Research ArticleAPPLIED SCIENCES AND ENGINEERING

Complex multiphase organohydrogels with programmable mechanics toward adaptive soft-matter machines

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Science Advances  31 Jan 2020:
Vol. 6, no. 5, eaax1464
DOI: 10.1126/sciadv.aax1464
  • Fig. 1 Design strategy and switching mechanism of the organohydrogels.

    (A) Hydrogel framework components are AA, AM, and ANPs; microrganogel inclusions contain SMA, EGDMA, and n-alkanes. (B) Schematic representation of organohydrogels’ programmable multiphase transition mechanism that results from the stepwise noneutectic phase transitions of microrganogels through controlling temperature variations. (C) Confocal laser scanning microscopy image of the organohydrogel heteronetworks with blue-stained hydrogel framework and orange-stained microrganogel inclusions. Scale bar, 5 μm. (D) Illustration showing that the noneutectic triple-phase transitions of organohydrogels. In organohydrogel heteronetwork, these microrganogels contain C16H34, PSMA, and C28H58, which can melt separately by stepwise temperature controlling. (E) Wide-angle x-ray scattering (WAXS) spectra of the organohydrogels demonstrate that the characteristic peaks of C16H34, PSMA, and C28H58 at 10°C. These peaks disappear sequentially as temperature increases to 70°C, indicating the noneutectic triple-phase transition effect of organohydrogels.

  • Fig. 2 Precise programmable mechanics with multistable states of the organohydrogels.

    (A) DSC curve of the organohydrogels exhibits three individual melting peaks, demonstrating organohydrogel triple-phase transitions. As a result, the stepwise triple-switching mechanics of organohydrogels can be realized. The inset photos show that programmable organohydrogels with varying applicable mechanical properties through stepwise manipulation of the noneutectic phase transitions in organohydrogels. Scale bar, 1 cm. (Photo credit: Shuyun Zhuo and Ziguang Zhao, Beihang University). (B and C) Quadruple- and quintuple-switching mechanics of the organohydrogels resulting from multiple modular assembly of corresponding noneutectic phase components within microrganogels. The error bars represent 1 SD (n = 6).

  • Fig. 3 Adaptive grasping of the soft robotic gripper through pneumatic-thermal hybrid actuation and stiffness matching.

    (A) The illustration exhibits the pneumatic-thermal hybrid actuation of the organohydrogel-based gripper. The bending angle of the gripper increases because of thermal-induced modulus decreasing under constant pressure. (B) The bending angles of the gripper at different temperatures. The gripper bends to an angle of 90° as the temperature increased to 63°C in 3 min. The inset images show the infrared pictures of the gripper. (C) Protective grasping is realized through programmably adapting the mechanical properties of the gripper to the target objects. The plasticine ball is damaged during grasping with a rigid gripper (with a modulus of 1.29 MPa) while remains intact with a softened gripper (with a modulus of 0.33 MPa) under electrical stimuli of 18 V and the constant pressure of 25 kPa. (D) Controllable grasping can be obtained through matching the stiffness of the gripper and the targets under a constant grasping force of 1 N. As the modulus of the organohydrogel-based gripper decreases to lower than that of the plasticine, the gripper can adapt to the plasticine without damage. (E) Self-healing performance of the organohydrogel shell of the soft gripper. After being healed at 80°C for 2 hour, the broken gripper outer shell is actuated to a large bending angle with good airtightness. Scale bars, 1 cm. (Photo credit: Shuyun Zhuo, Yufei Hao and Ziguang Zhao, Beihang University).

  • Fig. 4 Programmable adhesion of the octopus-inspired tentacles to rough surfaces.

    (A) Optical images of octopus suckers and the composite octopus-inspired tentacle. Schematic shows the functional organohydrogel-based suckers that integrate the nanotransducer (PPy) with thermoelectric effect into the heteronetworks. (B) The suckers with programmable adaptability enable matching various surface morphologies by manipulating the thermoelectric effect. Note that for the specific objects, the suckers can embed into the surfaces to achieve an effective adhesion. (C) The pull-off force of a sucker on different rough surfaces (the inset scanning electron microscopy images of surfaces with Ra = 0, 20, 50, and 200 μm; scale bars, 100 μm) under modulus (Esucker) of 1.29 MPa. The unit of the time axis has been normalized for ease of force comparison. (D) The pull-off force of a sucker on the surfaces with Ra = 200 μm under different Esucker. The unit of the time axis has been normalized for ease of force comparison. (E) When the suckers have a high modulus of 1.29 MPa, the octopus-inspired tentacles can stick to the specific objects with smooth surfaces (inset photos showing the smooth surface morphologies of a phone and a ball; scale bars, 2 mm). (F) Programmable adaptability to specific objects with complex rough surfaces can be realized through regulating the sucker’ modulus to match surface morphologies (inset photos showing the surface morphologies of a rough resin box and a basketball; scale bars, 1 cm). (Photo credit: Shuyun Zhuo and Zhexin Xie, Beihang University).

