Design and modelling of a tubular dielectric elastomer actuator with constrained radial displacement as a cardiac assist device

Abstract

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.

A novel soft cardiac assist device based on a dielectric elastomer augmented aorta: An in vivo study

“…The small step at this end of the connector ensured the sealing of the anastomosis. The external housing limited the radial expansion of the DEA to avoid electromechanical instability that could lead to early breakdown of the actuator 18 . Figure 1d shows the overall dimensions of the device.…”

“…In both cases, with the selected designs and the blood pressure levels, the DEA requires very high‐voltage levels (>6 kV) to obtain significant deformation. During the in vivo experiments, the actuation voltage was selected as trade‐off between maximum deformation and electric breakdown limit of the device 18 . The first activation level for the measurements started at 6 kV, and it was then increased to 6.5 and 7 kV if the DEA did not break before.…”

“…During the in vivo experiments, the actuation voltage was selected as trade-off between maximum deformation and electric breakdown limit of the device. 18 The first activation level for the measurements started at 6 kV, and it was then increased to 6.5 and 7 kV if the DEA did not break before.…”

Highly anisotropic carbon fiber electrodes for DEAs and their dynamic non-monotonic conductive properties

“…4 This approach has recently garnered significant attention in the electroactive polymer community. 5 Various materials mentioned in the literature, such as nylon and carbon fibers, can be integrated either as individual fibers or in textile form. 4,[6][7][8] As demonstrated by Endesfelder et al, 9 introducing anisotropy can increase the force output by more than double depending on the pre-stretch level.…”

Development of a novel parallel soft manipulator with sensing capabilities

“…Currently, there are three major soft manipulator/robot research avenues [4]: (a) the research on the manipulator propelled by hydropneumatic/hydrodynamic or flexible rope, such as the FESTO Company's elephant trunk manipulator, has been underway for a substantial length of time, and many relevant theories are developed [5]; (b) by ultra soft silicone material as a structural material, and the use of 3D printing an integrated soft arm, such as octopus tentacles soft arm [6], that kind of soft arm is mostly gas driven, under the condition of relatively low air pressure it can produce large deformation and flexible attitude, it is the most popular research direction in a number of countries and institutions; (c) use a novel intelligent soft material, such as dielectric elastomer [7,8], shape memory alloy [9] and conductive polymer (electro active polymer) [10], among others, as a driving force; deformation occurs under the control of changing external fields; and this design is widely used in micro robots, which is a branch of mechanical engineering that applies material science.…”