Bio-sensors implanted in the body are revolutionizing healthcare. How to power these sensors is an open challenge. One promising option is to harvest small amounts of energy from the body itself, effectively making the sensor self-powered. We derived and tested a model for a self-powered sensing in a human airway, where measuring subtle changes in breathing could, e.g., trigger early interventions for patients with severe asthma.
When fish-like robots tune their stiffness in realtime, they can be much more efficient. Real fish use the same strategy. In this review article, we summarize the latest work on tunable stiffness—both in the fish biology community and the bio-robotics community.
Fish are thought to adjust their tail stiffness to swim efficiently over a wide range of speeds, but how they tune stiffness has been a mystery. We derived a model that combines fluid dynamics and bio-mechanics to reveal that muscle tension should scale with swimming speed squared. By applying our strategy to a fish-like robot, we were able to nearly double its efficiency.
Animals and bio-inspired robots can swim/fly faster near solid surfaces like the seafloor. In the past, researchers had quantified how strong these effects were for two-dimensional airfoils. We studied how these results extend to the three-dimensional fins. We found that lowering the aspect ratio weakens the effect of the surface: thrust enhancements become less noticeable, stable equilibrium altitudes shift lower and become weaker, and wake asymmetries become less pronounced. (This work was done in collaboration with the Biofluids Research Lab at Lehigh University.)
We developed a model that estimates how thrust and efficiency change as a pitching hydrofoil gets closer to a planar boundary. Our model predicts that the modified forces are caused by an increasing amount of virtual mass and an increasingly distorted wake. We validated the model by comparing with water channel experiments and inviscid flow simulations. (This work was done in collaboration with the Biofluids Research Lab at Lehigh University.)