Research ArticleSOFT ROBOTS

Multifunctional metallic backbones for origami robotics with strain sensing and wireless communication capabilities

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Science Robotics  28 Aug 2019:
Vol. 4, Issue 33, eaax7020
DOI: 10.1126/scirobotics.aax7020
  • Fig. 1 GO-enabled templating synthesis of noble metal replicas.

    (A) The GO-enabled templating synthesis for transforming cellulose paper to noble metal replicas. The synthesis of a phoenix-shaped Pt replica is demonstrated. The SEM images showed that the network morphologies of cellulose paper and GO-cellulose template were very similar. The diameter of microfibers decreased from ~20 to ~6 μm after two-stage annealing/calcination. (B) XRD spectra of as-synthesized metal replicas after two-stage annealing/calcination. The spectra were consistent with their corresponding “powder diffraction files (PDF)” from “joint committee on powder diffraction standards.” (C) Weight percentages of metallic contents in the templated replicas after the calcination in air at different temperatures. The weight percentages are determined by EDS analysis. (D) Resistance of templated metal replicas (across 1 cm) after the calcination in air at different temperatures. The error bars indicate the differences in measurements from four samples.

  • Fig. 2 Fabrication of metal origami structures.

    (A) Photos of the fourfold and auxetic hexagonal metal origami products synthesized from cellulose-only (top row) and GO-cellulose templates (bottom row). Pt-based products at different annealing/calcination stages are shown. SEM images of Pt products synthesized from (B) cellulose-only and (C) GO-cellulose templates. (D) Photos of GO-cellulose origami and as-templated downsized Pt origami replicas, including (i) honeycomb, (ii) frog, (iii) flower, (iv) dinosaur, (v) airplane, and (vi) bellows tube.

  • Fig. 3 Turning Pt origami replicas into deformable Pt-elastomer metamaterials.

    (A) Infiltration of dilute elastomer liquid into templated Pt replicas enables the fabrication of Pt-elastomer metamaterials. (B) Top-down and cross-sectional SEM images of Pt-elastomer composite. The thickness of Pt-elastomer composite is about 90 μm. (C) Large deformability of a planar Pt-elastomer thin film (180° bending, 360° twisting, and 30% stretching). (D) Stress-strain curves of a Pt-elastomer auxetic hexagonal origami during the stability test for 200 cycles. (E) In situ SEM images with EDS mapping of a Pt-elastomer crease under 90% uniaxial stretching. (F) The patterns of Pt-elastomer auxetic hexagonal origami is strain dependent during the uniaxial compressing (marked with −1 to −3) and stretching processes (marked with 1 to 5). The figure marked with 0 represented the initial state. (G) Resistance changes of a flat Pt-elastomer film under bending from 0° to 180°. (H) Relative resistance changes of auxetic hexagonal and bellows Pt-elastomer origamis under various uniaxial strains. Rs is the resistance of Pt-elastomer origami under uniaxial strains; R0 is the resistance of unstrained Pt-elastomer origami.

  • Fig. 4 Origami Pt robot with distinct capabilities.

    (A) Bellows-type Pt robot remained intact after 30-s fire test, whereas paper robot was ignited. (B) Robotic displacement and corresponding gas pressure of bellows-type Pt and paper robots. Both robots were fabricated with the same size (height, 2 cm; length, 3.5 cm). (C) Relative resistance changes of auxetic hexagonal–type Pt actuators (by nitinol wires) and bellows-type Pt robot (actuated by a pneumatic pump) under various strains. (D) Relative resistance changes of a bellows-type Pt robot during the actuation frequency at 1.2 Hz. (E) Surface temperature profiles of a bellows-type Pt robot as a function of time under 5, 10, 15, and 20 V. (F) Cycling test of resistive heating performance of a Pt robot under an applied voltage of 20 V.

  • Fig. 5 Origami Pt robot with built-in wireless communication capabilities.

    (A) Simulated 3D radiation patterns for two Pt-elastomer bellows tubes at 741.8 MHz under 0% strain. (B) Schematic demonstration of a dual-bellows Pt robot, which also served as a reconfigurable dipole antenna. (C) Left: Return loss of the reconfigurable dipole antenna under different compressive strains from 0 to 50%. Right: The resonant frequencies are a function of compressive strains before and after 500-cycle robotic actuations. (D) Photograph of a sender Pt robot (sending signals) (left) and a receiver Pt robot (receiving signals) (right). (E) The pulse signals (the sender Pt robot sent) were well received by the receiver Pt robot. The frequency of sent signals was identical to the received signals. (F) Two Pt robots were able to communicate remotely across 1.2-m distance.

