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Extending calibration-free force measurements to optically-trapped rod-shaped samples
Frederic Català1,2, Ferran Marsà2,3, Mario Montes-Usategui1,2
1Optical Trapping Lab - Grup de Biofotònica, Departament de Física Aplicada, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain.
Scientific Reports
|February 22, 2017
Summary
This study introduces a calibration-free method using holographic optical tweezers to measure forces on rod-shaped biological samples. This technique accurately detects drag forces, aiding microscale biological research.
Area of Science:
- Biophysics
- Optical Tweezers
- Microscale Force Measurement
Background:
- Optical trapping is vital for microscale biological research, enabling non-invasive force measurements.
- Accurate force quantification in optical traps requires precise calibration, challenging for diverse sample geometries.
- Elongated biological specimens (e.g., bacteria, chromosomes) often necessitate multiple traps, complicating force determination.
Purpose of the Study:
- To develop a calibration-free method for accurate force measurement in optical traps.
- To address the challenge of measuring forces on elongated, rod-shaped biological samples.
Main Methods:
- Utilized holographic optical tweezers to manipulate glass microcylinders.
- Employed calibration-free direct detection of beam momentum for force measurement.
- Compared experimental results with slender-body hydrodynamic theoretical calculations.
Main Results:
- Demonstrated accurate measurement of drag forces on microcylinders without trap calibration.
- Achieved excellent agreement between experimental data and hydrodynamic theory.
- Validated a novel force-sensing approach for rod-shaped specimens.
Conclusions:
- The developed method offers a reliable way to measure forces on elongated biological samples.
- This technique has significant potential for advancing quantitative studies in microscale biophysics.
- Calibration-free force sensing using beam momentum is a promising tool for biological research.
