Maglev-like droplet-based transporters co-regulated by wettability and magnetic field

The adhesion behavior of liquid droplets on solid surfaces is critical for natural transportation and industrial production. In particular, microrobots based on adhesion at solid-liquid interfaces have important applications in chemical reactions, cargo transport, and energy harvesting. However, current droplet-based manipulation strategies primarily depend on the structures or reactions between solid-liquid interfaces to achieve programmable droplets movement, while robust carrying capacity and precise synergistic operation of multiple droplets remain challenging. Herein, we propose a maglev-like droplet-based transporter system (MDTs) with adjustable structures to achieve precise droplets manipulation for robust cargo transportation and energy conversion. By controlling the magnetic fields and the droplet adhesion at the solid-liquid interfaces, the MDTs can precisely transport, climb and rotate, as well as efficiently convert mechanical energy into electricity for motion monitoring and self-powered devices. These findings deepen the understanding of force transport co-directed by surface wettability and magnetic fields, and broaden the utilization of these systems for cargo transportation and energy conversion, offering a great potential for contactless blind operation, lossless transfer and reactions, and powerless micro-electromechanical systems (MEMS).