Research ArticleENGINEERING

Stretchable elastic synaptic transistors for neurologically integrated soft engineering systems

See allHide authors and affiliations

Science Advances  11 Oct 2019:
Vol. 5, no. 10, eaax4961
DOI: 10.1126/sciadv.aax4961
  • Fig. 1 Fully rubbery synaptic transistors.

    (A) Schematic illustration of the deformable synapse and its synaptic transmission process in an earthworm. (B) Optical images of the fully rubbery synaptic transistor under different levels (0, 10, 30, and 50%) of mechanical strain. (C) Single presynaptic pulse induced EPSC under different levels of mechanical strain. (D) The EPSC triggered by two successive presynaptic pulses under different levels of mechanical strain. (E) PPF results with respect to the applied strain for pulse with various pulse interval Δtpre. (F) PPF results with respect to the different Δtpre under different levels of applied strain (Photo Credit: Hyunseok Shim, University of Houston).

  • Fig. 2 The filtering characteristics of the fully rubbery synaptic transistor.

    (A) Schematic device structure and demonstration of multiple presynaptic pulses induced synaptic transistor responses. (B) Illustration of high-pass filtering behavior. (C) Measured EPSCs in response to 20 successive presynaptic pulses at 20 Hz without (0%) and with strains of 50%. (D) Illustration of EPSC induced by multiple presynaptic pulses and the definition of the gain (A20/A1). (E) The gain of the EPSCs (A20/A1) with respect to different pulse frequencies of the fully rubbery synaptic transistor without (0%) and with strains of 50%. (F) The peak current of the EPSC with respect to the number of pulses for the rubbery synaptic transistor without (0%) and with strains of 50%.

  • Fig. 3 The memory characteristics of the fully rubbery synaptic transistor.

    (A) Scheme of the SM, STM, and LTM. (B and C) Presynaptic pulses with variable pulse width and frequencies. (D) Memory characteristic of the full rubbery synaptic transistor under mechanical strains of 0 and 50% with the application of the 20 successive presynaptic pulses with a pulse width of 50 ms, a pulse frequency of 10 Hz, and an amplitude of −3 V. (E) The short-term weight change wn/w1 of the fully rubbery synaptic transistor corresponding to different pulse widths without (0%) and with 50% strain. (F) The long-term weight change ∆W/W0 of the fully rubbery synaptic transistor with respect to different pulse widths without (0%) and with 50% strain. (G) The wn/w1 of the fully rubbery synaptic transistor with respect to different pulse frequencies yet a fixed pulse width of 50 ms without (0%) and with 50% strain. (H) The ∆W/W0 of the fully rubbery synaptic transistor with respect to different pulse frequencies yet a fixed pulse width of 50 ms without (0%) and with 50% strain.

  • Fig. 4 Deformable neurologically integrated tactile sensory skin.

    (A) Schematic illustration of a biological somatic sensory system with mechanoreceptor and synapse-enabled skin. (B) Schematic exploded view (top) and optical image (bottom) of the neurologically integrated tactile sensory skin. (C) Schematic circuit diagram of the sensory skin from mechanoreceptors interfacing with the external stimulation to synaptic nerve that resulted in excitatory postsynaptic potential (EPSP) mapping. (D) Optical image of the sensory skin with applied tapping with objects in the pattern of U character. (E and F) The 5 by 5 EPSP mapping results from the stimulation in (D) for rubbery synaptic transistors before (E) and after (F) 50% strain. (G) Optical image of the sensory skin with applied tapping with objects in the pattern of H character. (H and I) The 5 by 5 EPSP mapping results from the stimulation in (G) for rubbery synaptic transistors before (H) and after (I) 50% strain (Photo Credit: Hyunseok Shim, University of Houston).

  • Fig. 5 Soft adaptive neurologically integrated robot.

    (A) Schematic illustration of the soft neurorobot and its programmed operation based on robotic memory decoded signals. (B) The EPSC after different numbers of tapping. (C) Programmed soft robot bending angle based on the short-term weight change (wn/w1). (D) Photograph of the soft neurorobot. (E) The corresponding EPSCs of the top, left, and right skins on the soft neurorobot during its adaptive locomotion for 50 s. (F) A sequence of images of the soft neurorobot locomotion adaptively based on the robotic memory signals in (E) (Photo Credit: Hyunseok Shim, University of Houston).

