Ultraclean Self‐Assembly on Micro‐Bubble Lattice

ABSTRACT Water‐based processing represents a technological solution to the safe, sustainable, and efficient fabrication and is key to advanced industries such as biomaterials, wearable electronics, and medical studies. In many of these, massive micro‐patterning adds extra functionality but demands stringent factors which are incompatible with delicate micro‐constituents. Here we show an ultraclean self‐assembly of micro‐objects on an underwater microbubble lattice generated on a surface of contrasting wettability. The water‐air interface of these gaseous receptors provides capillarity adhesion to bind micro‐objects that come into contact, leaving no tenacious residues upon subsequent transfer, which preserves objects’ original states to the fullest. Leveraging such a removable and residue‐free feature, heterogeneous micro‐objects can be coassembled through selective bubble regeneration and its biocompatibility is verified by patterning cell‐laden microgels. The air‐bridge‐mediated adhesion on a curved surface is numerically studied and two key impacting factors, wettability and particle‐to‐bubble size ratio, are extracted. Our approach enables massive patterning in an ultraclean and physico‐chemically‐benign manner and forms a part of water‐based manufacturing that bridges the initial component microfabrication and final device application.