Printing Reconfigurable Bundles
of Dielectric Elastomer Fibers

(a) Schematic view of multi-material, multicore-shell 3D printing, including nozzle-based printhead and co-axial dielectric elastomer fiber (DEF), vertical coils, and bundles. [Optical images of the fiber cross-section highlight its multi-material, multicore-shell geometry.] (b) Side view of the cyclic rotation of this steerable DEF bundle. (c) Steerable DEF bundles imaged from below, showing the end of a 3x3 DEF bundle bending in 8 different directions in response to the different addressable actuations shown. The nine circles represent individual fibers and the ones colored red represent those being actuated in each frame. The voltage is 7 kV. The center of each frame is the fixed end of the bundle.

A team at the Harvard MRSEC led by Clarke and Lewis has developed a multi-core-shell 3D printing method for fabricating dielectric elastomer fibers, coils, and bundles that exhibit programmed actuation. First, conductive and dielectric matrix inks were produced with the requisite rheological, electrical, and mechanical properties for printing of dielectric elastomer fibers (DEFs). Next, an analytical model was developed to predict the deformation of individual DEFs. Inspired by human muscles, the team generated reconfigurable DEF bundles using this approach, in which each fiber is individually addressable. These DEF bundles could be steered in eight different directions by exploiting this feature. This platform opens new avenues for the integrated design and fabrication of programmable soft matter in three dimensions.

Publication:
A. Chortos, J. Mao, J. Mueller, E. Hajiesmaili, J.A. Lewis, and D.R. Clarke, "Printing Reconfigurable Bundles of Dielectric Elastomer Fibers", Advanced Functional Materials 2010643 (2021)

David R. Clarke (Material Science & Mechanical Engineering), and
Jennifer A. Lewis (Material Science & Bioengineering)
2020-2021 Harvard MRSEC (DMR-2011754)