As a result of the hard work of our project partners BRAVE Analytics and Medical University Graz, a very nice scientific publication on Physical Review Applied has been released in August 2022. It demonstrates the Optofluidic Force Induction (OF2i) scheme for real-time determination of particle size distributions with high throughput. The setup is based on the principle of optical tweezers, which was recently awarded the Nobel Prize in Physics. In combination with a higher-order laser mode, this approach allows BRAVE and MUG to infer quantities such as particle size and concentration in a parallel manner by observing particle trajectories influenced by an excitation laser.
In parallel with this paper, a focus article has also been published on the Physics magazine of APS physics on August 2022.
Schematics of the optofluidic force induction (OF2i) scheme. (a) Particles are immersed in a fluid and are pumped through a microfluidic channel. A weakly focused Laguerre-Gaussian laser beam with an OAM propagates in the same direction as the particle flow, and exerts optical forces on the nanoparticles. By monitoring the light scattered by the particles through a microscope objective, one obtains information about the scattering cross sections and via particle tracking the velocities of the individual particles. (b) Simulated trajectories for two selected particles. Because of the OAM particles move along spiral-shaped trajectories, thus suppressing collisions and particle blockage in the focus region. (c) The optical force Fopt,z and the fluidic force Ffluid,z acting on a particle control the flow in the propagation direction z, the optical force Fopt,x provides optical 2D trapping in the transverse direction x (the trapping force along y is not shown).
