Research ArticleSOFT ROBOTS

Optical lace for synthetic afferent neural networks

See allHide authors and affiliations

Science Robotics  11 Sep 2019:
Vol. 4, Issue 34, eaaw6304
DOI: 10.1126/scirobotics.aaw6304
  • Fig. 1 Fabrication and design overview.

    (A) Examples of OL without supporting structure showing light coupling (circled in red) in a 2D array (left) and a 3D geometry (right). (B) 3D-printed soft scaffolding with embedded channels for elastomeric light guide cores (left). Eight compression tests of the 3D-printed lattice with 1 SD above and below the average in gray (right). (C) Schematic cross section showing the light guides with close-up of the mechanoreceptor (left). LED illuminating the straight input core and light coupling to an output core when deformed (right).

  • Fig. 2 Experimental validation.

    (A) Sliced x-ray μ-CT scan reconstructions of light guide–lattice composites with contact between cores labeled. Bottom: Magnified isometric and side view of CT reconstructions showing the contact and orientation of the cores at the deformation site under high deformation. (B) Normalized simulated and experimental signals coupled from input to output with varying coupling length and constant contact width (~0.3 mm). Error bars indicate 1 SD above and below average.

  • Fig. 3 Sensor characterization.

    (A) Normalized averaged signal from each output when pressed more than 20 times with increasing force reported with 1 SD above and below. (B) Fastest (black square) and slowest (green triangle) of eight sensor responses to a ~0.1-ms impulse that impacts at time = 0 (marked by a red vertical line). (C) Signal from all three outputs as the OL1,3 is pressed every millimeter along the input from the middle of the left to right outputs. (D) Average calculated versus actual position of eight samples of presses with a dotted line showing where the points would lie if 100% accurate (ground truth). Error bars indicate 1 SD above and below.

  • Fig. 4 Exteroception.

    (A) Musical instrument with 15 output cores. A red LED for visual feedback and the photodiodes for each output core are located on the left side. On the right side, we placed a blue LED to show light to be read by the photodiodes. Direct visual and computed locations of press positions (B) directly on an output, (C) between outputs, and (D) over four outputs simultaneously.

  • Fig. 5 Proprioception.

    (A) Computer-aided design (CAD) model of each component of the cylinder and the completed device with three different stiffness sections. (B) Actual structure, (C) FEA simulated model with strain, and (D) computer-reconstructed cylinder shown during compression. (E) Average displacement error in millimeters between calculated and measured versus normalized displacement for each stiffness section with 1 SD above and below over nine single-axis compression tests.

Supplementary Materials

  • robotics.sciencemag.org/cgi/content/full/4/34/eaaw6304/DC1

    Text

    Fig. S1. Scaffold material properties and mechanical simulation material model.

    Fig. S2. Index of refraction measurement.

    Fig. S3. Dimensions of the OL1,3.

    Fig. S4. μ-CT sample.

    Fig. S5. COMSOL optical simulation results.

    Fig. S6. Experimental setup for coupling length measurements.

    Fig. S7. Experimental setup and results for coupling width measurements.

    Fig. S8. Setup to take force and position data in Fig. 3.

    Fig. S9. Other clear impact testing sensor signals.

    Fig. S10. Curve fit to find nonlinear multiplication factor for Eq. 3.

    Fig. S11. CAD and images of setup for exteroceptive demo.

    Fig. S12. Schematic of information flow.

    Fig. S13. Compression tests of the individual sections in the proprioceptive demo.

    Fig. S14. Schematic of theoretical length model use cases.

    Fig. S15. Increase sensitivity with feather.

    Fig. S16. CAD examples of ways to increase accuracy and resolution.

    Fig. S17. OL3,15.

    Fig. S18. Different geometry OL5,11.

    Fig. S19. Schematic for electronics circuit.

    Fig. S20. Setup for impact test.

    Table S1. Proprioceptive sensor circuit gains.

    Table S2. Linear parameters used in proprioceptive demo to relate signal to force using F = F0 + signal/S1*S2.

    Reference (47)

    Movie S1. High-speed impact.

    Movie S2. Exteroception.

    Movie S3. Proprioception with FEA model.

    Movie S4. Proprioception with experimental model.

    Movie S5. OL3_15.

    Movie S6. Multiple deformation sensing in a block.

    Movie S7. FEA simulation.

  • Supplementary Materials

    The PDF file includes:

    • Text
    • Fig. S1. Scaffold material properties and mechanical simulation material model.
    • Fig. S2. Index of refraction measurement.
    • Fig. S3. Dimensions of the OL1,3.
    • Fig. S4. μ-CT sample.
    • Fig. S5. COMSOL optical simulation results.
    • Fig. S6. Experimental setup for coupling length measurements.
    • Fig. S7. Experimental setup and results for coupling width measurements.
    • Fig. S8. Setup to take force and position data in Fig. 3.
    • Fig. S9. Other clear impact testing sensor signals.
    • Fig. S10. Curve fit to find nonlinear multiplication factor for Eq. 3.
    • Fig. S11. CAD and images of setup for exteroceptive demo.
    • Fig. S12. Schematic of information flow.
    • Fig. S13. Compression tests of the individual sections in the proprioceptive demo.
    • Fig. S14. Schematic of theoretical length model use cases.
    • Fig. S15. Increase sensitivity with feather.
    • Fig. S16. CAD examples of ways to increase accuracy and resolution.
    • Fig. S17. OL3,15.
    • Fig. S18. Different geometry OL5,11.
    • Fig. S19. Schematic for electronics circuit.
    • Fig. S20. Setup for impact test.
    • Table S1. Proprioceptive sensor circuit gains.
    • Table S2. Linear parameters used in proprioceptive demo to relate signal to force using F = F0 + signal/S1*S2.
    • Legends for movies S1 to S7
    • Reference (47)

    Download PDF

    Other Supplementary Material for this manuscript includes the following:

    • Movie S1 (.mp4 format). High-speed impact.
    • Movie S2 (.mp4 format). Exteroception.
    • Movie S3 (.mp4 format). Proprioception with FEA model.
    • Movie S4 (.mp4 format). Proprioception with experimental model.
    • Movie S5 (.mp4 format). OL3_15.
    • Movie S6 (.mp4 format). Multiple deformation sensing in a block.
    • Movie S7 (.mp4 format). FEA simulation.

    Files in this Data Supplement:

Stay Connected to Science Robotics

Navigate This Article