Research ArticleMATERIALS SCIENCE

Surface-agnostic highly stretchable and bendable conductive MXene multilayers

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Science Advances  09 Mar 2018:
Vol. 4, no. 3, eaaq0118
DOI: 10.1126/sciadv.aaq0118
  • Fig. 1 Structural and morphological characterizations of MXene multilayers.

    (A) Schematic of the PDAC/MXene LbL assembly process. Images of (B) immersion and (C) spray assembly of multilayer coatings of varying number of layer pairs on glass. (D) A cross-sectional SEM image of the multilayer coating. (E) Ultraviolet–visible (UV-vis) spectra of MXene multilayers on glass. (F) Absorbance values at 770 nm versus number of layer pairs. a.u., arbitrary units. (G) Growth profile of the multilayers on glass. (H) Root-mean-square (RMS) roughness versus number of layer pairs.

  • Fig. 2 Surface-agnostic conductive coatings.

    (A) Digital images of 40-layer-pair coatings on various substrates (sheet resistance of coatings on slide glass, PDMS, PET, and kirigami PET: 7, 7, 4, and 4 kilohm per square, respectively). (B) A digital image and SEM images of bare nylon fiber and 20-layer-pair–coated nylon fiber. (C) Images to demonstrate conductive coating on nylon fiber (R = 26.5 megohm). (D) Sheet resistance of the MXene multilayers on glass. (E) Schematic illustration of an electric circuit with a battery, a light-emitting diode (LED), and the MXene multilayer (LbL film). Digital images to demonstrate the conductive coating on PET under bending and folding.

  • Fig. 3 Strain sensor behavior under bending and stretching.

    (A) Normalized resistance (R/R0) versus bending radius for 20-layer-pair MXene multilayer on PET and (B) versus strain for 20-layer-pair MXene multilayer on PDMS. R0 = 22.4 kilohm (bending) and 1.66 megohm (stretching). Cycling performance under (C) bending and (D) stretching. SEM images of the surface structure of the 20-layer-pair MXene multilayer on (E) PET (bending) and (F) PDMS (stretching). The deformed coatings on PET and PDMS are under bending (r = 4.4 mm) and stretching (ε = 20%), respectively.

  • Fig. 4 An object scanner and human motion sensor.

    (A) Digital image of a topographical scanner using the MXene multilayer–coated PET (LbL sensor). (B) The topographical map by normalized resistance variations with various cube patterns. (C) Topographical scanner with the five MXene multilayer–coated PET sensors and (D) T, A, M, and U patterns using cubes. (E) Topographical maps of normalized resistance variations for the T, A, M, and U patterns. (F) Digital image of the human motion strain sensor. (G) Response to finger motion.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/4/3/eaaq0118/DC1

    fig. S1. TEM image of a Ti3C2 MXene nanosheet on a perforated carbon grid.

    fig. S2. Digital images of (left) bare glass, (middle) the result of LbL assembly using only MXene sheets (without PDAC solution), and (right) 10-layer-pair MXene/PDAC multilayer coating.

    fig. S3. Adhesion testing with tape.

    fig. S4. A cross-sectional SEM image of the MXene multilayer prepared by spray-assisted LbL assembly on glass.

    fig. S5. AFM images of PDAC/MXene multilayers.

    fig. S6. Thickness of the multilayers as a function of the number of layer pairs.

    fig. S7. ATR-FTIR spectra of MXene, PDAC, and 20-layer-pair MXene multilayer coating.

    fig. S8. XPS survey spectra of MXene, (PDAC/MXene)20 multilayer finished with MXene, and (PDAC/MXene)20.5 multilayer finished with PDAC.

    fig. S9. XRD of MXene powder and multilayer.

    fig. S10. Digital images of MXene multilayers bending and stretching.

    fig. S11. Normalized resistance for bending and stretching.

    fig. S12. Comparison of resistance drift in literature.

    fig. S13. Images and normalized resistance of MXene multilayers on a variety of substrates.

    fig. S14. SEM images of MXene multilayers after bending and stretching.

    fig. S15. Geometric analysis of defects in bending.

    fig. S16. Geometric analysis of defects in stretching.

    fig. S17. A multilayer strain sensor.

    fig. S18. Strain versus the angle at the index finger.

