Research ArticleMATERIALS SCIENCE

Leaf-inspired multiresponsive MXene-based actuator for programmable smart devices

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Science Advances  12 Jul 2019:
Vol. 5, no. 7, eaaw7956
DOI: 10.1126/sciadv.aaw7956
  • Fig. 1 The elaborate structure, components, and actuation mechanism of the MXene-cellulose–based actuator.

    (A) Photograph of a natural leaf. (B) Schematic diagram of a leaf structure. (C) Schematic diagram of the MXCC/PC bilayer-structured actuator, which is composed of MXCC and a PC filter membrane. (D) Actuation mechanism of the MXCC/PC bilayer-structured actuator. Macroscopic and microcosmic (involving H bonds) structure changes of the MXCC/PC bilayer-structured actuator in response to hygroscopic and thermal stimuli simultaneously (both hygroscopic and thermal actuation processes are controlled by electrical and NIR light actuation). Scanning electron microscopy images of the MXCC (E) and the PC filter membrane (F). Contact angle measurement of the MXCC (G) and PC filter membrane (H). (I) Transmission electron microscopy image of the 2D MXene nanosheet (inset: SAED pattern).

  • Fig. 2 Multiresponsiveness capabilities and performance of the soft actuators.

    (A) Humidity-responsive capability of the MXCC/PC bilayer-structured actuator [70% RH for AI and AIII, 10% RH for AII and AIV; the downward and upward directions refer to the active MXCC facing down (AI and AII) and up (AIII and AIV), respectively]. (B) Electricity-responsive capability of the MXCC/PC bilayer-structured actuator (power off for BI and BIII, and power on for BII and BIV). (C) NIR light–responsive capability of the MXCC/PC bilayer-structured actuator when NIR light was turned on and off with the active MXCC facing down (CI and CII) and up (CIII and CIV). (D) Temperature change profile as the NIR light was turned on (80 mW cm−2) and off for MXCC-, MXene-, and cellulose-based actuators. (E) IR images of MXCC- and cellulose-based actuators without (EI and EIII) and with (EII and EIV) NIR light illumination (80 mW cm−2). (F) Series of photographs showing the NIR light actuation process of the MXCC/PC bilayer-structured actuator. (G) Bending angle as a function of time during light turned on and off for the actuators based on MXCC and MXene, respectively. (H) Corresponding weight change as a function of time during light turned on and off for the MXCC/PC bilayer-structured actuator. (Photo credit: Guofa Cai, Nanyang Technological University.)

  • Fig. 3 Mechanical performance and motions of the MXCC/PC bilayer-structured actuator caused by NIR light.

    (A) Typical static force and strain changes of the MXCC- and cellulose-based actuators during one actuation cycle when NIR light illumination was turned on and off (50 mW cm−2). (B) Plot of the static force and strain of the MXCC- and cellulose-based actuators as a function of time for five consecutive NIR light on and off cycles, indicating the reversible, stable, and rapid actuation process. (C) Static force changes of the MXCC-based actuator under different NIR illumination intensities (from 5 to 200 mW cm−2). (D) Bending angle of the MXCC-based actuator under different NIR illumination intensities (from 5 to 200 mW cm−2).

  • Fig. 4 Structure change under different NIR illumination intensities and mechanical modeling.

    (A) XRD patterns of MXCC- and MXene-based actuators under different NIR light illumination intensities (solid lines, MXCC-based actuator; dashed lines, MXene-based actuator). (B) Corresponding d-spacing of the MXCC- and MXene-based actuators under different NIR light illumination intensities. (C) Simulated and experimental results of the MXCC-based actuator. (D) Simulated results of the MXCC-based actuator under NIR light illumination.

  • Fig. 5 Representative programmable motions for the MXCC/PC bilayer-structured actuator.

    (A) Double folding U-shape actuator. (B) Trefoil arch–shaped actuator. (C) Self-folding box. (D) Self-blooming flower. Green dashed lines in (C) and (D) (left diagram drawing) are the slight creases created on the bottom of the box and flower to make the self-folding box and self-blooming flower work well under NIR irradiation. (Photo credit: Guofa Cai, Nanyang Technological University.)

  • Fig. 6 Multifunctional smart devices based on MXCC actuators.

    (A) Configuration of a worm-like robot. (B) Mechanical model of the worm-like robot under NIR light irradiation. (C) Photographs of the worm-like robot crawling progressively driven by NIR light irradiation. (D) Configuration of a smart light–controlled switch. (E) Schematic diagram of a light-controlled circuit diagram. The circuit comprises light-controlled switch in series with a smart watch (F) with and (G) without NIR light illumination (80 mW cm−2). (H) Photographs of the patterned MXCC on ordinary A4 paper, illustrating the versatile and programmable MXene-cellulose ink, scalable and low-cost fabrication, and flexible and foldable device (inset). (I) Schematics of the device with patterned MXCC before and after NIR light illumination. (J) IR camera images of the patterned device before and after local NIR irradiation to demonstrate information encryption and display applications. (K) IR camera images of a patterned device with a butterfly-silhouetted MXCC device before and after local NIR irradiation to illustrate the camouflage, display, and actuation applications. The patterned device changes its thermal appearance and stands out from the background upon NIR irradiation. (Photo credit: Guofa Cai, Nanyang Technological University.)

