Comparisons of amplification and frequency output of multiple manufactured gas bubbles and gas bubble clusters of different designs, configuration, and material

Previous work has shown underwater gas bubbles to be an amplification mechanism for weak-sources outputting at the bubble's Minnaert resonance. Here further work to capture bubbles in manufactured shells and cages is reported. 3-D printed resin cages with direct air–water interfaces, and rubberized shells of specified volume and resting tension and a downward facing pipe-based system, were created. The effect these have on the resonance of the amplification system and amplitude of the output is analyzed. These devices are miniscule compared to other low-frequency devices of a similar center frequency, for example, a 500-Hz cage has a 7-mm radius sphere. Another key feature explored is utilizing inter-bubble coupling at different distances, configurations, and bubble volume deltas as a means of frequency output control and the effect that the different bubble-holding systems have on this coupling. Controlling the exact frequency response of this system is important as one of the major applications for these devices will be as a finely tuned underwater sensor for weak signals in noisy environments.