    table S1. Atomic composition at the surface of cast MXene sheets, (PDAC/MXene)20 multilayer terminated with MXene, and (PDAC/MXene)20.5 multilayer terminated with PDAC from XPS survey spectra (fig. S8).

    table S2. Characteristics of flexible MXene-based films or coatings.

    table S3. Characteristics of reported bendable conductors.

    table S4. Characteristics of reported stretchable conductors.

    movie S1. A nylon fiber coated with a MXene multilayer, showing conductive properties.

    movie S2. An MXene multilayer on PET lights up a white LED under folding.

    movie S3. Cyclic bending of a MXene multilayer on PET shows rapid and reversible response.

    movie S4. An MXene multilayer on PET detects bending deformations.

    movie S5. A kirigami MXene multilayer on PET detects stretching deformations.

    movie S6. A kirigami pattern allows MXene multilayer–coated PET to be stretchable.

    movie S7. An MXene multilayer on PDMS detects stretching deformations.

    movie S8. An MXene multilayer on PDMS detects a twisting deformation.

    movie S9. A patterned multilayer strain sensor detects various degrees of bending (0° to 40°) with rapid response.

    movie S10. A topographic scanner was fabricated using a patterned MXene multilayer–coated PET film.

    References (2961)

  • Supplementary Materials

    This PDF file includes:

    • fig. S1. TEM image of a Ti3C2 MXene nanosheet on a perforated carbon grid.
    • fig. S2. Digital images of (left) bare glass, (middle) the result of LbL assembly using only MXene sheets (without PDAC solution), and (right) 10-layer-pair MXene/PDAC multilayer coating.
    • fig. S3. Adhesion testing with tape.
    • fig. S4. A cross-sectional SEM image of the MXene multilayer prepared by spray-assisted LbL assembly on glass.
    • fig. S5. AFM images of PDAC/MXene multilayers.
    • fig. S6. Thickness of the multilayers as a function of the number of layer pairs.
    • fig. S7. ATR-FTIR spectra of MXene, PDAC, and 20-layer-pair MXene multilayer coating.
    • fig. S8. XPS survey spectra of MXene, (PDAC/MXene)20 multilayer finished with MXene, and (PDAC/MXene)20.5 multilayer finished with PDAC.
    • fig. S9. XRD of MXene powder and multilayer.
    • fig. S12. Comparison of resistance drift in literature.
    • fig. S13. Images and normalized resistance of MXene multilayers on a variety of substrates.
    • fig. S14. SEM images of MXene multilayers after bending and stretching.
    • fig. S15. Geometric analysis of defects in bending.
    • fig. S16. Geometric analysis of defects in stretching.
    • fig. S17. A multilayer strain sensor.
    • fig. S18. Strain versus the angle at the index finger.
    • table S1. Atomic composition at the surface of cast MXene sheets, (PDAC/MXene)20 multilayer terminated with MXene, and (PDAC/MXene)20.5 multilayer terminated with PDAC from XPS survey spectra (fig. S8).
    • table S2. Characteristics of flexible MXene-based films or coatings.
    • table S3. Characteristics of reported bendable conductors.
    • table S4. Characteristics of reported stretchable conductors.
    • Legends for movies S1 to S10
    • References (29–61)

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    Other Supplementary Material for this manuscript includes the following:

    • movie S1(.mov format). A nylon fiber coated with a MXene multilayer, showing conductive properties.
    • movie S2 (.mov format). An MXene multilayer on PET lights up a white LED under folding.
    • movie S3 (.mov format). Cyclic bending of a MXene multilayer on PET shows rapid and reversible response.
    • movie S4 (.mov format). An MXene multilayer on PET detects bending deformations.
    • movie S5 (.mov format). A kirigami MXene multilayer on PET detects stretching deformations.
    • movie S6 (.mov format). A kirigami pattern allows MXene multilayer–coated PET to be stretchable.
    • movie S7 (.mov format). An MXene multilayer on PDMS detects stretching deformations.
    • movie S8 (.mov format). An MXene multilayer on PDMS detects a twisting deformation.
    • movie S9 (.mov format). A patterned multilayer strain sensor detects various degrees of bending (0° to 40°) with rapid response.
    • movie S10 (.mov format). A topographic scanner was fabricated using a patterned MXene multilayer–coated PET film.

    Files in this Data Supplement:

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