Boundary Guided Liquid-Bridge Adhesion for Robotic Pick-and-Release.

Liquid-bridge-mediated adhesion provides conformal contact with rough surfaces and gentle interaction with fragile microstructures, making it attractive for object manipulation. However, controlling liquid-bridge formation and retraction under non-ideal interfacial conditions remains challenging. Here, we report a switchable liquid-bridge adhesion strategy using a two-tiered stamp with spatially patterned wettability. Boundary-guided pinning confines liquid spreading to form a stable bridge for pickup and guides liquid retraction toward bridge breakup for controlled release. This design converts liquid-bridge adhesion from an uncontrolled capillary phenomenon into a controllable interfacial mechanism. The strategy enables preload-free adhesion switching, tunable adhesion forces, robust manipulation across surfaces with diverse roughness and wettability, and damage-free contact with fragile microstructures. Integrated with a robotic platform, the stamp functions as a liquid-bridge-based robotic end effector for pick-and-place manipulation and robotic placement, providing a route toward ultra-gentle manufacturing and microelectronic assembly.