Polymère électroactif

vignette|Figure 1 : The black strips are the working electroactif polymers. They are powered with the same squared voltage. 300px|vignette|Figure 2 : illustration d'une pince en EAP. (a) Une tension est appliquée, les deux doigts en EAP se déforment de sorte à contourner la balle. (b) Lorsque la tension électrique est coupée, les doigts en EAP reprennent leur forme d'origine et attrapent la balle. (c). Les polymères électroactifs (PEA) ( (EAP)), sont des polymères dont la forme ou la taille changent lorsqu'ils sont stimulés par un champ électrique. L'utilisation principale de ce type de matériau est la fabrication d'actionneurs et de capteurs. Une propriété intéressante des EAP est qu'ils sont capables de grandes déformations, ainsi que de forces importantes. La plus grande partie des actionneurs actuels est fabriquée à partir de céramiques piézo-électriques. Ces matériaux sont certes capables de produire des forces très élevées, cependant leur domaine de déformation n'excède pas quelq

High Permittivity Silicones for Dielectric Elastomer Actuators

Simon Johannes Dünki

Many technical advances of modern society sprout from the creation of specially customized polymer materials exhibiting unique combinations of properties uncharted so far. Amid this plurality of highly versatile materials, the class of electroactive polymers (EAPs) bears the special ability to undergo large shape changes when exposed to electrical stimulation. Such materials offer new perspectives in automation, robotics and medicine. Especially the dielectric elastomer actuators (DEA) technology is considered as highly promising among EAPs due to the simple working principle and actuation characteristics similar to mammalian muscles. Despite great research efforts and remarkable progress in regard to materials and devices, the commercial breakthrough of the DEA technology is still outstanding. A major obstacle for their application is the high driving voltage needed to obtain a reasonable actuation. The development of tailored elastomers that overcome this deficiency is therefore a main research focus in academia and industry. The exceptional elastic and dielectric characteristics of silicones nominate them as an ideal vantage point to start this endeavor. Their low permittivity inherently decreases the actuation performance and should therefore be optimized with all other properties remaining unaffected. In the present work, dipoles were covalently attached to a siloxane backbone in order to increase the permittivity thereof and achieve a material with an enhanced actuation performance at low driving voltages for DEAs. The introduction of the polar groups to the polymer side chains was carried out via thiol-ene chemistry, which enabled a quantitative functionalization of the polymer backbone. Three different polar groups, nitrile, thioether and sulfones, were investigated and the corresponding functionalized polysiloxanes were prepared and characterized. Thorough dielectric, mechanical and electromechanical investigations were conducted on polysiloxane based elastomers with different content of nitrile groups. In addition, first results were obtained with thioethers and sulfones which are also promising candidates to enhance the permittivity of polysiloxanes. Most of the synthesized polysiloxanes show glass transition temperatures well below room temperature, an important prerequisite to ensure elastic properties. Polysiloxanes that carry a butylthioether moiety at every repeat unit doubled the permittivity of the elastomer. With the same amount of the nitrile or sulfone dipoles, a six respectively eight times higher permittivity as compared to regular siloxane is achieved. However, with enhanced dipole content also an increase of the electrical conductivity of the polymer was observed. A simple one-step process to prepare cross-linked polar silicone films was developed using UV light triggered thiol-ene addition. A strong correlation between the dipole content in the material and the resulting actuation strain was found. Finally, a polar silicone elastomer was prepared that showed up to 20.5% lateral strain under a field as low as 10.8 V/um. Compared to commercial silicone this corresponds to an effective voltage reduction by about 70%. Processing such materials in films the thickness of which is below 10 um would result in an actuator that can be driven below 100 V.

EPFL2017

Wireless Electrohydrodynamic Actuators for Propulsion and Positioning of Miniaturized Floating Robots

Vito Cacucciolo, Yu Kuwajima

Autonomous soft robots require compact actuators generating large strokes and high forces. Electro-fluidic actuators are especially promising, they combine the advantages of electroactive polymers (low-power consumption, fast response, and electrical powering) with the versatility of fluidic systems (force/stroke amplification). EHD (electrohydrodynamic) actuators are electro-fluidic actuators whose motion results from charges being induced and accelerated in a liquid. They are extremely compact, silent, and low power (

WILEY2021

High Permittivity Silicones for Dielectric Elastomer Actuators

Simon Johannes Dünki

EPFL2017

High Permittivity Silicones for Dielectric Elastomer Actuators

Wireless Electrohydrodynamic Actuators for Propulsion and Positioning of Miniaturized Floating Robots

Editorial: Soft Robotics Based on Electroactive Polymers

High Permittivity Silicones for Dielectric Elastomer Actuators

Wireless Electrohydrodynamic Actuators for Propulsion and Positioning of Miniaturized Floating Robots

Editorial: Soft Robotics Based on Electroactive Polymers