Although heart transplantation is a gold standard for severe heart failure, there is a need for alternative effective therapies. A dielectric‐elastomer aorta is used to augment the physiological role of the aorta in the human circulatory system. To this end, the authors developed a tubular dielectric elastomer actuator (DEA) able to assist the heart by easing the deformation of the aorta in the systole and by increasing its recoil force in the diastole. In vitro experiments using a pulsatile flow‐loop, replicating human physiological flow and pressure conditions, show a reduction of 5.5% (47 mJ per cycle) of the heart energy with this device. Here, the controlled stiffness of the DEA graft, which is usually difficult to exploit for actuators, is perfectly matching the assistance principle. At the same time, the physiological aortic pressure is exploited to offer a prestretch to the DEA which otherwise would require an additional bulky pre‐stretching system to reach high performances.

Commercial dielectric elastomers and their modification methods are reviewed. A method is proposed to overcome the complex interdependency of their properties allowing quick comparison and selection of suitable materials for soft actuator applications.

Performance of dielectric elastomer actuators is closely related to its breakdown field. On the other hand, to enhance the available energy, multilayer configuration is needed to increase the amount of active material. However, multilayer configuration suffers from a drastic reduction of the affordable electric field related to field concentration at edges. After showing how the conductivity of the air helps to smooth the field in a single layer configuration, this effect has been mimicked in the multilayer by adding carbon particles in a thin silicone layer around the electrode. A change in the electric properties around the edges reduces the local concentration of the electric field and allows a significant improvement of the voltage breakdown in the multilayer structure. Therefore, the performance of multilayer has been considerably enhanced.

Although heart transplant is the preferred solution for patients suffering from heart failures, cardiac assist devices remain key substitute therapies. Among them, aortic augmentation using dielectric elastomer actuators (DEAs) might be an alternative technological application for the future. The electrically driven actuator does not require bulky pneumatic elements (such as conventional intra-aortic balloon pumps) and conforms tightly to the aorta thanks to the manufacturing method presented here. In this study, the proposed DEA-based device replaces a section of the aorta and acts as a counterpulsation device. The feasibility and validation of in vivo implantation of the device into the descending aorta in a porcine model, and the level of support provided to the heart are investigated. Additionally, the influence of the activation profile and delay compared to the start of systole is studied. We demonstrate that an activation of the DEA just before the start of systole (30 ms at 100 bpm) and deactivation just after the start of diastole (0-30 ms) leads to an optimal assistance of the heart with a maximum energy provided by the DEA. The end-diastolic and left ventricular pressures were lowered by up to 5% and 1%, respectively, compared to baseline. The early diastolic pressure was augmented in average by up to 2%.

In this paper, we propose an improvement of a dielectric elastomer actuator (DEA) based augmented aorta. The actuator is a multi-layered tubular DEA subject to the internal pressure of the blood. When activated in synchronisation with the heart, the DEA supplies energy and limits the load on the left ventricle. The improvement consists in implementing a constraint on the radial displacement of the actuator. This addition allows to increase the electromechanical stability of the device by avoiding snap-through of the material leading to irreversible breakdown. By increasing the stability of the device, it allows to reach higher activation voltages and thus, a higher energy. In order to help the design of this new actuator, we have developed an analytical model of the inflation of a tubular DEA. In addition to previous works, the new model takes into account the multi-layered structure of the device as well as the constraint on the radial displacement to obtain accurate characteristics of the DEA. After validation with specially design experiments, the modelling is used to study the influence of the radial limitation value on the performances of the DEA.