Transparent PDMS fiber actuator with ionic liquid-based electrodes

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.