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Abstract Microbubbles are an important tool due to their unique mechanical, acoustic, and dynamical properties. Yet, it remains challenging to generate microbubbles quickly in a parallel, biocompatible, and controlled manner. Here, we present an opto-electrochemical method that combines precise light-based projection with low-energy electrolysis, realizing defined microbubble patterns that in turn trigger assembly processes. The size of the bubbles can be controlled from a few to over hundred micrometers with a spatial accuracy of ~2 μm. The minimum required light intensity is only ~0.1 W/cm², several orders of magnitude lower compared to other light-enabled methods. We demonstrate the assembly of prescribed patterns of 40-nm nanocrystals, 200 nm extracellular vesicles, polymer nanospheres, and live bacteria. We show how nanosensor-bacterial-cell arrays can be formed for spectroscopic profiling of metabolites and antibiotic response of bacterial assemblies. The combination of a photoconductor with electrochemical techniques enables low-energy, low-temperature bubble generation, advantageous for large-scale, one-shot patterning of diverse particles in a biocompatible manner. The microbubble-platform is highly versatile and promises new opportunities in nanorobotics, nanomanufacturing, high-throughput bioassays, single cell omics, bioseparation, and drug screening and discovery. 

Swarming, a phenomenon widely present in nature, is a hallmark of nonequilibrium living systems that harness external energy into collective locomotion. The creation and study of manmade swarms may provide insights into their biological counterparts and shed light to the rules of life. Here, we propose an innovative mechanism for rationally creating multimodal swarms with unprecedented spatial, temporal, and mode control. The research is realized in a system made of optoelectric semiconductor nanorods that can rapidly morph into three distinct modes, i.e., network formation, collectively enhanced rotation, and droplet-like clustering, pattern, and switch in-between under light stimulation in an electric field. Theoretical analysis and semiquantitative modeling well explain the observation by understanding the competition between two countering effects: the electrostatic assembly for orderliness and electrospinning-induced disassembly for disorderliness. This work could inspire the rational creation of new classes of reconfigurable swarms for both fundamental research and emerging applications.