Capillary-Driven 3D Open Fluidic Networks for Versatile Continuous Flow Manipulation

Human civilization hinges on the capability to manipulate continuous flows. However, continuous flows are often regulated in closed-pipe configurations to address their instability, isolating the flows from the environment and considerably restricting their functionality. Manipulating continuous flows in open systems remains challenging. Here, capillary-driven 3D open fluidic networks (OFNs) composed of connected polyhedral frames are reported. Each frame acts as a fluid chamber with free interfaces that enable fluid entry and exit; the connecting rods function as valves, allowing precise control over the direction, velocity, and path of the flow. The OFNs seamlessly adapt to various fluid systems, enabling precise 3D manipulation of multiple flows. Leveraging these distinctive features, a series of applications, including selective metallization, programmable mixing and diagnostics, and spatiotemporal control of multi-step reactions, are achieved. The OFNs' free fluid interfaces also facilitate controlled drug release and efficient heat exchange. These versatile OFNs will significantly advance technological innovations in engineering, microfluidics, interfacial chemistry, and biomedicine.