Adaptive Tweezers Based on Differential Hydrophilic–Hydrophobic Surfaces for the Manipulation of Micro-Objects

Conventional micromanipulation techniques, such as optical capture and mechanical grippers, suffer from rigid contact damage and exhibit poor adaptability to objects with diverse masses. This research presents adaptive droplet tweezers featuring nonparallel structures to tackle the nondestructive micromanipulation of objects with different masses. Through the analysis of the mechanical equilibrium conditions of the liquid bridge (where the pressures on the upper and lower surfaces of the bridge are equivalent), the critical parameters for a stable liquid bridge, including the contact angle, opening distance, and height, were discussed. The results of this study suggest that pulling of the tweezers and increasing the lower opening distance of the end of droplet tweezers are conducive to object transfer. Subsequent experiments conducted on the experimental platform verified the principles. Ultimately, by adjusting the curvature of the droplet bridge structure according to the hydrophilic-hydrophobic differences, the handling of objects with different weights was accomplished. This research demonstrates that the adaptive liquid bridge structure effectively surmounts the limitations of traditional methods, offering a novel approach for the flexible and adaptive micromanipulation of microscale objects.