Research ArticleAPPLIED SCIENCES AND ENGINEERING

Fast-moving soft electronic fish

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Science Advances  05 Apr 2017:
Vol. 3, no. 4, e1602045
DOI: 10.1126/sciadv.1602045
  • Fig. 1 Fabrication of electro-ionic fish.

    (A) Muscle laminate fabrication: A thin hydrogel film electrode was sandwiched between two biaxially prestretched (3 × 3) DE membranes (VHB membrane; initial thickness, 1.5 mm); the assembly was then fixed within ABS frames. (B) Fin fabrication: Two silicone films (thickness, 0.5 mm) and two rigid “L”-shaped acrylic frames (thickness, 1 mm) were glued together to form two pectoral fins, which were placed between two ABS frames. (C) The fin and muscle laminates were stacked together. The white and brown dashed lines indicate the locations of encapsulated hydrogel and feed line by DE membranes. (D) Liquid silicone precursor was poured into the mold (ABS frames) to fabricate the soft body. (E) The soft body bends after demolding. (F) Installation of the silicone tail and electromagnets.

  • Fig. 2 Operation mechanism of electro-ionic fish.

    Front view of the actuating mechanisms. (A) In water, the soft body (silicone body) and the muscle laminates (two DE membranes and one hydrogel film) are deformed by the shrinking of the prestretched DE membranes with a bending curvature. (B) When a high voltage (HV) is applied to the muscle laminates, the electric field drives the ions in both the surrounding water and the hydrogel. Positive and negative charges accumulate on both sides of the DE membranes, inducing Maxwell stress and relaxing the DE membranes. The bending of the electro-ionic fish decreases. The surrounding water functions as the electric ground. (C) Front view (FEA) of the robotic fish in the rest state with a large bending angle θ1. (D) Front view (FEA) for the actuated state of the robotic fish with a small bending angle θ2. (E) Tilted view of FEA simulation for the rest state of the robotic fish. (F) Tilted view of FEA simulation for the actuated state of the robotic fish. Red dashed curves indicate the variation of bending. (G) Snapshot (similar tilted view) of a swimming manta ray. The body and fins of the manta ray buckle down with a large bending angle and (H) a small bending angle.

  • Fig. 3 Live snapshots of the swimming fish with wired power.

    t = 0 is defined as the beginning of the cycle with the fin in the actuated state, and T represents the time required for one full flapping cycle. (A) Bending variations of the soft body and fins (front views). (B) Forward motion of the fish and undulatory motion of the fins (side views; the white dashed lines highlight the fin edges). (C) The top views correspond to (B).

  • Fig. 4 Quantitative performance evaluation via wired power.

    (A) Voltage signal from the signal generator is amplified through a high-voltage amplifier and fed to the soft robotic fish. (B) The speed of robotic fish demonstrates a double peak distribution and reaches a maximum of 13.5 cm/s.

  • Fig. 5 Performance of the untethered fish.

    (A) Tilted view of the fish showing the onboard system for power and remote control. (B) Live snapshots of the swimming of the robotic fish under remote control (voltage of 8 kV and 5 Hz).

  • Fig. 6 The thermal tolerance and visual disguise of the fish.

    The soft robotic fish can swim in a wide range of water temperatures from (A) 0.4°C to (B) 74.2°C. The stealth sailing of the fish with (C) wired power and (D) onboard power.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/4/e1602045/DC1

    section S1. Prestretching of DE membranes

    section S2. Hydrogel and muscle laminate

    section S3. The fin laminate, soft body, and steering tail

    section S4. Preliminary attempt to fabricate a soft fish by 3D printing

    section S5. Measurements of speed, turning radius, and thrust

    section S6. The onboard power and control system (Epod)

    section S7. Von Mises stress contours in FEA simulation

    section S8. Water conductivity

    section S9. Viscous effect of the DE membranes

    fig. S1. The prestretch of the DE membrane.

    fig. S2. Fabrication of the muscle laminate.

    fig. S3. Fabrication of the fin laminate.

    fig. S4. Fabrication of the soft body and steering tail.

    fig. S5. Buoys and electromagnetic steering tail.

    fig. S6. Soft fish by 3D printing.

    fig. S7. Von Measurement of the speed and turning radius.

    fig. S8. The Epod.

    fig. S9. Von Mises stress distribution by FEA.

    table S1. Speed and turning radius.

    table S2. Capacitance, thrust, power, and efficiency.

    table S3. Dimensions and weight of the soft robot fish.

    movie S1. The swimming of the tethered powered fish.

    movie S2. The flapping and undulatory motions of the fins of an anchored wired fish at various frequencies (1, 3, and 4 Hz).

    movie S3. The swimming and turning of an untethered fish with and without a payload (a video camera).

    movie S4. Video record captured by an onboard camera on a swimming fish.

    movie S5. The swimming of a transparent tethered fish in cold (0.4°C) and hot (74.2°C) water.

    movie S6. The swimming of a transparent tethered fish and partially 3D-printed fish.

  • Supplementary Materials

    This PDF file includes:

    • section S1. Prestretching of DE membranes.
    • section S2. Hydrogel and muscle laminate.
    • section S3. The fin laminate, soft body, and steering tail.
    • section S4. Preliminary attempt to fabricate a soft fish by 3D printing.
    • section S5. Measurements of speed, turning radius, and thrust.
    • section S6. The onboard power and control system (Epod).
    • section S7. Von Mises stress contours in FEA simulation.
    • section S8. Water conductivity.
    • section S9. Viscous effect of the DE membranes.
    • fig. S1. The prestretch of the DE membrane.
    • fig. S2. Fabrication of the muscle laminate.
    • fig. S3. Fabrication of the fin laminate.
    • fig. S4. Fabrication of the soft body and steering tail.
    • fig. S5. Buoys and electromagnetic steering tail.
    • fig. S6. Soft fish by 3D printing.
    • fig. S7. Measurement of the speed and turning radius.
    • fig. S8. The Epod.
    • fig. S9. Von Mises stress distribution by FEA.
    • table S1. Speed and turning radius.
    • table S2. Capacitance, thrust, power, and efficiency.
    • table S3. Dimensions and weight of the soft robot fish.
    • Legends for movies S1 to S6

    Download PDF

    Other Supplementary Material for this manuscript includes the following:

    • movie S1 (.mp4 format). The swimming of the tethered powered fish.
    • movie S2 (.mp4 format). The flapping and undulatory motions of the fins of an anchored wired fish at various frequencies (1, 3, and 4 Hz).
    • movie S3 (.mp4 format). The swimming and turning of an untethered fish with and without a payload (a video camera).
    • movie S4 (.mp4 format). Video record captured by an onboard camera on a swimming fish.
    • movie S5 (.mp4 format). The swimming of a transparent tethered fish in cold (0.4°C) and hot (74.2°C) water.
    • movie S6 (.mp4 format). The swimming of a transparent tethered fish and partially 3D-printed fish.

    Files in this Data Supplement: