Research ArticleAPPLIED SCIENCES AND ENGINEERING

Climbing-inspired twining electrodes using shape memory for peripheral nerve stimulation and recording

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Science Advances  19 Apr 2019:
Vol. 5, no. 4, eaaw1066
DOI: 10.1126/sciadv.aaw1066
  • Fig. 1 Twining electrodes for PNS.

    (A) Schematic diagram of the conceptual PNS neuromodulation for restoring the motor and physiological functions (left) and the electrode-nerve interface (right). (B and C) Concept of the self-climbing process from the flattened state driven by body temperature. (D) Photographs of the twining plants during deformation. (E) Layout of the proposed twining electrode. (F) Twining electrode in the temporarily flattened state. ACF, anisotropic conductive film. (G) Twining electrode that recovered from its temporary shape (inner diameter of ~2 mm). Photo credit: Yingchao Zhang, Tsinghua University.

  • Fig. 2 Schematic illustrations of the detailed fabrication process of the twining electrode and images of the self-climbing process.

    (A and B) Mesh serpentine design of the Au/Ti layer and the PI film, respectively. (C and D) Transfer printing process of the mesh serpentine Au/Ti/PI from Si onto the SMP substrate. (E and F) Reconfiguration of the permanent shape from the 2D planar shape to the designed 3D helical shape. (G to I) Schematic illustrations of the surgical implantation processes of the twining electrode with the aid of the shape memory effect. (J) Images of the in vitro experiments and the self-climbing processes of the twining electrode on a glass rod. Photo credit: Yingchao Zhang, Tsinghua University.

  • Fig. 3 Materials characterization.

    (A) DSC curve for the synthetic SMPs. (B) Consecutive elasticity (shape memory) cycles. (C and D) CDC and impedance spectroscopy of the electrode under four different states.

  • Fig. 4 Structure optimization.

    (A) r0/r versus hSMP at several different hPI. (B) r0/r versus hPI at several different hSMP. (C) FEA models of three deformations of the nerve. (D) Maximum strain in the Au layer under the three deformations. (E to G) Comparisons of the normal stress applied on the nerve between the traditional helical electrode and the twining electrode under the three deformations.

  • Fig. 5 Photographs and ECG data from the in vivo VNS animal experiments.

    (A) Schematic diagram of VNS and recording of ECG (left) and images of an implanted twining electrode (inner diameter of 1 mm) on the vagus nerve (right). (B1 to B6) Images of the surgical implantation procedures of the twining electrode. (C and D) Illustrations of the twining electrode that conformally contacts the deforming vagus nerve. (E to G) ECGs of the anesthetized rabbit in a normal state (E), after epinephrine injection (F), and during electrical stimulation (G). Photo credit: Yingchao Zhang, Tsinghua University.

  • Fig. 6 In vivo recording of the rabbit’s sciatic nerve using the twining electrodes.

    (A and B) Schematic diagram of the in vivo experimental setup. (C) Bipolar twining electrodes integrated on the sciatic nerve for recording. (D) Recorded CNAPs evoked by varying current (0.10, 0.15, and 0.3 mA). (E) Enlarged view of the comparison between the three evoked CNAPs. (F) Recorded CNAPs evoked by the shaking of the anesthetized rabbit’s leg (without electrical stimulation). Photo credit: Yingchao Zhang, Tsinghua University.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/4/eaaw1066/DC1

    Note S1. Recoverability of the twining electrode and the maximum strain in the Au layer.

    Note S2. Comparison of bending stiffness.

    Note S3. Comparison of tension stiffness.

    Note S4. Calculation of the SNR.

    Fig. S1. Design of the SMP network and the mechanistic illustration of reconfiguration (plastic) and recovery (elastic).

    Fig. S2. Chemical network of the precursor monomers and the synthesized SMPs.

    Fig. S3. Characterization of the thickness of the Au/Ti and PI layers.

    Fig. S4. Characterization of the SMP.

    Fig. S5. Cyclic voltammogram.

    Fig. S6. Impedance spectroscopy.

    Fig. S7. Mechanical model for the twining electrode and the corresponding results.

    Fig. S8. FEA models and results for EA.

    Fig. S9. The parameters used in the FEA and the corresponding FEA model.

    Fig. S10. The FEA comparison results of the normal and shear stress applied on the nerve under three deformation modes.

    Fig. S11. Calculations of the recorded SNR.

    Table S1. Comparison of (EI)Twining and (EI)Tradition.

    Movie S1. Twining plants under complex deformations.

    Movie S2. The twining electrode is twined on a glass rod driven by 37°C water.

    Movie S3. The electrical conductivity test.

    Movie S4. The demonstration of the recovery of the twining electrode upon physiology temperature.

    Movie S5. The illustration of the mechanical reliability of the twining electrode under stretching and bending.

    Movie S6. The in vivo self-climbing on vagus nerve process of the twining electrode.

    Movie S7. The self-adaptive adjustment of the twining electrode.

    Movie S8. The twining electrode conformally contacts with the deforming vagus nerve.

    Movie S9. The activated moments of the leg of the anesthetized rabbit.

  • Supplementary Materials

    The PDF file includes:

    • Note S1. Recoverability of the twining electrode and the maximum strain in the Au layer.
    • Note S2. Comparison of bending stiffness.
    • Note S3. Comparison of tension stiffness.
    • Note S4. Calculation of the SNR.
    • Fig. S1. Design of the SMP network and the mechanistic illustration of reconfiguration (plastic) and recovery (elastic).
    • Fig. S2. Chemical network of the precursor monomers and the synthesized SMPs.
    • Fig. S3. Characterization of the thickness of the Au/Ti and PI layers.
    • Fig. S4. Characterization of the SMP.
    • Fig. S5. Cyclic voltammogram.
    • Fig. S6. Impedance spectroscopy.
    • Fig. S7. Mechanical model for the twining electrode and the corresponding results.
    • Fig. S8. FEA models and results for EA.
    • Fig. S9. The parameters used in the FEA and the corresponding FEA model.
    • Fig. S10. The FEA comparison results of the normal and shear stress applied on the nerve under three deformation modes.
    • Fig. S11. Calculations of the recorded SNR.
    • Table S1. Comparison of (EI)Twining and (EI)Tradition.

    Download PDF

    Other Supplementary Material for this manuscript includes the following:

    • Movie S1 (.mp4 format). Twining plants under complex deformations.
    • Movie S2 (.mp4 format). The twining electrode is twined on a glass rod driven by 37°C water.
    • Movie S3 (.mp4 format). The electrical conductivity test.
    • Movie S4 (.mp4 format). The demonstration of the recovery of the twining electrode upon physiology temperature.
    • Movie S5 (.mp4 format). The illustration of the mechanical reliability of the twining electrode under stretching and bending.
    • Movie S6 (.mp4 format). The in vivo self-climbing on vagus nerve process of the twining electrode.
    • Movie S7 (.mp4 format). The self-adaptive adjustment of the twining electrode.
    • Movie S8 (.mp4 format). The twining electrode conformally contacts with the deforming vagus nerve.
    • Movie S9 (.mp4 format). The activated moments of the leg of the anesthetized rabbit.

    Files in this Data Supplement:

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