Research ArticleSUSTAINABLE ENERGY

A highly shape-adaptive, stretchable design based on conductive liquid for energy harvesting and self-powered biomechanical monitoring

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Science Advances  17 Jun 2016:
Vol. 2, no. 6, e1501624
DOI: 10.1126/sciadv.1501624
  • Fig. 1 Structure of the saTENG unit and its operation in single-electrode mode.

    (A) Schematic diagram showing the saTENG unit that is composed of two parts. The zoom-in illustration (top right) shows the nanostructured rubber surface. (B) Scanning electron microscopy images of the rubber surface with dry-etched nanorod structures. (C) Photograph of a typical saTENG unit with a copper wire connecting the conductive liquid. (D to F) The measured typical electrical responses of the saTENG unit working in the single-electrode mode: (D) open-circuit voltage (Voc), (E) short-circuit charge density (σsc), and (F) short-circuit current density (Jsc). (G) Schematic illustration of the operating mechanism for the single-electrode-mode saTENG. (H) Dependence of the amount of the transferred short-circuit charge (ΔQsc) on the deformation of the saTENG unit. (I) Dependence of the ΔQsc on the interval between the nylon and rubber when the deformation degree of the saTENG is the same at each operating cycle.

  • Fig. 2 Investigation of the saTENG unit working in other modes.

    (A and B) The open-circuit voltage (Voc) and short-circuit transferred charge (Qsc) of the attached-electrode contact-mode saTENG with (A) forward connection and (B) reverse connection to the liquid electrode. (C) Comparison of the ΔQsc of the saTENG working in the single-electrode mode and attached-electrode mode (contact/release motion, d1 = 5 mm). (D) Load matching test of the saTENG working in the attached-electrode contact mode at a frequency of ~3 Hz. Maximum average output power is obtained at a matched load of ~300 megohms. (E) Simulation results for the attached-electrode contact-mode saTENG exhibit the increasing electrical potential difference between the liquid electrode and the aluminum electrode as the distance between the rubber and nylon increases. Note that for simplification, the acrylic plate support under the saTENG unit is omitted in the simulation model, which will not affect the changing trend of the electrical potential due to the superposition principle of electrical potential. (F and G) Working mechanism (F) and dependence (G) of Voc and ΔQsc on the sliding displacement for the saTENG unit operating in the attached-electrode sliding mode. (H and I) Working mechanism (H) and dependence (I) of Voc and ΔQsc on the parallel-moving displacement for the saTENG unit operating in the freestanding mode.

  • Fig. 3 Influences of liquid conductivity, liquid electrode resistance, and saTENG elongation on performance.

    (A and D) The measured open-circuit voltage (Voc) (A) and the amount of short-circuit transferred charge (ΔQsc) (D) of saTENGs with electrodes of different NaCl weight concentrations. (B and E) Dependence of Voc (B) and ΔQsc (E) on the conductivity of the liquid electrode. (C and F) Dependence of Voc (C) and ΔQsc (F) on the resistance of the liquid electrode. (G) Photographs showing the saTENG under different tensile strains. Scale bar, 2 cm. (H and I) Dependence of Voc (H) and ΔQsc (I) on the tensile strain of the saTENG.

  • Fig. 4 Demonstrations of the saTENG as a wearable energy harvester and self-powered biomechanical monitor.

    (A to C) A saTENG attached to a shoe to extract energy from foot motion: (A) photograph of the pedal-like saTENG sited under the shoe; (B) equivalent electric circuit diagram depicting the order of the LED serials; and (C) photograph showing the LEDs driven by foot motion. (D to G) A saTENG looped around the arm of a subject to harvest energy from tapping motion and serve as self-powered arm motion sensor: (D) photographs showing LEDs driven by tapping the bracelet-like saTENG; (E) charging a capacitor with the brace-like saTENG; (F) the saTENG worn on the upper arm; (G) response of the saTENG to different bending angles.

  • Fig. 5 Demonstrations of the saTENG for large-area energy conversion and to harvest energy, using flowing water as the electrode.

    (A) Photograph showing the experimental arrangement for a water cushion extracting energy from mechanical motion. (B) Photograph showing that ~170 LEDs were lighted up by tapping the water cushion. (C and D) The increasing outputs with the increasing deformation of the water tube: (C) the open-circuit voltage (Voc) and (D) the amount of short-circuit transferred charge (ΔQsc). (E) Photograph showing the experimental arrangement for the saTENG harvesting mechanical energy based on household plumbing. (F) Photograph showing that ~80 LEDs were lighted up by tapping the rubber pipe with flowing water as the electrode.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/2/6/e1501624/DC1

    note S1. Detailed information for the simulation modeling.

    note S2. Factors affecting TENG’s inherent impedance.

    note S3. Consequences of the saTENG’s high inherent impedance.

    note S4. Detailed explanation for the increasing contact area with the increasing elongation of the saTENG.

    note S5. Detailed derivation of Eq. 3.

    fig. S1. The measured typical electrical responses of the saTENG unit, with paraffin oil as the electrode.

    fig. S2. Dependence of the open-circuit voltage (Voc) on the deformation of the saTENG unit and the interval between the nylon and rubber.

    fig. S3. Influence of the contact frequency of the two triboelectric surfaces on the electrical outputs of the single-electrode-mode saTENG.

