Abstract
In this letter, we describe a novel capillary force gripper with two nozzles for the manipulation of complex-shaped micro-objects. These nozzles rapidly form constant-volume droplets and have two primary functions: fast water refilling by capillary action and fast droplet formation by the on-off control of a diaphragm pump. Capillary force is a dominant microscopic force acting on objects of all shapes owing to the fluidity of water. Therefore, it is suitable for the capture and release of heterogeneous and complex-shaped micro-objects. In the experiments, we picked and placed 1-mm cubes, triangular prisms, and helical micro springs. The positioning errors ±SD for each shape were 54 ± 36 μm, 85 ± 32 μm, and 162 ± 74 μm, respectively. These prisms and springs are difficult to control using conventional air nozzles, which have a typical positioning accuracy of approximately ± 40 μm for rectangular prismatic objects. In addition, by setting the distance between the nozzles to an appropriate value, we reduced the deviation of the attitude angle around the vertical axis to ±2.6° using self-alignment phenomena for the 1-mm cubes. The proposed method is feasible for manipulating complex-shaped and fragile micro-objects in the micro-electro-mechanical systems field.
Highlights
THE fields of automotive engineering, optics, electronics, and medicine have experienced extensive miniaturization and increasing sophistication of products with the development of micro-manufacturing technologies
In conventional commercially available surface mounting technology, the suction force generated by compressed air is primarily used for one-by-one pick-and-place rectangular prismatic components with a mounting accuracy of ±40 μm
The capillary force is geometrically determined if the section curves of the meniscus are approximated as parts of the arc [15]
Summary
THE fields of automotive engineering, optics, electronics, and medicine have experienced extensive miniaturization and increasing sophistication of products with the development of micro-manufacturing technologies. A capillary force-based gripper (capillary force gripper) is a possible grasping method for picking and placing complex and fragile components, it is not suitable for hygroscopic materials and substances subject to water corrosion It is used as an active release method with a self-alignment function caused by the minimization of the surface energy of the liquid [15,16,17,18,19,20]. A capillary force gripper developed by Hagiwara et al sustained a liquid bridge for more than 150 s by preventing the vaporization of water [18] Their attempts to pick and place 1 mm-sized complex shapes, such as semicircular prisms and triangular pyramids, had a success rate of approximately 70% and 60%, respectively, and the positioning error was greater than 200 μm, 20% of the length of the object.
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