Abstract: Due to their lightweight and flexibility, soft biomimetic robots are popular in deep-sea exploration. However, existing buoyancy materials lack optimal compatibility. This study proposes a flexible, pressure-resistant, multi-medium buoyancy module comprising a flexible cavity filled with a Hollow Glass Microsphere (HGM)-water mixture and introduces structured-grid thinking, which enables contour adaptation to complex biomimetic robot morphologies. The density and pressure resistance of the buoyancy modules were experimentally tested, and the effects of varying silicone hardness, wall thickness, and volume percentage of HGM in the mixture on the performance of the buoyancy modules were compared. The results indicate that the density of the buoyancy modules ranges from 0.751 to 0.964 g/cm3. Under a pressure of 30 MPa, the volume change rate of the buoyancy modules is between 1.74% and 2.13%. The effect of air content in the flexible cavity on buoyancy modules under high pressure was examined by comparing experimental findings with simulations.

Key words: Flexibility')">Flexibility, Buoyancy module, Pressure-resistant, Structured grid thinking