Area of Science:

• Biophysics
• Nanotechnology
• Molecular dynamics

Background:

• Precise measurement of minute forces is essential for single-molecule studies.
• Optical tweezers are widely used but require careful calibration and noise reduction.

Purpose of the Study:

• To develop and validate a video-based axial force detection system for optical tweezers.
• To achieve sub-piconewton force resolution for single-molecule translocation experiments.

Main Methods:

• Integrated a CCD video camera with Allan variance analysis for trap stiffness calibration.
• Analyzed microbead backscattering properties to minimize interference.
• Developed optimized experimental configurations for microbead material and diameter.

Main Results:

• Achieved an overall force resolution of ±0.5 pN at a sample rate of 123 Hz.
• Demonstrated interference-free microbead position detection.
• Successfully investigated nanopore threading forces of single dsDNA strands.

Conclusions:

• The developed system enables precise measurement of forces during molecular translocation.
• Optimized experimental setups minimize optical interference for enhanced accuracy.
• This technology advances single-molecule biophysics research.