Abstract
For a thermotropic liquid crystal, its phase state depends on temperature, and nematic and isotropic phases, which behave like a fluid macroscopically, can coexist by adjusting its temperature. We have developed a liquid-like micromanipulator operated by a phase interfacial force induced between nematic and isotropic phases of a liquid crystal. In this experiment, we have used 4-cyano-4'-pentyl biphenyl as a thermotropic liquid crystal, mixed microparticles with the diameter of 9 - 30 μm in the liquid crystal, and controlled the temperature distribution of the liquid crystal sandwiched between two glass plates by two sets of Peltier devices. The moving speed of a phase interface decreased linearly with increasing the temperature of the higher-temperature Peltier devices. We have tried to manipulate the particles in the liquid crystal by moving a phase interface. The particles are successfully driven only for the case that the area of nematic phase expands, and the maximum phase interfacial force is evaluated through the motion equation of a particle to get 1.4 nN. It is also found that the interfacial force is independent of the size of particles, which is explainable qualitatively on the basis of the deformation of molecular orientation field in the nematic phase due to the presence of particles.
