Department of Mechano-Informatics, Graduate School of Information Science and Technology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan.
Langmuir. 2010 Feb 16;26(4):2497-504. doi: 10.1021/la902779g.
Capillary force makes a liquid droplet's surface have the minimum area. If the droplet is sandwiched between two plates, it exerts capillary force on the plates. The magnitude of the force depends on the shape of the sandwiched droplet, which is in turn determined by the shape of the plates and the volume of the liquid. The liquid's shape, however, is hard to determine analytically. In this paper, the torque caused by a droplet sandwiched between two noncircular plates is experimentally and theoretically analyzed. We patterned a magnetic material on the surface of the plates and used it to apply a magnetic force to the plates. The torque on the plates was measured. The torque caused by capillary force was calculated by observing the equilibrium between the capillary force and magnetic force. We obtained approximate theoretical solutions for the liquid's shape and torque and verified that they were in accordance with the experimental results. The experimental and theoretical results presented in this paper are useful for designing microdevices or self-assemblies actuated by capillary force.
毛细作用力使液滴表面具有最小面积。如果液滴被夹在两个板之间，它会对板施加毛细作用力。力的大小取决于被夹在中间的液滴的形状，而液滴的形状又取决于板的形状和液体的体积。然而，液体的形状很难进行分析。在本文中，我们通过实验和理论分析研究了夹在两个非圆形板之间的液滴产生的扭矩。我们在板的表面上制作了一层磁性材料，并利用它对板施加磁力。测量了板上的扭矩。通过观察毛细力和磁力之间的平衡，计算出由毛细力引起的扭矩。我们得到了液体形状和扭矩的近似理论解，并验证了它们与实验结果相符。本文提出的实验和理论结果对于设计由毛细力驱动的微器件或自组装体具有重要意义。
