Dielectric elastomer actuators (DEAs) have raised interest due to their remarkable capabilities in various applications, such as soft robotics, haptic feedback systems, and biomedical devices. To harness the full potential of DEAs, the choice of the electrode material and fabrication method is critical. This study investigates the application of carbon based printed electrodes for DEAs, focusing on three prominent printing techniques: pad printing, inkjet printing and stencil printing. Comparisons are made to evaluate their performance in terms of electrical conductivity, mechanical properties and actuator performance. Findings from this research aim at providing valuable insights into selecting the most suitable electrode fabrication method for specific DEA applications.
Dielectric Elastomer Actuators (DEAs) are a type of smart material described as compliant capacitors. They show impressive performances as soft actuators, such as a high strain and fast response. Nonetheless, replicating natural muscle function with DEAs has posed a challenge since DEAs exhibit in-plane expansion, whereas natural muscles contract when stimulated. This publication aims to investigate the use of a normal configuration of DEAs to obtain a contractile movement for post paralysis facial reanimation, by inversing its actuation cycle: the voltage applied on the DEA will constantly be on to keep the DEA stretched and will be off when a contraction movement is wanted, for instance for smiling. Several difficulties linked to this solution need to be considered, such as the self-discharge rate of the DEA, linked to the leakage current flowing through the dielectric when a voltage is applied. The leakage current corresponds to a leakage of charge between the two electrodes and is suggested to influence the self-discharge rate but also the dielectric breakdown and the performance of the actuator. As DEAs present a fast self-discharging rate, the charging frequency of DEAs should be determined to avoid unwanted displacement leading to visible facial spasms. DEAs and their self-discharge rate are characterized, to determine the chosen charging frequency and duty cycle for facial reanimation. The goal is to have the minimum discharge between two actuation cycles. A discharge model was proposed and validated experimentally, allowing to determine a chosen frequency of 2 Hz and 50% duty cycle, leading to a discharge of less than 3% between two actuation cycles, and thus allows to consume 1.5% less energy over each cycle compared to a continuous actuation.
Dielectric Elastomer Actuators (DEAs) have emerged as versatile and promising devices for a multitude of applications, including soft robotics, haptic interfaces, and artificial muscles. DEAs are an interesting soft actuator technology due to their high energy density, and fast response. They can be described as compliant capacitors composed of a dielectric elastomer film situated between two electrodes. When a voltage is applied, it induces a compressive Maxwell stress, causing a reduction in thickness and thus an expansion in the other dimensions. However, DEAs tend to exhibit limited deformations under uni-axial forces. To overcome this limitation and induce substantial uni-axial deformations, it is suggested that DEAs should be constrained in the other directions. This constraint can be realized by reinforcing the DEA with unidirectional fibers, resulting in strains up to 75% higher for reinforced DEAs than for conventional DEAs. In this paper, the response time of uniaxial fiber-reinforced DEAs is studied, to evaluate the influence of the reinforcement on the frequency response. To that end, uni-axial fiber reinforced DEAs with a silicone dielectric layer are fabricated by embedding 3D printed fibers of different materials onto the actuators. Fused deposition modelling is used by tuning the infill of the printed part, allowing a fast, simple, and accessible fabrication of the fibers. The response time of the actuators is improved with the use of uni-axial fiber reinforced DEAs, as they provide a more rigid structure and less losses, with a decrease of up to 15% in the response time.
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