Bound state and hydrodynamic interaction of microrods in chiral nematic liquid crystals

In a striking departure from the pair interaction of spherical microparticles in chiral nematic liquid crystals we show that a pair of microrods form a bound state due to the competing effect of electrostatic and elastic interactions. The robustness of the bound state is demonstrated by applying external electrical and mechanical forces that perturbs their equilibrium position as well as orientation. In the bound state the microrods interact through the hydrodynamic forces which are determined from the measurements of the correlated thermal fluctuations in their position using two-particle cross-correlation spectroscopy. These findings reveal unexplored aspects of liquid-crystal dispersions which are important for understanding the assembly and dynamics of the nano and microparticles in chiral nematic liquid crystals.