Research news

Nematic liquid crystals have complex rheological properties compared to isotropic liquids, and achieving precise flows can be difficult experimentally. In this paper, Čopar et al. demonstrate transitions a discontinuous transition from homeotropic to planar director orientation in a microfluidic channel with homeotropic boundaries as the flow rate is increased. Furthermore, they demonstrate the existence of a topologically protected intermediate state, which is chiral despite the chosen system (5CB) being achiral. The authors go on to show that small amounts of chiral dopant can break the symmetry of the system and only one handedness is observed in the intermediate state. Laser tweezers which give rise to localised heating are also employed to manipulate the flow states. It is proposed that such phenomena could be exploited technology in optical shutters, in which the state is carefully tuned by the flow rate and/or laser heating.