Multi-frequency passive and active microrheology with optical tweezers

Area of Science:

• Biophysics
• Materials Science
• Metrology

Background:

• Optical tweezers are crucial for in vivo microrheology, assessing viscoelastic properties linked to biological health.
• Accurate force calibration is essential for optical tweezers microrheology.
• Active-passive calibration offers minimal a-priori knowledge for trap stiffness and microrheological property determination.

Purpose of the Study:

• To develop an optimized active-passive calibration technique for optical tweezers microrheology.
• To implement a more straightforward sample stage driving method compared to traditional laser driving.
• To enable precise microrheological measurements in biological systems.

Main Methods:

• Developed an optimized active-passive calibration technique using sample stage driving.
• Implemented multi-frequency driving for rapid, broad-frequency microrheological measurements.
• Validated the optical tweezers microrheometer with water, viscous, and methylcellulose solutions.

Main Results:

• Achieved microrheological measurements over a broad frequency range in seconds.
• Demonstrated accurate calibration and property determination in various media.
• Validated the method's effectiveness for complex viscoelastic samples.

Conclusions:

• The optimized active-passive calibration with sample stage driving simplifies optical tweezers microrheology.
• This technique allows for high temporal- and spatial-resolution microrheological precision metrology.
• Enables the investigation of short time-scale phenomena in biological samples.