University of Cambridge > > BSS Formal Seminars > Laser Manipulation in Liquid Crystals: an approach to microfluidics and micromachines

Laser Manipulation in Liquid Crystals: an approach to microfluidics and micromachines

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If you have a question about this talk, please contact Dr Kalin Dragnevski.

Laser trapping of particles in three-dimensions can occur as a result of the refraction of strongly focused light through micron-sized particles. The use of this effect to produce laser tweezers is extremely common in fields such as biology, but it is only relatively recently that the technique has been applied to liquid crystals. The possibilities are exciting: droplets of liquid crystals can be trapped, moved and rotated in an isotropic fluid medium, or both particles and defects can be trapped and manipulated within a liquid crystalline medium. This talk considers both possibilities. The mechanism of transfer of optical angular momentum from circularly polarised light to small droplets of nematic liquid crystals is described. Further, it is shown that droplets of chiral liquid crystal can be made to rotate when illuminated with linearly polarised light and possible mechanisms are discussed. The trapping and manipulation of micron sized particles in an aligned liquid crystal medium is used to provide a measure of local shear viscosity coefficients and a unique test of theory at low Erickson number in liquid crystals.

This talk is part of the BSS Formal Seminars series.

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