Micromanipulation method and experiments of controllable capillary force based on condensation on hydrophobic surface

On the basis of the presented micromanipulation method of condensation on hydrophobic surface, the volume of the water droplet on the hydrophobic tip surface can be dynamically varied which helps to obtain appropriate capillary lifting forces using the designed droplet micromanipulator. The single droplet growth model is established to analyze the influence of the minimum radius of droplet, the supercooling degree and the saturation temperature. Accordingly, the operational process of picking up and releasing are discussed by the theoretical models. With the assistance of a customized motion platform, the droplet formation on hydrophobic tip and the capillary lifting force generated during the manipulation process are experimentally characterized. Micromanipulation tasks of pick-and-place the micro silicon chips (1 mm×1 mm×0.52 mm, 12.1 μN) and thin-wall microspheres with diameters of 200 μm, wall thickness of 4 μm (5.069 nN) are conducted to verify the feasibility of the presented method.