  • Fig. 6 Demonstrations of multifunctional Pt robots.

    (A) Single-bellows Pt robot with built-in resistive heating capability. Two Pt robots were frozen in ice cubes. Under an applied voltage of 20 V, the upper Pt robot was quickly heated to ca. 80°C in 60 s, escaped from the ice, and continued to crawl forward. (B) Dual-bellows Pt robot with built-in strain sensing capability. The Pt robotic backbones were connected with copper wires, and the connection was fixed using silver paste. The proposed pathway for the dual-bellows Pt robot involved (i) crawling straight, (ii) turning right, and (iii) turning left. The robotic actuations along the whole pathway were monitored by reading the current profiles of left and right Pt bellows tubes. (C) Wireless communication between two dual-bellows Pt robots. The sender robot was blocked by an obstacle on the projected pathway and turned left to bypass the obstacle. The sender robot sent a series of signals to the receiver robot. The signals were then interpreted into the moving guideline for the receiver robot, enabling the robot to take the proposed pathway without encountering the obstacle.

  • Fig. 7 Fabrication of magnetically actuated Pt robot via Pt-GO-cellulose ink.

    (A) Alternative fabrication of Pt robots was demonstrated by developing Pt-GO-cellulose ink and incorporating with FDM 3D printing. After two-stage annealing/calcination, PDMS stabilization, and embedding with Nd–Fe–B particles, a magnetically actuated Pt–(Nd–Fe–B) tetrapod robot was fabricated. (B) Built-in strain sensing and wireless communication capabilities of Pt–(Nd–Fe–B) tetrapod robot. (C) Pt–(Nd–Fe–B) tetrapod robot arched up and down under magnetic actuations. (D) Pt–(Nd–Fe–B) tetrapod robot moved forward by following the trajectories of rotating magnetic fields.

Supplementary Materials

  • robotics.sciencemag.org/cgi/content/full/4/33/eaax7020/DC1

    Fig. S1. XRD spectra of GO after metal ion intercalation and after first-stage annealing.

    Fig. S2. Photos and SEM images of cellulose paper, GO-cellulose template, C/metal intermediate products, and metal replicas.

    Fig. S3. SEM images and EDS analysis of Ag products after the calcination in air at different temperatures.

    Fig. S4. SEM images and EDS analysis of Au products after the calcination in air at different temperatures.

    Fig. S5. SEM images and EDS analysis of Pt products after the calcination in air at different temperatures.

    Fig. S6. Raman spectra of Pt replicas after the calcination in air at different temperatures.

    Fig. S7. Cross-sectional SEM images of Ag, Au, and Pt products after the calcination in air at different temperatures.

    Fig. S8. Thickness, dimension shrinkage, and mechanical properties of noble metal replicas.

    Fig. S9. Weight changes of Pt-GO-cellulose and Pt-cellulose origamis at different annealing/calcination stages.

    Fig. S10. EDS mapping analysis of Pt products from GO-cellulose and cellulose-only templates.

    Fig. S11. TEM image of annealed Pt nanocrystals from Pt-GO-cellulose template.

    Fig. S12. Engineering thickness and electrical conductivity of Pt-elastomer backbones.

    Fig. S13. Stress-strain curves of cellulose papers, PDOT-PSS–infiltrated papers, MWNT-infiltrated papers, copper film on silicon, planar Pt replica, and Pt-PDMS films.

    Fig. S14. Relative resistance changes of a flat Pt-PDMS film under repetitive 90° bending.

    Fig. S15. Photos of the bellows tubes of paper predecessor and the elastomer-stabilized Pt replica.

    Fig. S16. Design of single-bellows Pt robot with friction feet.

    Fig. S17. SEM image of commercial cellulose paper.

    Fig. S18. Digital photo of pneumatic single-bellows paper and Pt robots.

    Fig. S19. Performances of Pt robot, paper robot, and AF robot.

    Fig. S20. Fabrication process of pneumatic dual-bellows Pt robot.

    Fig. S21. Design of dual-bellows Pt robot with friction feet.

    Fig. S22. Return loss of dual-bellows Pt robot with a broad bandwidth from 0 to 1200 MHz.

    Fig. S23. Simulation results of reconfigurable dipole Pt antenna (i.e., dual-bellows Pt robot).

    Fig. S24. Strain sensing of flat Pt-PDMS composites with different amounts of carbon.

    Fig. S25. Return loss of dipole antennas made from flat Pt-PDMS films with different amounts of carbon.

    Fig. S26. Relative resistance changes under various uniaxial strains of various dual-bellows robots, including Pt robot, AF robot, MWNT robot, and PDOT robot.