    fig. S4. Influence of the length of the saTENG unit on the electrical outputs of the single-electrode-mode saTENG.

    fig. S5. Influence of the diameter of the saTENG unit on the electrical outputs of the single-electrode-mode saTENG.

    fig. S6. Theoretical results of the influence of the thickness of the rubber cover on the electrical outputs of the single-electrode-mode saTENG.

    fig. S7. Schematic diagram exhibiting the operating mechanism for the saTENG working in the attached-electrode contact mode.

    fig. S8. Simulation results showing the increasing electrical potential difference between the two electrodes for saTENG units working in the attached-electrode sliding mode and freestanding mode.

    fig. S9. Increasing conductivity of the NaCl solution with the increasing weight concentration.

    fig. S10. Experimental setup for the stretchability test.

    fig. S11. Cycle test of the saTENG under the original state.

    fig. S12. Cycle test of the saTENG under the stretched state.

    fig. S13. Equivalent circuit diagrams for the LED arrays in demonstrations.

    fig. S14. Demonstrations of the sliding-mode and freestanding-mode saTENGs to harvest energy from human motion.

    movie S1. Harvesting energy from foot motion by an outsole saTENG.

    movie S2. A bracelet-like saTENG worn on a human wrist to harvest energy from tapping motion.

    movie S3. Charging an aluminum electrolytic capacitor by a bracelet-like saTENG.

    movie S4. A bracelet-like saTENG worn on the upper arm to monitor arm motion.

    movie S5. Harvesting energy by a large-area cushion-like saTENG tapped by an acrylic plate.

    movie S6. Harvesting energy by a large-area cushion-like saTENG touched by human skin.

    movie S7. Harvesting mechanical energy based on household plumbing, using flowing water as the electrode.

    movie S8. Harvesting energy from arm swing by a saTENG working in the single-electrode sliding mode.

    movie S9. Harvesting energy from arm motion by an attached-electrode-mode saTENG.

    movie S10. Harvesting energy from moving a mouse by a freestanding-mode saTENG.

    movie S11. Harvesting energy from human walking by a freestanding-mode saTENG.

  • Supplementary Materials

    This PDF file includes:

    • note S1. Detailed information for the simulation modeling.
    • note S2. Factors affecting TENG’s inherent impedance.
    • note S3. Consequences of the saTENG’s high inherent impedance.
    • note S4. Detailed explanation for the increasing contact area with the increasing elongation of the saTENG.
    • note S5. Detailed derivation of Eq. 3.
    • fig. S1. The measured typical electrical responses of the saTENG unit, with paraffin oil as the electrode.
    • fig. S2. Dependence of the open-circuit voltage (Voc) on the deformation of the saTENG unit and the interval between the nylon and rubber.
    • fig. S3. Influence of the contact frequency of the two triboelectric surfaces on the electrical outputs of the single-electrode-mode saTENG.
    • fig. S4. Influence of the length of the saTENG unit on the electrical outputs of the single-electrode-mode
    • saTENG.
    • fig. S5. Influence of the diameter of the saTENG unit on the electrical outputs of the single-electrode-
    • mode saTENG.
    • fig. S6. Theoretical results of the influence of the thickness of the rubber cover on the electrical outputs of the single-electrode-mode saTENG.
    • fig. S7. Schematic diagram exhibiting the operating mechanism for the saTENG working in the attached-electrode contact mode.
    • fig. S8. Simulation results showing the increasing electrical potential difference between the two electrodes for saTENG units working in the attached-electrode sliding mode and freestanding mode.
    • fig. S9. Increasing conductivity of the NaCl solution with the increasing weight concentration.
    • fig. S10. Experimental setup for the stretchability test.
    • fig. S11. Cycle test of the saTENG under the original state.
    • fig. S12. Cycle test of the saTENG under the stretched state.
    • fig. S13. Equivalent circuit diagrams for the LED arrays in demonstrations.
    • fig. S14. Demonstrations of the sliding-mode and freestanding-mode saTENGs to harvest energy from human motion.
    • Legends for movies S1 to S11

    Download PDF

    Other Supplementary Material for this manuscript includes the following:

    • movie S1 (.mov format). Harvesting energy from foot motion by an outsole saTENG.
    • movie S2 (.mov format). A bracelet-like saTENG worn on a human wrist to harvest energy from tapping motion.
    • movie S3 (.mov format). Charging an aluminum electrolytic capacitor by a bracelet-like saTENG.
    • movie S4 (.mov format). A bracelet-like saTENG worn on the upper arm to monitor arm motion.
    • movie S5 (.mov format). Harvesting energy by a large-area cushion-like saTENG tapped by an acrylic plate.
    • movie S6 (.mov format). Harvesting energy by a large-area cushion-like saTENG touched by human skin.
    • movie S7 (.mov format). Harvesting mechanical energy based on household plumbing, using flowing water as the electrode.
    • movie S8 (.mov format). Harvesting energy from arm swing by a saTENG working in the single-electrode sliding mode.
    • movie S9 (.mov format). Harvesting energy from arm motion by an attached-electrode-mode saTENG.
    • movie S10 (.mov format). Harvesting energy from moving a mouse by a freestanding-mode saTENG.
    • movie S11 (.mov format). Harvesting energy from human walking by a freestanding-mode saTENG.

    Files in this Data Supplement:

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