Research ArticleMATERIALS SCIENCE

Rehealable, fully recyclable, and malleable electronic skin enabled by dynamic covalent thermoset nanocomposite

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Science Advances  09 Feb 2018:
Vol. 4, no. 2, eaaq0508
DOI: 10.1126/sciadv.aaq0508
  • Fig. 1 Rehealable, fully recyclable, and malleable e-skin.

    (A) Schematic illustration of rehealability and full recyclability of the e-skin. (B) The malleable e-skin can be conformally mounted onto a human arm (left). When mechanically cut broken (middle), the e-skin can be rehealed by applying a small amount of rehealing agent and heat pressing (right). (C) The e-skin can be fully recycled using the recycling solution (left), yielding the solution with dissolved oligomers/monomers and AgNPs at the bottom (middle). The solution and AgNPs can be reused to make a new e-skin (right).

  • Fig. 2 Rehealing and characterization of the pure and conductive polyimine films.

    (A) Polymerization of the polyimine. (B) Schematic illustration of the rehealing process. Optical images of the polyimine film are shown at the bottom of each frame. (C) Optical microscopy images of a pure polyimine film that is cut broken (top) and rehealed (bottom). After rehealing, the cut is invisible (middle and bottom). (D) Optical microscopy images of a conductive polyimine film that is cut broken (top) and rehealed (bottom). After rehealing, the cut is invisible (middle), but traces of the cut can still be seen under microscope (bottom). (E) SEM images of the cross sections of a conductive polyimine film before (top) and after (middle) rehealing. The magnified view at the bottom shows the dispersion of AgNPs in the polymer network. Uniaxial tension test results of pure (F) and conductive (G) polyimine films before and after rehealing. Three samples were tested for each case. (H) Electrical resistivity measurements of the conductive polyimine films with different AgNP weight ratios before and after rehealing.

  • Fig. 3 Recycling and characterization of the pure and conductive polyimine films.

    (A) Schematic illustration of the recycling process. (B) The LED light is on when a conductive polyimine film is connected into a simple lighting circuit (top left). After recycling, the LED light turns off (top right). The recycled solution is then cast into a new, square petri dish (bottom right). After polymerization, the film is conductive and the LED light turns on (bottom left). Uniaxial tension test results of the pure (C) and conductive (D) polyimine films before and after recycling. (E) Electrical resistivity measurements of the conductive polyimine films before and after recycling.

  • Fig. 4 Characterization of the rehealable, fully recyclable, and malleable e-skin.

    (A) Schematic illustration of the design of the e-skin (top). An optical image of the e-skin is shown at the bottom. (B) Characterization of the tactile sensor. When two different balance weights (2 and 5 g) are put on the top of the tactile sensor array (top left), both the weights and positions are detected (top right). The relative capacitance change of the tactile sensor versus weight shows a linear relationship (bottom left). Repeatability of the tactile sensor is tested for 100 cycles with a 13.2-g weight (bottom right). Characterization of the flow sensor with different currents (C), temperature sensor (D), and humidity sensor (E). The sensing performance of the flow sensor (F), humidity sensor (G), and tactile sensor (H) on an integrated e-skin in a complicated environment. Stages 1, 2, and 3 are corresponding to applying air flow, moisture, and screw nuts on the e-skin. (I) Comparison of sensing properties of the flow sensor before and after rehealing. (J) Comparison of sensing properties of the tactile sensor before and after recycling. (K) Malleability enables the e-skin to change its shape between flat (left) and curved (right) states. (L) Experimental image (top) and finite element analysis results (bottom) of the e-skin bended around a cylinder with a radius of 100 mm.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/4/2/eaaq0508/DC1

    Supplementary Materials and Methods

    Supplementary Text

    fig. S1. Polymerization of polyimine networks.

    fig. S2 Optical images of sensors.

    fig. S3 Characterizations of sensors under bending and flat states.

    fig. S4. Sensor characterization on integrated platform.

    table S1. Resistance of the original conductive polyimine films.

    table S2. Resistance of the conductive polyimine films after the first recycling.

    table S3. Resistance of the conductive polyimine films after the second recycling.

    table S4. Resistance of the conductive polyimine films after the third recycling.

    Reference (39)

  • Supplementary Materials

    This PDF file includes:

    • Supplementary Materials and Methods
    • Supplementary Text
    • fig. S1. Polymerization of polyimine networks.
    • fig. S2. Optical images of sensors.
    • fig. S3. Characterizations of sensors under bending and flat states.
    • fig. S4. Sensor characterization on integrated platform.
    • table S1. Resistance of the original conductive polyimine films.
    • table S2. Resistance of the conductive polyimine films after the first recycling.
    • table S3. Resistance of the conductive polyimine films after the second recycling.
    • table S4. Resistance of the conductive polyimine films after the third recycling.
    • Reference (39)

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