Join us for this exciting QUBIC Seminar Series event.

Investigating the Ballistic Regime with Rotational Optical Tweezers

Speaker: Mr Mark Watson, Optical Tweezers Group (UQ)
Date: Wednesday 7 August, 1pm – 2pm
Venue: AIBN Level 1 Seminar room, University of Queensland
Zoom: Click here to join the seminar

Abstract
The ballistic motion of single particles in liquids remains an experimental challenge that shrouds our understanding of the particle-liquid interactions on exceedingly short-time scales. Accessing the ballistic regime requires sufficient spatial-temporal resolution capable of resolving a particle’s velocity dissipation as it is driven by thermal motion. The direct measurement of rotational ballistic motion provides an intriguing avenue of research to gain new insight into hydrodynamic effects and offers an opportunity for ultrafast measurements of viscosity in systems out-of-equilibrium. This presentation describes the use of Rotational Optical Tweezers to perform high-bandwidth sensitive measurements capable of reaching the rotational ballistic regime. The polarisation-based technique provides an excellent signal-to-noise measurement that decouples the high-frequency angular motion from the optical trapping potential with minimal trapping power. This enables studies of hydrodynamic effects and fast viscometry with applications to complex biological systems.

Bio
Mark Watson is a Brisbane local and a Physics PhD candidate in the Optical Micromanipulation Group at the University of Queensland, continuing his research from his Honours degree in Biophysics at the same institution. His work focusses on utilising Rotational Optical Tweezers in novel situations, predominantly focussing on its use for intracellular microrheometry of living organisms and rotational hydrodynamics.

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