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Manufacturing of a helical, self-coiling dielectric polymer actuator
* 1, 2 , 3 , 3 , 3 , 4
1  Technische Universität Dresden, Insitute of Solid State Electronics, 01062 Dresden, Germany
2  Technische Universität Dresden, Institute of Textile Machinery and High Performance Material Technology, 01062 Dresden, Germany
3  TU Dresden, Institut für Textilmaschinen und textile Hochleistungswerkstofftechnik
4  TU Dresden, Institut für Festkörperelektronik

https://doi.org/10.3390/IeCAT2020-08527 (registering DOI)
Abstract:

For the next generation of Soft Robotics novel materials are needed that overcome the limitations of established active materials like shape memory alloys or dielectric elastomer actuators. These new actuator types should offer fast actuation and good electromechanical coupling. In this publication, the manufacturing process and the resulting prototype of a helical dielectric polymer actuator are presented. The actuator material consists of several layers of thermoplastic elastomer and thermoplastic polymer layers with conductive fillers that are thermally bonded and stretched afterwards, which leads to self-coiling into a helical configuration. In the targeted set-up the thermoplastic dielectric layer, that is compressed by Maxwell pressure, is significantly thinner but much easier to handle than silicone films frequently used in dielectric elastomer actuators. Several manufacturing strategies are discussed and experimentally evaluated. This includes the use of different materials, their preliminary treatment, the implementation of electrically conducting layers functioning as electrodes and the contacting of the conducting layers. By identifying feasible settings and properties for these parameters, potential defects occurring during manufacturing or high-voltage activation can be minimized. By pre-stretching and then releasing a thin strip of the laminate structure, a helix is formed. The resulting prototype actuator set-up is characterized under voltages of 3 kV and shows high-speed actuation at deformation speeds of > 5 %/s. Due to the helical configuration, the observed contraction is orders of magnitude higher than the theoretical value for the corresponding flat configuration, showing the potential of the newly developed actuator material.

Keywords: artificial muscle; self-coiled actuator; dielectric polymer actuator
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