Evaluation of Manipulation Probes for Expanding the Range of Capillary Force
K.J. Obata, S. Saito and K. Takahashi
Tokyo Institute of Technology, JP
micromanipulation, capillary forces, adhesion, numerical methods
It is difficult to manipulate a micro-sized object precisely with conventional tools, because the gravity effect becomes extremely small compared to the adhesional one. Therefore, in order to perform reliable micromanipulation, we need to use a force that is both controllable and greater than the adhesional force. We have proposed a manipulation method based on capillary force. For reliable micro-manipulation, a wide range of capillary force is required to pick/place a micro-object. This paper evaluates the capillary force generated by a liquid bridge between a spherical object and a manipulation probe with a concave tip. As the radius of the concavity being close to the object, the capillary force can be increased drastically, and it can also be controlled through a wide range by means of the liquid volume. There is a drastic decrease of the capillary force with the liquid volume when the hemline of the meniscus is on the brim of the concave, and it can be shifted by means of the depth control of the concavity. The mechanism of this increase of the capillary force, the capillary force curve, and the profile of the liquid bridge are also presented.
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Nanotech 2005 Conference Program Abstract