Lapointe C, Hultgren A, Silevitch D M, Felton E J, Reich D H, Leheny R L
Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 USA.
Science. 2004 Jan 30;303(5658):652-5. doi: 10.1126/science.1092608.
Anisotropic particles suspended in a nematic liquid crystal disturb the alignment of the liquid crystal molecules and experience small forces that depend on the particles' orientation. We have measured these forces using magnetic nanowires. The torque on a wire and its orientation-dependent repulsion from a flat surface are quantitatively consistent with theoretical predictions based on the elastic properties of the liquid crystal. These forces can also be used to manipulate submicrometer-scale particles. We show that controlled spatial variations in the liquid crystal's alignment convert the torque on a wire to a translational force that levitates the wire to a specified height.
悬浮在向列型液晶中的各向异性颗粒会扰乱液晶分子的排列，并受到取决于颗粒取向的微小力。我们使用磁性纳米线测量了这些力。纳米线上的扭矩及其与平面的取向相关排斥力在定量上与基于液晶弹性特性的理论预测一致。这些力还可用于操纵亚微米级颗粒。我们表明，液晶排列中受控的空间变化会将纳米线上的扭矩转换为平移力，使纳米线悬浮到指定高度。
