Electrical and Mechanical Self‐Healing in High‐Performance Dielectric Elastomer Actuator Materials

Zhang, Yan; Ellingford, Christopher; Zhang, Runan; Roscow, James; Hopkins, Margaret; Keogh, Patrick; McNally, Tony; Bowen, Christopher R.; Wan, Chaoying

doi:10.1002/adfm.201808431

Cited by 106 publications

(118 citation statements)

References 49 publications

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“…After self‐reparation, only a very small decrease in actuation performance was noted. Self‐reparation of actuators has been reported before and it was either due to electrode material which degraded at the breakdown site or due to flowing of plasticizer into defects . In this case, the self‐reparation of the actuators is due to combustion of the conductive path.…”

Section: The Amount Of Reagents Used For the Synthesis Of Thin Filmsmentioning

confidence: 91%

“…Self-reparation of actuators has been reported before and it was either due to electrode material which degraded at the breakdown site or due to flowing of plasticizer into defects. [38][39][40][41] In this case, the self-reparation of the actuators is due to combustion of the conductive path. During electrical breakdown, the small spark produced burns part of the electrode and thus insulates the conductive path.…”

Section: Wwwadvancedsciencenewscommentioning

confidence: 99%

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Artificial Muscles: Dielectric Elastomers Responsive to Low Voltages

Sheima

Caspari

Opris

2019

Macromol. Rapid Commun.

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The lack of soft high‐dielectric‐permittivity elastomers responsive to a low voltage has been a long‐standing obstacle for the industrialization of dielectric elastomer actuators (DEA) technology. Here, elastomers that not only possess a high dielectric permittivity of 18 and good elastic and insulating properties but are also processable in very thin films by conventional techniques are reported. Additionally, the elastic modulus can be easily tuned. A soft elastomer with a storage modulus of E = 350 kPa, a tanδ = 0.007 at 0.05 Hz, and a lateral actuation strain of 13% at 13 V µm−1 is prepared. A stable lateral actuation over 50 000 cycles at 10 Hz is demonstrated. A stiffer elastomer with an E = 790 kPa, a tanδ = 0.0018 at 0.05 Hz, a large out‐of‐plane actuation at 41 V µm−1, and breakdown fields of almost 100 V µm−1 is also developed. Such breakdown fields are the highest ever reported for a high‐permittivity elastomer. Additionally, actuators operable at a voltage as low as 200 V are also demonstrated. Because the materials used are cheap and easily available, and the chemical reactions leading to them allow upscaling, they have the potential to advance the DEA technology.

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Section: The Amount Of Reagents Used For the Synthesis Of Thin Filmsmentioning

confidence: 91%

Section: Wwwadvancedsciencenewscommentioning

confidence: 99%

Artificial Muscles: Dielectric Elastomers Responsive to Low Voltages

Sheima

Caspari

Opris

2019

Macromol. Rapid Commun.

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“…Yet prestrained DEAs provide contractile strains in only a small proportion of the total device area . Moreover, these devices often exhibit impaired cycling and breakdown behavior and the presence of a rigid frame limits the geometries that can be achieved . Recent attention has been directed toward developing approaches that enable contractile displacements in prestrain‐free DEAs, including manual and automated stacking of individual planar layers or sequential deposition of active materials via inkjet printing and spray coating .…”

Section: Introductionmentioning

confidence: 99%

3D Printing of Interdigitated Dielectric Elastomer Actuators

Chortos

Hajiesmaili

Morales

et al. 2019

Adv Funct Materials

147

128

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Dielectric elastomer actuators (DEAs) are soft electromechanical devices that exhibit large energy densities and fast actuation rates. They are typically produced by planar methods and, thus, expand in-plane when actuated. Here, reported is a method for fabricating 3D interdigitated DEAs that exhibit in-plane contractile actuation modes. First, a conductive elastomer ink is created with the desired rheology needed for printing high-fidelity, interdigitated electrodes. Upon curing, the electrodes are then encapsulated in a self-healing dielectric matrix composed of a plasticized, chemically crosslinked polyurethane acrylate. 3D DEA devices are fabricated with tunable mechanical properties that exhibit breakdown fields of 25 V µm −1 and actuation strains of up to 9%. As exemplars, printed are prestrainfree rotational actuators and multi-voxel DEAs with orthogonal actuation directions in large-area, out-of-plane motifs.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adfm.201907375.cycling and breakdown behavior [33][34][35] and the presence of a rigid frame limits the geometries that can be achieved. [24,36] Recent attention has been directed toward developing approaches that enable contractile displacements in prestrain-free DEAs, including manual and automated stacking of individual planar layers [37] or sequential deposition of active materials via inkjet printing [38] and spray coating. [39] The fabrication of contractile actuators with vertically oriented electrodes offers a more promising approach (Figure 1b). While arrays of vertical electrodes can be patterned lithographically, new masks must be generated for each device design. [40][41][42] By contrast, 3D printing enables the rapid design and fabrication of soft materials in nearly arbitrary geometries. [43][44][45][46][47] For example, direct ink writing (DIW), an extrusion-based 3D printing method, has been used to pattern soft functional materials, including sensors, [48] stretchable electronics, [49] liquid crystalline elastomers, [50] and soft robots. [51,52] While this method has recently been used to print DEAs, they do not exhibit an in-plane contractile response. [52][53][54] Here, we create 3D DEAs composed of interdigitated vertical electrodes that are printed, cured, and encapsulated in an insulating dielectric matrix (Figure 1c). These prestrain-free contractile DEAs can be produced in nearly arbitrary geometries. During their actuation, the stress generated is given by σ = ε 0 ε r (E) 2 , where ε 0 is the vacuum permittivity, ε r is the dielectric constant, and E is the electric field. For small strains, the actuation strain (s z ) is s z = σ/E Y = ε 0 ε r (E) 2 /E Y , where E Y is the Young's modulus. Their actuation performance is therefore maximized by increasing the breakdown field and dielectric constant, while simultaneously reducing the elastic modulus of the matrix. Since variations in the dielectric thickness can cause localization of the electric field that results in p...

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“…A feature of DEs is that they can not only convert electrical into mechanical energy actuators (DEAs) but also transduce mechanical into electrical energy generators (DEGs) [6]. In the future, DEs are to be used reliably in applications that include soft robotics, medical devices, artificial muscles, and electronic skins [7].…”

Section: Dielectric Elastomersmentioning

confidence: 99%

Introductory Chapter: The Way to Fulfill Science Fiction

Dong¹

2019

Smart and Functional Soft Materials

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Electrical and Mechanical Self‐Healing in High‐Performance Dielectric Elastomer Actuator Materials

Cited by 106 publications

References 49 publications

Artificial Muscles: Dielectric Elastomers Responsive to Low Voltages

Artificial Muscles: Dielectric Elastomers Responsive to Low Voltages

3D Printing of Interdigitated Dielectric Elastomer Actuators

Introductory Chapter: The Way to Fulfill Science Fiction

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