A new conceptual method termed as suspension 3D printing is demonstrated using self‐healing hydrogel support to create macroscopic structures of liquid metal that exhibits properties indicative of a nonprintable object. The relationships between the process parameters, supporting gel concentration, and the deposited microdroplet geometry are clarified. The smaller nozzle inner diameter, lower flow rate, and higher printing speed will lead to a smaller droplets size. The gel concentration plays a significant role on patterning the droplets space. The results presented can be applied to design the target feature and further optimize the input parameters. Besides, this paper also illustrates the capability and potential application of the method in constructing 3D macrostructures and stereo electronic systems using these liquid metal droplets. Based on this strategy, it is possible to print liquid metal into sophisticated multidimensional and shape transformable functional structures ignoring the effects of fluid instability, gravity, and surface tension. Furthermore, this work can help remove the limits of materials and technical barriers to enable a wide variety of materials to be printed into arbitrary shapes. It is expected that further practices of the methodology will facilitate the advancements in multiscale droplets generation, flexible electronics, encapsulation technologies, biology and medicine, etc.

A low voltage 3D parallel electroosmotic flow (EOF) pump composed of two electrode layers and a fluid layer is proposed in this work. The fluid layer contains twenty parallel fluid channels and is set at the middle of the two electrode layers. The distance between fluid and electrode channels was controlled to be under 45 μm, to reduce the driving voltage. Room temperature liquid metal was directly injected into the electrode channels by syringe to form non-contact electrodes. Deionized (DI) water with fluorescent particles was used to test the pumping performance of this EOF pump. According to the experimental results, a flow rate of 5.69 nL/min was reached at a driving voltage of 2 V. The size of this pump is small, and it shows a great potential for implanted applications. This structure could be easily expanded for more parallel fluid channels and larger flow rate.