Passive Vacuum Regeneration for Suction-Based Marine Adhesion Devices

Marine data collection devices, such as audio recording tags for marine mammals, must robustly adhere to the skin of the animal using noninvasive attachment mechanisms. As such, devices for studying whale behavior and vocalization typically rely on suction cups. However, suction adhesion exhibits limited attachment duration due to the fragile nature of the cup seal on the surface of interest, reducing useful data collection time compared with more invasive methods. This study introduces a novel passive vacuum regeneration system for suction cups, powered by changes in pressure as the whale dives, to extend tag attachment time. The system uses two cylinders with linked pistons. One cylinder, hermetically sealed, drives the system using variations in external pressure during dives, while the other cylinder, linked to one-way valves, acts as a diaphragm pump, allowing fluid transfer from the suction cup to the external medium. Experimental results showed significant vacuum regeneration, achieving up to 881$\%$ for pumping a suction cup filled with air and 48.4$\%$ for one filled with water. A theoretical model identified promising designs that increase pressure regeneration by increasing the cylinder stroke and the offset between pistons. Overall, these findings suggest that the proposed system can significantly extend data collection periods, paving the way for more effective and robust marine data collection.