Underwater magneto-driven air de-bubbler†
The accumulation and deposition of undesired air bubbles on the surface of microfluidic channels and on underwater functional systems is a major drawback, which worsens their performance. Present de-bubbling strategies are usually complex, and they require advanced tools or tedious operation protocols. In this study, we propose a flexible and easily adaptable strategy to efficiently collect, transport and evacuate the underwater deposited air bubbles by a remote stimulus using superhydrophobic ferromagnetic particles. The low surface energy of the superhydrophobic ferromagnetic particles assures the trapping of underwater air bubbles due to their underwater superaerophilicity, while the high magnetisation of the superhydrophobic ferromagnetic particles facilitates the manipulation of the formed particle-bubble system using an external magnetic field, induced by a simple permanent magnet. The properties of the system were characterised for different bubble-deposited surfaces. Remarkably, a ∼99% air bubble removal efficiency was observed in microfluidic channels, providing an easy and inexpensive strategy to address the air bubble accumulation issue faced by the microfluidic technology without integrating any advanced tools or protocols in the device.