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/6/5/eaax1464/DC1

    Section S1. Characterization of microstructure

    Section S2. WAXS measurements and analysis

    Section S3. Optical microscope measurements

    Section S4. DSC measurements and analysis

    Section S5. Measurements of rheological properties

    Section S6. Measurements of mechanical properties

    Section S7. Infrared thermal imaging test of the soft robots

    Section S8. Measurements of self-healing capacity

    Section S9. Measurements of the pull-off force of grippers

    Section S10. Measurements of the controllable grasping performance of grippers

    Section S11. Measurements of the actuation-deactuation cycles of organohydrogel-based soft finger

    Section S12. Sucker attachment force test

    Fig. S1. Characterization and illustration of ANPs.

    Fig. S2. Images of the preparation of the organohydrogels by UV photoinitiated in situ polymerization.

    Fig. S3. Crystallization-melting property of triple-switching organohydrogels.

    Fig. S4. The crystallization/melting enthalpy and crystallinity (χc) of triple-switching organohydrogel.

    Fig. S5. WAXS spectrum of quadruple-switching organohydrogel.

    Fig. S6. WAXS spectrum of quintuple-switching organohydrogel.

    Fig. S7. Mechanical properties of triple-switching organohydrogels at different temperatures.

    Fig. S8. Mechanical properties of quadruple-switching organohydrogel at different temperatures.

    Fig. S9. Mechanical properties of quintuple-switching organohydrogels at different temperatures.

    Fig. S10. Modulus of the organohydrogel at different temperatures during crystallization-melting cycles.

    Fig. S11. Compression modulus of the organohydrogel material at original state and on the 50th crystallization-melting cycle [df = 1, F = 0.01, and P = 0.975, analysis of variance (ANOVA)].

    Fig. S12. Images of the grippers’ components.

    Fig. S13. DSC curve of the organohydrogel materials for soft-matter machines.

    Fig. S14. The actuation process of the traditional silicone-based gripper and organohydrogel-based gripper.

    Fig. S15. Infrared images of the gripper from the top view showing its increased temperature by powered at different voltages.

    Fig. S16. The pull-off force of a single gripper at different voltages under constant pressure (25 kPa).

    Fig. S17. Pressure (P)–bending angle (α) curves of actuation-deactuation cycles of the soft finger at different temperatures.

    Fig. S18. Schematic of the structured organohydrogel-based soft gripper.

    Fig. S19. Self-healing property of the organohydrogel.

    Fig. S20. The influence of self-healing property on the soft finger’ working life span.

    Fig. S21. Fabrication of the octopus-inspired tentacles.

    Fig. S22. Compression modulus of organohydrogel and organohydrogel PPy at different temperatures.

    Fig. S23. Infrared images of the octopus-inspired tentacle at different voltages.

    Fig. S24. The temperature-time relationship of the organohydrogel-based soft robots under different voltages.

    Fig. S25. The pull-off force of a single sucker on the surfaces with different roughnesses under varied electrical stimuli.

    Fig. S26. Photos from the top view of different surfaces.

    Table S1. Mechanical characteristics of triple-switching organohydrogels at different temperatures.

    Table S2. Mechanical characteristics of quadruple-switching organohydrogels at different temperatures.

    Table S3. Mechanical characteristics of quintuple-switching organohydrogels at different temperatures.

    Table S4. Mechanical characteristics of the original and self-healed organohydrogels.

    Movie S1. Pneumatic-thermal hybrid actuation of the organohydrogel-based soft gripper.

    Movie S2. Repeated heating-actuating-cooling cycles of the soft gripper.

    Movie S3. Adaptive grasping performance of the soft gripper.

    Movie S4. Protective grasping through matching the modulus of the soft gripper and the object.

    Movie S5. Adhesion on and grasping a phone on the smooth flat surface.

    Movie S6. Adhesion on and grasping a rubber ball on the smooth curved surface.

    Movie S7. Programmable adhesion on the rough flat surface of a resin box.

