Biomimetic Dolphin-Inspired Fin Designs and Underwater Prosthetic Applications

This study synthesizes contemporary research on dolphin-based fins and applies the acquired concepts to the design of prosthetic limbs for amputee swimmers. Three specific studies are assessed, namely: 1) The fluidstructure interaction of bionic dolphin tail fins reveals that flexible fins with greater dynamic thickness at the leading edge and varying thickness profiles offer enhanced propulsion and efficiency at biologically relevant Strouhal numbers, when compared to uniform rigid non-biomechanical fins; 2) an adaptive fin featuring a shear-stiffening gel compound joint fin, which dynamically alters between relatively soft and stiff states, generates propulsion comparable to that of rigid fins while exhibiting significantly less fluctuation in the applied force; and 3) a fin emulating the stiffness gradient of a sunfish provides approximately 25 - 26% greater propulsion for a constant input power compared to a uniform stiffness control, indicating that stiffness gradients are advantageous over constant stiffness. Collectively, these studies illustrate the benefits of biomimetic fins, including tailored flexural properties, optimized geometries, variable material properties, and organized vortex shedding, which contribute to an increase in propulsion, efficiency, and stability. The latter part of the report applies these concepts to real-world instances, such as The Fin, AMP Fins, and prosthetic animals like Winter's dolphin tail, demonstrating how biomimetic fins not only enhance speed and maneuverability but also improve comfort and satisfaction for gene-reduced systems in comparison to conventional paddle-type devices. Overall, the available evidence suggests that biomimetic fin architecture represents a feasible approach for the design of next-generation underwater prosthetics.