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/10/eaax4961/DC1

    Calculation of mobility and threshold voltage

    Fabrication of deformable neurologically integrated tactile sensory skin

    Design and fabrication of the soft pneumatic robot

    Fabrication of robotic skin

    Fig. S1. Optical image of fully rubbery electronic materials.

    Fig. S2. Frequency-dependent capacitance per unit area.

    Fig. S3. Schematic information of synaptic transistor.

    Fig. S4. Transfer curve and mobilities of the rubbery synaptic transistor.

    Fig. S5. EPSC results with respect to different pulse widths without (0%) and with 50% strain.

    Fig. S6. EPSC results triggered by two successive synaptic pulses with respect to different Δtpre without (0%) and with 50% strain.

    Fig. S7. EPSCs under mechanical strain along the channel width direction.

    Fig. S8. EPSCs induced by 20 successive presynaptic pulses with different frequencies without (0%) and with 50% strain.

    Fig. S9. Memory characteristics from 20 successive presynaptic pulses with different widths without (0%) and with 50% strain.

    Fig. S10. Memory characteristics with respect to the frequency of presynaptic pulses without (0%) and with 50% strain.

    Fig. S11. Schematic illustration of the major fabrication steps for the tactile sensory skin.

    Fig. S12. Neurologically integrated tactile sensory skin.

    Fig. S13. Resistance change of the pressure-sensitive rubber sheet with respect to the applied pressure.

    Fig. S14. Circuit diagram of the 5 by 5 arrayed synapse-implemented sensory skin.

    Fig. S15. The schematic geometry and cross-sectional image of the rubbery tactile sensory skin.

    Fig. S16. Measurement setup for EPSP mapping.

    Fig. S17. Design, fabrication, and optical image of soft pneumatic robot.

    Fig. S18. Synapse-implemented fully rubbery robotic skin.

    Fig. S19. Optical image of the synapse-enabled elastic robotic skin.

    Fig. S20. Schottky diode.

    Fig. S21. Triboelectric nanogenerators.

    Fig. S22. Input pulse and output EPSC during cyclic tapping.

    References (4749)

  • Supplementary Materials

    This PDF file includes:

    • Calculation of mobility and threshold voltage
    • Fabrication of deformable neurologically integrated tactile sensory skin
    • Design and fabrication of the soft pneumatic robot
    • Fabrication of robotic skin
    • Fig. S1. Optical image of fully rubbery electronic materials.
    • Fig. S2. Frequency-dependent capacitance per unit area.
    • Fig. S3. Schematic information of synaptic transistor.
    • Fig. S4. Transfer curve and mobilities of the rubbery synaptic transistor.
    • Fig. S5. EPSC results with respect to different pulse widths without (0%) and with 50% strain.
    • Fig. S6. EPSC results triggered by two successive synaptic pulses with respect to different Δtpre without (0%) and with 50% strain.
    • Fig. S7. EPSCs under mechanical strain along the channel width direction.
    • Fig. S8. EPSCs induced by 20 successive presynaptic pulses with different frequencies without (0%) and with 50% strain.
    • Fig. S9. Memory characteristics from 20 successive presynaptic pulses with different widths without (0%) and with 50% strain.
    • Fig. S10. Memory characteristics with respect to the frequency of presynaptic pulses without (0%) and with 50% strain.
    • Fig. S11. Schematic illustration of the major fabrication steps for the tactile sensory skin.
    • Fig. S12. Neurologically integrated tactile sensory skin.
    • Fig. S13. Resistance change of the pressure-sensitive rubber sheet with respect to the applied pressure.
    • Fig. S14. Circuit diagram of the 5 by 5 arrayed synapse-implemented sensory skin.
    • Fig. S15. The schematic geometry and cross-sectional image of the rubbery tactile sensory skin.
    • Fig. S16. Measurement setup for EPSP mapping.
    • Fig. S17. Design, fabrication, and optical image of soft pneumatic robot.
    • Fig. S18. Synapse-implemented fully rubbery robotic skin.
    • Fig. S19. Optical image of the synapse-enabled elastic robotic skin.
    • Fig. S20. Schottky diode.
    • Fig. S21. Triboelectric nanogenerators.
    • Fig. S22. Input pulse and output EPSC during cyclic tapping.
    • References (4749)

    Download PDF

    Files in this Data Supplement:

Stay Connected to Science Advances

Navigate This Article