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/7/eaaw7956/DC1

    Fig. S1. The structure and composition of MXene, cellulose, and composites.

    Fig. S2. The microstructure and morphology of the cellulose film and MXene.

    Fig. S3. The MXCC ink and a typical MXCC/PC bilayer-structured actuator.

    Fig. S4. The humidity-responsive capability of the MXCC/PC bilayer-structured actuator.

    Fig. S5. The electricity-responsive capability of the MXCC/PC bilayer-structured actuator.

    Fig. S6. The NIR light-responsive capability of the MXene based actuator.

    Fig. S7. Weight changes as a function of time during light turned on (5 s) and off (600 s) for an MXCC/PDMS bilayer-structured actuator.

    Fig. S8. The experimental setup for measuring static force and strain and cycle performance of the MXCC/PC bilayer-structured actuator.

    Fig. S9. Simulation model of the MXCC-based actuator.

    Fig. S10. NIR light responsiveness of the double folding actuator and the load-lifting capacity of the MXCC-based actuator.

    Note S1. Calculations of the energy density and power density of our MXCC-based actuator.

    Movie S1. A real-time digital camera video of the MXCC/PC bilayer-structured actuator upon sequential on/off NIR light irradiation (illumination intensity, 80 mW cm−2).

    Movie S2. A real-time IR camera video of the MXCC/PC bilayer-structured actuator upon sequential on/off NIR light irradiation (illumination intensity, 80 mW cm−2).

    Movie S3. Simulated actuation process of the MXCC-based actuator.

    Movie S4. A real-time digital camera video of self-folding box upon sequential on/off NIR light irradiation.

    Movie S5. A real-time digital camera video of self-blooming flower upon sequential on/off NIR light irradiation.

    Movie S6. A real-time digital camera video of worm-like robot upon sequential on/off NIR light irradiation.

    Movie S7. A real-time digital camera video of smart switch upon sequential on/off NIR light irradiation.

    Movie S8. A real-time IR camera video of a butterfly silhouette–shaped MXCC device upon sequential on/off NIR light irradiation.

    Reference (43)

  • Supplementary Materials

    The PDF file includes:

    • Fig. S1. The structure and composition of MXene, cellulose, and composites.
    • Fig. S2. The microstructure and morphology of the cellulose film and MXene.
    • Fig. S3. The MXCC ink and a typical MXCC/PC bilayer-structured actuator.
    • Fig. S4. The humidity-responsive capability of the MXCC/PC bilayer-structured actuator.
    • Fig. S5. The electricity-responsive capability of the MXCC/PC bilayer-structured actuator.
    • Fig. S6. The NIR light-responsive capability of the MXene based actuator.
    • Fig. S7. Weight changes as a function of time during light turned on (5 s) and off (600 s) for an MXCC/PDMS bilayer-structured actuator.
    • Fig. S8. The experimental setup for measuring static force and strain and cycle performance of the MXCC/PC bilayer-structured actuator.
    • Fig. S9. Simulation model of the MXCC-based actuator.
    • Fig. S10. NIR light responsiveness of the double folding actuator and the load-lifting capacity of the MXCC-based actuator.
    • Note S1. Calculations of the energy density and power density of our MXCC-based actuator.
    • Legends for movies S1 to S8
    • Reference (43)

    Download PDF

    Other Supplementary Material for this manuscript includes the following:

    • Movie S1 (.avi format). A real-time digital camera video of the MXCC/PC bilayer-structured actuator upon sequential on/off NIR light irradiation (illumination intensity, 80 mW cm−2).
    • Movie S2 (.avi format). A real-time IR camera video of the MXCC/PC bilayer-structured actuator upon sequential on/off NIR light irradiation (illumination intensity, 80 mW cm−2).
    • Movie S3 (.avi format). Simulated actuation process of the MXCC-based actuator.
    • Movie S4 (.avi format). A real-time digital camera video of self-folding box upon sequential on/off NIR light irradiation.
    • Movie S5 (.avi format). A real-time digital camera video of self-blooming flower upon sequential on/off NIR light irradiation.
    • Movie S6 (.avi format). A real-time digital camera video of worm-like robot upon sequential on/off NIR light irradiation.
    • Movie S7 (.avi format). A real-time digital camera video of smart switch upon sequential on/off NIR light irradiation.
    • Movie S8 (.avi format). A real-time IR camera video of a butterfly silhouette–shaped MXCC device upon sequential on/off NIR light irradiation.

    Files in this Data Supplement:

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