Research ArticleSOFT ROBOTS

Translucent soft robots driven by frameless fluid electrode dielectric elastomer actuators

See allHide authors and affiliations

Science Robotics  25 Apr 2018:
Vol. 3, Issue 17, eaat1893
DOI: 10.1126/scirobotics.aat1893
  • Fig. 1 Bioinspiration and working principle of FEDEA.

    (A) Photograph of leptocephalus (eel larva; length, about 400 mm) swimming underwater. Reprinted from Miller et al. (59), with permission from the authors. (B) Working principle of FEDEA bimorph module (not to scale): For bidirectional actuators, we make two DEAs from three layers of an acrylic elastomer adhesive. We created the active areas of the actuators by selectively passivating the surfaces of the adhesive with a powder, which allowed the conductive fluid to enter from the tubing and cover the active area. We connected the actuator to the high voltage lead of the power supply through the silicone tubing. Application of a voltage in one of the fluid chambers with respect to the external fluid induced Maxwell stress in the dielectric, inducing a bending motion away from the actuated side.

  • Fig. 2 Schematic of experimental setup and screen captures from swimming.

    Top-down (A) and side (B) view schematics of the experimental setup. The robot comprised three FEDEA bimorph modules arranged end to end. The motion of the swimmer was planarized by suspending it from a rotating boom by the tubing connected to each actuator. The boom permitted the robot to swim at a fixed depth in a large arc, reducing the impact of lateral tube tension on the robot’s performance. (C to E) Top-down view of the actuator with time indicated. Inset diagram is a top-down schematic describing which of the six DEAs are at rest (“off”) or actuated (“on”) in that frame. We cycled through the three states shown at a rate of 0.33 Hz, resulting in an average forward speed of 1.9 mm s−1. Scale bar, 5 cm.

  • Fig. 3 Demonstration of translucency.

    Photographs of the actuator over backgrounds of aquarium rocks (A) and sand (B), with dotted lines indicating the edge of the actuator. (C) Microphotograph of leptocephalus (only head shown) from the Scripps Institution of Oceanography (SIO) Marine Vertebrate Collection, illustrating the high transparency of the eel. (D) Transmission spectrum taken by hyperspectral imaging for two distinct regions in the actuator (active area, where the fluid electrodes are located, and the outside border) compared with the eel, demonstrating that the two sections of the actuator are in the range of transmittance values of the eel in the visible spectrum. Scale bars, 1 cm [(A) and (B)] and 1 mm (C).

  • Fig. 4 Fluorescence response of actuator.

    (A) Emission spectrum (excitation at 390 nm) of commercially purchased GFP embedded between two layers of VHB measured initially after injection of GFP and after 48 hours of storage in the dark at room temperature. (B and C) Photos of actuator fluorescing under UV/blue light stimulation. Scale bars, 5 cm.

Supplementary Materials

  • robotics.sciencemag.org/cgi/content/full/3/17/eaat1893/DC1

    Text S1. Swimming performance calculations.

    Text S2. Experimental measurement of thrust.

    Text S3. Longevity study.

    Fig. S1. Fabrication process for bidirectional fluid electrode DEA.

    Fig. S2. Bimorph experimental setup, images, and results.

    Fig. S3. Performance comparison of carbon grease and FEDEA bimorphs.

    Fig. S4. Photograph and schematic of experimental setup.

    Fig. S5. Comparison of experimental data and kinematic model.

    Fig. S6. Effect of actuation frequency for a bimorph FEDEA underwater.

    Fig. S7. Sound intensity results.

    Table S1. Fitting parameters for sinusoid kinematic model of the tail.

    Movie S1. Video of robot swimming under regular and UV light.

  • Supplementary Materials

    Supplementary Material for:

    Translucent soft robots driven by frameless fluid electrode dielectric elastomer actuators

    Caleb Christianson, Nathaniel N. Goldberg, Dimitri D. Deheyn, Shengqiang Cai, Michael T. Tolley*

    *Corresponding author. Email: tolley{at}ucsd.edu

    Published 25 April 2018, Sci. Robot. 3, eaat1893 (2018)
    DOI: 10.1126/scirobotics.aat1893

    This PDF file includes:

    • Text S1. Swimming performance calculations.
    • Text S2. Experimental measurement of thrust.
    • Text S3. Longevity study.
    • Fig. S1. Fabrication process for bidirectional fluid electrode DEA.
    • Fig. S2. Bimorph experimental setup, images, and results.
    • Fig. S3. Performance comparison of carbon grease and FEDEA bimorphs.
    • Fig. S4. Photograph and schematic of experimental setup.
    • Fig. S5. Comparison of experimental data and kinematic model.
    • Fig. S6. Effect of actuation frequency for a bimorph FEDEA underwater.
    • Fig. S7. Sound intensity results.
    • Table S1. Fitting parameters for sinusoid kinematic model of the tail.

    Download PDF

    Other Supplementary Material for this manuscript includes the following:

    • Movie S1 (.mp4 format). Video of robot swimming under regular and UV light.

    Files in this Data Supplement:

Navigate This Article