Dielectric elastomer fiber actuators can respond to external stimuli and thereby mimic natural muscles. In this work, we developed a continuous wet spinning method to prepare silicone fibers using a photocurable thiol-ene reaction. The optimized fiber exhibits seven times higher tensile strain and five times greater tensile strength compared to those of the planar film. The developed fiber actuator exhibits a large and stable linear actuation strain. The work presented herein provides a pathway for creating active soft matter with complex architectures to enable fast programmable actuation for multiple applications including artificial muscles.
Dielectric elastomer actuators (DEAs) have been proclaimed as a transformative technology with applications spanning from robotics to biomedical devices. They are especially appealing because of their key characteristics, including low weight and lifetime. However, there are still challenges in tuning these actuators for desirable mechanical performance. Here, we examine the effects of geometry and material characteristics like inner diameter and Young's modulus on the performance of hollow fiber dielectric elastomer actuators (HFDEAs). These parameters were chosen because they are amenable to experimental validation and play a straightforward, yet significant, role in DEA performance. The model's parameters are based on experimental data, giving our computational simulations a solid foundation. The study takes into consideration the electro-mechanical coupling using finite element method (FEM) simulations in COMSOL Multiphysics. While the electrodes' attraction to one another results in length expansion, the results suggest that the larger surface charge density on the internal electrode compared to the inner one in hollow fiber DEAs results in radial expansion as well. This model also provides an estimation on the actuator holding force which is challenging to evaluate experimentally. According to preliminary results, careful parameter selection can indeed increase the holding force, thereby enhancing the actuator's overall effectiveness. In conclusion, this study provides an understanding of design parameters of HFDEA offering a comprehensive framework for HFDEA design by integrating both experimental and computational approaches.
Fiber dielectric elastomer actuators (DEAs) are potential candidates for the realization of artificial muscles owing to, amongst others, their linear actuation principle. In this work, a polydimethylsiloxane (PDMS) hollow fiber is prepared through a spinning method using the photocurable thiol-ene reaction between a thiol (R-SH) group and a double bond (C=C). The developed PDMS hollow fiber has an external diameter of 463 μm and uniform wall thickness of 78 μm, and presents tensile properties of ~600 % strain at break and 0.22 MPa strength, compared to these of the planar film of 86 % strain at break and 0.14 MPa tensile strength. Fiber DEAs are prepared by using ionic liquid as an inner electrode and ionogel as an electrical outer sheath. Due to the highly transparent PDMS elastomer layer and ionic liquid-based electrodes, the fiber DEA presents a transparency of ~91 % in a visible light spectrum. The fiber DEA exhibits a large linear strain of 9 % at 50 V/μm. Furthermore, the fiber DEA can be assembled into bundles for increased forces. The work presented herein provides a pathway for creating active soft matter with complex architectures to enable fast programmable actuation for multiple applications including invisible robots.
Dielectric elastomers (DEs) have shown a significant potential for actuation applications such as artificial muscles, due to their low weight, fast response, silent operation, and high efficiency. DEs with large actuation strain or low driving voltages are usually incorporated with high permittivity fillers. Ionic liquid (IL) presents a promising improvement on relative permittivity of DEs, however, its aggregation in the elastomer matrix by the physical blending modification has limited the improvement on actuating performances. In this study, a new strategy is developed to prepare high-performance PDMS elastomers by the formation of bis(1-ethylene-imidazole-3-ium) bromide between the PDMS backbones, after which the actuation performance of the IL-modified elastomer is investigated.
Dielectric elastomers (DEs) can undergo very large spatial deformations in response to an externally applied electrical field, giving them significant potential as soft actuators. High-performance DEs are usually modified by high-permittivity additives, which are used to lower driving voltages. In this study, a novel high-permittivity soft additive (LMS-EIL) was developed via the combination of high-permittivity ionic liquid (IL) and chloropropyl-silicone, enabling good compatibility with the silicone matrix. The relative dielectric permittivity of the novel silicone oil additive was 9×104 times higher at 0.1Hz compared to pristine chloropropyl-silicone oil. High-permittivity silicone elastomers were then achieved via incorporation of this novel IL-grafted chloropropyl-silicone oil. The relative dielectric permittivity of elastomers modified with 10 parts per hundred rubber (phr) LMS-EIL increased from 3.0 (pure film) to 22 at 0.1Hz, while the Young’s modulus decreased steadily with increasing LMS-EIL concentration. A simplified figure of merit (Fom') was used to evaluate actuation performance, and was shown to be 8.1 for the elastomer incorporated with 10 phr LMS-EIL, indicating excellent potential for use as an actuator.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.