Type of thesis
Towards a biomimetic soft robotic total artificial heart
Scientific disciplinary sector
Istituto di Biorobotica - BIOROBOTICS
relatore Dott. CIANCHETTI, MATTEO
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Exam session start date
Since the early 30s, researchers have been tirelessly looking for a definitive solution to heart failure. Although the efforts, the present artificial devices still need a continuous anticoagulation therapy to avoid thromboembolism, while risking to fall into bleeding complications. Soft robotics technologies have recently shown their advantages within the biomedical field: compliance, biomimetism and safe interaction with body tissues seem to be the key features to design innovative and safe biomedical devices. This doctoral thesis presents the work performed towards the development of a biomimetic soft robotic total artificial heart. Taking inspiration from the natural disposition of the cardiac fibres, the envisioned device couples the action of a deformable blood chamber and a double layer of artificial muscles, wrapped in a counteracting helix around it. Given a particular semi-ellipsoidal geometry of bioinspired dimensions, the system was modelled analytically to obtain an indication of the most efficient orientation of the actuators. The results showed an incredible similarity with the myocardial fibres arrangement. The artificial muscles were characterized, and different prototypes were fabricated to select the best performing combination of materials. In parallel to the FEM simulations run in collaboration with colleagues, all the prototypes were statically tested with different protocols. The best results were obtained by employing a semi-ellipsoidal 1.5 mm thick chamber casted with Smooth-Sil 950 (Smooth-on! Inc.), and twelve McKibben actuators characterized by a 3 mm inner diameter and an aramid braided sleeve with a diameter of 5 mm and 14 mm, in respectively unpressurized and pressurized states. This prototype demonstrated an ejection fraction ranging from 44% up to 69%, with an actuating pressure of 120 kPa and an afterload of 90mmHg depending on testing protocol employed. Further optimizations of the orientation of the actuators and the ventricular chamber geometry are under research, as well as the design of a biventricular prototype to be tested within a mock-loop circulation in dynamic conditions. Although there is still a long way to develop a fully biomimetic soft artificial heart, this study clearly represents the first foundational step in this farsighted direction.
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