Controlled Movement of a Smart Miniature Submarine at Various Interfaces

Smart miniaturized aquatic devices have many important applications, but their locomotion at different interfaces remains a challenge. Here, we report a smart miniaturized submarine moving at various air/liquid or oil/water interfaces. The microsubmarine is fabricated by a CO2-responsive superhydrophobic copper mesh and is driven by the Marangoni effect. The microsubmarine can not only transfer among different interfaces reversibly but also move horizontally at the interfaces freely. The unique locomotion of the device is attributed to a CO2-triggered switch between superhydrophobicity and underwater superoleophobicity. Moreover, the microsubmarine exhibits good stability and excellent oil repellence at the oil/water interface. Our study provides a strategy for fabricating smart aquatic devices that have potential applications in environment monitoring, water purification, channel-free microfluidics, and so on.