    Movie S8. Programmable adhesion on the rough curved surface of a basketball.

  • Supplementary Materials

    The PDFset includes:

    • Section S1. Characterization of microstructure
    • Section S2. WAXS measurements and analysis
    • Section S3. Optical microscope measurements
    • Section S4. DSC measurements and analysis
    • Section S5. Measurements of rheological properties
    • Section S6. Measurements of mechanical properties
    • Section S7. Infrared thermal imaging test of the soft robots
    • Section S8. Measurements of self-healing capacity
    • Section S9. Measurements of the pull-off force of grippers
    • Section S10. Measurements of the controllable grasping performance of grippers
    • Section S11. Measurements of the actuation-deactuation cycles of organohydrogel-based soft finger
    • Section S12. Sucker attachment force test
    • Fig. S1. Characterization and illustration of ANPs.
    • Fig. S2. Images of the preparation of the organohydrogels by UV photoinitiated in situ polymerization.
    • Fig. S3. Crystallization-melting property of triple-switching organohydrogels.
    • Fig. S4. The crystallization/melting enthalpy and crystallinity (χc) of triple-switching organohydrogel.
    • Fig. S5. WAXS spectrum of quadruple-switching organohydrogel.
    • Fig. S6. WAXS spectrum of quintuple-switching organohydrogel.
    • Fig. S7. Mechanical properties of triple-switching organohydrogels at different temperatures.
    • Fig. S8. Mechanical properties of quadruple-switching organohydrogel at different temperatures.
    • Fig. S9. Mechanical properties of quintuple-switching organohydrogels at different temperatures.
    • Fig. S10. Modulus of the organohydrogel at different temperatures during crystallization-melting cycles.
    • Fig. S11. Compression modulus of the organohydrogel material at original state and on the 50th crystallization-melting cycle df = 1, F = 0.01, and P = 0.975, analysis of variance (ANOVA).
    • Fig. S12. Images of the grippers’ components.
    • Fig. S13. DSC curve of the organohydrogel materials for soft-matter machines.
    • Fig. S14. The actuation process of the traditional silicone-based gripper and organohydrogel-based gripper.
    • Fig. S15. Infrared images of the gripper from the top view showing its increased temperature by powered at different voltages.
    • Fig. S16. The pull-off force of a single gripper at different voltages under constant pressure (25 kPa).
    • Fig. S17. Pressure (P)–bending angle (α) curves of actuation-deactuation cycles of the soft finger at different temperatures.
    • Fig. S18. Schematic of the structured organohydrogel-based soft gripper.
    • Fig. S19. Self-healing property of the organohydrogel.
    • Fig. S20. The influence of self-healing property on the soft finger’ working life span.
    • Fig. S21. Fabrication of the octopus-inspired tentacles.
    • Fig. S22. Compression modulus of organohydrogel and organohydrogel PPy at different temperatures.
    • Fig. S23. Infrared images of the octopus-inspired tentacle at different voltages.
    • Fig. S24. The temperature-time relationship of the organohydrogel-based soft robots under different voltages.
    • Fig. S25. The pull-off force of a single sucker on the surfaces with different roughnesses under varied electrical stimuli.
    • Fig. S26. Photos from the top view of different surfaces.
    • Table S1. Mechanical characteristics of triple-switching organohydrogels at different temperatures.
    • Table S2. Mechanical characteristics of quadruple-switching organohydrogels at different temperatures.
    • Table S3. Mechanical characteristics of quintuple-switching organohydrogels at different temperatures.
    • Table S4. Mechanical characteristics of the original and self-healed organohydrogels.
    • Legends for movies S1 to S8

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    Other Supplementary Material for this manuscript includes the following:

    • Movie S1 (.mp4 format). Pneumatic-thermal hybrid actuation of the organohydrogel-based soft gripper.
    • Movie S2 (.mp4 format). Repeated heating-actuating-cooling cycles of the soft gripper.
    • Movie S3 (.mp4 format). Adaptive grasping performance of the soft gripper.
    • Movie S4 (.mp4 format). Protective grasping through matching the modulus of the soft gripper and the object.
    • Movie S5 (.mp4 format). Adhesion on and grasping a phone on the smooth flat surface.
    • Movie S6 (.mp4 format). Adhesion on and grasping a rubber ball on the smooth curved surface.
    • Movie S7 (.mp4 format). Programmable adhesion on the rough flat surface of a resin box.
    • Movie S8 (.mp4 format). Programmable adhesion on the rough curved surface of a basketball.

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