Droplet-Sub Lane: A Buoyancy-Driven Micro-Submarine with One-Sided Inductive Harvest Ladder

This technical note presents a compact platform for continuous energy harvesting in a liquid column using multiple buoyancy-driven “droplet submarines” traveling in a narrow vertical tube. Each sub carries an axial magnet and an onboard coil, while hugging a steel-backed wall lined with stationary harvesting coils. The system generates EMF via magnetic induction, with short charge zones at the top and bottom to replenish onboard storage. A staggered fleet of micro-subs ensures nearly continuous energy output. This buildable 20 cm reference design enables safe, tabletop demonstration of fluidic inductive systems and supports modular off-grid power development.