    Fig. S27. Return loss of different reconfigurable dipole antennas (i.e., dual-bellows robots), including Pt robot, PDOT robot, MWNT robot, and AF robot.

    Fig. S28. SEM image of Nd-Fe-B particles.

    Fig. S29. Return loss of hexagonal honeycomb Pt-elastomer origami.

    Fig. S30. Assembly of an enclosed bellows Pt tube.

    Table S1. Comparison among various possible backbone materials.

    Movie S1. Comparison of gas pressure between paper and Pt robots.

    Movie S2. Origami Pt robot with built-in resistive heating.

    Movie S3. Origami Pt robot with built-in strain sensing.

    Movie S4. Wireless communication of origami Pt robots.

    Movie S5. Magnetically actuated Pt-(Nd-Fe-B) tetrapod robot.

  • Supplementary Materials

    The PDF file includes:

    • Fig. S1. XRD spectra of GO after metal ion intercalation and after first-stage annealing.
    • Fig. S2. Photos and SEM images of cellulose paper, GO-cellulose template, C/metal intermediate products, and metal replicas.
    • Fig. S3. SEM images and EDS analysis of Ag products after the calcination in air at different temperatures.
    • Fig. S4. SEM images and EDS analysis of Au products after the calcination in air at different temperatures.
    • Fig. S5. SEM images and EDS analysis of Pt products after the calcination in air at different temperatures.
    • Fig. S6. Raman spectra of Pt replicas after the calcination in air at different temperatures.
    • Fig. S7. Cross-sectional SEM images of Ag, Au, and Pt products after the calcination in air at different temperatures.
    • Fig. S8. Thickness, dimension shrinkage, and mechanical properties of noble metal replicas.
    • Fig. S9. Weight changes of Pt-GO-cellulose and Pt-cellulose origamis at different annealing/calcination stages.
    • Fig. S10. EDS mapping analysis of Pt products from GO-cellulose and cellulose-only templates.
    • Fig. S11. TEM image of annealed Pt nanocrystals from Pt-GO-cellulose template.
    • Fig. S12. Engineering thickness and electrical conductivity of Pt-elastomer backbones.
    • Fig. S13. Stress-strain curves of cellulose papers, PDOT-PSS–infiltrated papers, MWNT-infiltrated papers, copper film on silicon, planar Pt replica, and Pt-PDMS films.
    • Fig. S14. Relative resistance changes of a flat Pt-PDMS film under repetitive 90° bending.
    • Fig. S15. Photos of the bellows tubes of paper predecessor and the elastomer-stabilized Pt replica.
    • Fig. S16. Design of single-bellows Pt robot with friction feet.
    • Fig. S17. SEM image of commercial cellulose paper.
    • Fig. S18. Digital photo of pneumatic single-bellows paper and Pt robots.
    • Fig. S19. Performances of Pt robot, paper robot, and AF robot.
    • Fig. S20. Fabrication process of pneumatic dual-bellows Pt robot.
    • Fig. S21. Design of dual-bellows Pt robot with friction feet.
    • Fig. S22. Return loss of dual-bellows Pt robot with a broad bandwidth from 0 to 1200 MHz.
    • Fig. S23. Simulation results of reconfigurable dipole Pt antenna (i.e., dual-bellows Pt robot).
    • Fig. S24. Strain sensing of flat Pt-PDMS composites with different amounts of carbon.
    • Fig. S25. Return loss of dipole antennas made from flat Pt-PDMS films with different amounts of carbon.
    • Fig. S26. Relative resistance changes under various uniaxial strains of various dual-bellows robots, including Pt robot, AF robot, MWNT robot, and PDOT robot.
    • Fig. S27. Return loss of different reconfigurable dipole antennas (i.e., dual-bellows robots), including Pt robot, PDOT robot, MWNT robot, and AF robot.
    • Fig. S28. SEM image of Nd-Fe-B particles.
    • Fig. S29. Return loss of hexagonal honeycomb Pt-elastomer origami.
    • Fig. S30. Assembly of an enclosed bellows Pt tube.
    • Table S1. Comparison among various possible backbone materials.
    • Legends for movies S1 to S5

    Download PDF

    Other Supplementary Material for this manuscript includes the following:

    • Movie S1 (.mp4 format). Comparison of gas pressure between paper and Pt robots.
    • Movie S2 (.mp4 format). Origami Pt robot with built-in resistive heating.
    • Movie S3 (.mp4 format). Origami Pt robot with built-in strain sensing.
    • Movie S4 (.mp4 format). Wireless communication of origami Pt robots.
    • Movie S5 (.mp4 format). Magnetically actuated Pt-(Nd-Fe-B) tetrapod robot.

    Files in this Data Supplement:

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