The development of a fully engineered artificial heart capable of replicating natural cardiac function remains a critical clinical and engineering challenge. Current artificial heart prototypes are still far from replicating key physiological characteristics such as native tissue mechanics, pressure-volume dynamics, and patient-specific customization. This seminar will present recent fundamental science and manufacturing developments to: (i) develop and study the mechanics of twisted and coiled polymer actuators (TCPAs), (ii) construct an actuator-driven and phase-dependent lumped parameter model to predict the performance of TCPA-driven ventricles, and (iii) fabricate a passive heart structure that mimics myocardial fiber-reinforced anisotropy using embedded 3D printing.

While prior studies on soft actuators have mainly focused on load-lifting capabilities under isobaric conditions, natural cardiac cycles involve complex behaviors including isovolumetric contraction and relaxation phases. We investigated the isometric behavior of TCPAs to better replicate these physiological processes, characterizing their passive, active, and total force components. Furthermore, we developed a design analysis model which links the mechanics of pumping to the requirements of a soft actuator within a full beating cycle to capture its dynamic behavior. By coupling this with a Windkessel model, we enable the replication of the heart’s pressure-volume loop through a force-strain analogy.

A major challenge in cardiac modeling lies in replicating the varying myocardial fiber architecture, which is essential for inducing the apical torsion responsible for high ejection fractions. We address this gap through the use of embedded 3D printing, which enables the precise deposition of reinforcing fibers within a soft matrix in a spatially varying manner. To achieve this, we investigated the rheological characteristics of the gel medium, the elastomer serving as the soft matrix of the artificial heart, and the SEBS/toluene ink serving as reinforcing fibers. Subsequently, we developed a custom polar 3D printer with a pneumatic and volumetric control dispensing system that enables printing along inclined planes. Building on this platform, we generated a printability map for silicone elastomers based on fiber geometries under varying printing conditions to ensure robust interlayer fusion. Finally, we embedded SEBS fibers with different spacings, successfully demonstrating the resulting structural anisotropy.