Research ArticleMATERIALS SCIENCE

Stretchable self-healable semiconducting polymer film for active-matrix strain-sensing array

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Science Advances  08 Nov 2019:
Vol. 5, no. 11, eaav3097
DOI: 10.1126/sciadv.aav3097
  • Fig. 1 Design and characterizations of strain-sensitive, stretchable, and self-healable semiconducting film.

    (A) Chemical structure of DPP semiconducting polymer, PDMS, and PDCA moiety introduced in both polymer backbones as dynamic bonding sites through metal-ligand interaction. Structure of the [Fe(HPDCA)2]+ moiety that is reversible dynamic bonds by force. (B) Schematic illustration of DPP and PDMS dynamically cross-linked through Fe(III)-PDCA complexation. (C) STEM dark-field and STEM-EDS elemental mapping of the DPP-TVT-PDCA (1):PDMS-PDCA-Fe (5) blend film. (D) Field-effect mobilities of the blend film organic thin-film transistors (OTFTs) (source and drain electrode: Au, 40 mn; dielectric layer: SiO2, 300 nm; gate electrode: highly doped silicon substrate) as a function of blending-weight ratio (semiconductor:elastomer). (E) Strain cyclic testing of the blend film (1:5). (F) Plot of dichroic ratio (α) of 1:5 blend film as a function of strain. (G) Relative degree of crystallinity (rDoC) calculated from (200) peak for both “parallel” and “perpendicular” directions to x-ray beam line. (H) Proposed mechanism for reinforcement of stretchability in blend film via metal-ligand dynamic bonding based on analyzed information.

  • Fig. 2 Strain-sensitive property of self-healable semiconducting film.

    (A) Schematic illustration for sequential fabrication procedures of the OTFT with stretchable self-healable semiconducting film (200 nm) using transfer-printing assembly. (B) AFM height images for pristine and stretched (100%) semiconducting films. Scale bars, 1 μm. (C) Transfer curves of OTFTs as a function of strain applied to semiconducting film along the tensile stretching direction and (D) GFs extracted from on-current of OTFTs. (E) Field-effect mobilities on strain and after releasing strain measured for the same device. (F) Field-effect motility as a function of stretching cycle at different strains. (G) Schematics for fabrication methods of the self-healed semiconducting film that was cut by bending a partially cracked PDMS stamp and its OTFT. (H) Optical microscope (OM) images of damaged semiconducting film through self-healing process and (I) self-healed film. Inset: Corresponding dark-field OM images. (J) Transfer curves and (K) field-effect mobility of pristine and autonomously healed OTFTs. R.T., room temperature.

  • Fig. 3 Characterizations of stretchable active-matrix transistor sensor array.

    (A) In situ measurement of resistance of Au/SEBS stretchable interconnect during 10 stretching cycles at different strains (50, 70, and 100%). Inset: Photographs of Au/SEBS interconnect at 0% (left) and 100% (right) strain. (B) Resistance change of Au/SEBS stretchable interconnect as a function of stretching cycle at 0 and 50% strain. (C) OM images of pristine (0% strain, upper left), stretched (100% strain, upper right), released (0% strain, lower right), and stretched (100% strain; 100 cycles, lower left) Au/SEBS stretchable interconnect. (D) Architecture and (E) photograph of a fully stretchable 5 × 5 active-matrix transistor strain sensor array fabricated via our developed strain-sensitive, stretchable, and self-healable semiconducting film. Scale bar, 5 mm. (F) Mapping and (G) statistical distribution of the field-effect mobility in our stretchable active-matrix transistor array. (H) Transfer curves and (I) normalized on-current of fully stretchable transistor in active-matrix array as a function of strain. Photo credits: Jin Young Oh, Department of Chemical Engineering, Kyung Hee University and Donghee Son, Biomedical Research Institute, Korea Institute of Science and Technology. SQRT, square root.

  • Fig. 4 Strain-sensitive stretchable active-matrix transistor array as skin-like stretchable strain sensor.

    (A) Transfer curves of the stretchable active-matrix transistor array as a function of drain voltage with four different drain/source voltages. (B) Photograph of the stretchable active-matrix transistor array under artificial sweat and (C) on- and off-currents of the stretchable active-matrix transistor array as a function of time. (D) Photograph of stretched active-matrix transistor array by poking with a plastic bar and (E) normalized on-current of the poked active-matrix transitory array. (F) Simulation result of strain applied by poking to the stretchable active-matrix array. Photo credits: Jin Young Oh, Department of Chemical Engineering, Kyung Hee University.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/11/eaav3097/DC1

    Fig. S1. Transfer curves of OTFTs.

    Fig. S2. Strain and stress curves of a blend film.

    Fig. S3. Poisson’s ratio of blend film.

    Fig. S4. Rheology analysis of the blend film as a function of frequency.

    Fig. S5. Rheology study of blend film as a function of temperature.

    Fig. S6. Differential scanning calorimetry curves of the blended film.

    Fig. S7. Stress-relaxation result of the blend film.

    Fig. S8. Recovery test of an elongated blend film.

    Fig. S9. TEM images of blend film as a function of blend ratio (semiconductor:elastomer).

    Fig. S10. Polarized UV-vis spectra.

    Fig. S11. Grazing-incidence wide-angle x-ray scattering patterns.

    Fig. S12. Grazing-incidence wide-angle x-ray scattering patterns.

    Fig. S13. Output and transfer curves of OTFT.

    Fig. S14. Stretching test of blend film.

    Fig. S15. Durability test of blend film on strain.

    Fig. S16. Strain and stress curve of bulk blend film after self-healing.

    Fig. S17. Transfer curves of all pixels in the 5 × 5 fully stretchable active-matrix OTFT array.

    Fig. S18. Transfer curves of active-matrix sensory transistor and normalized on-current.

    Fig. S19. Simulation results of maximum principal strain (e1), intermediate principal strain (e2), and minimum principal strain (e3) applied by poking the stretchable active-matrix array.

    Fig. S20. Fabrication process of PDMS dielectric layer for a stretchable transistor.

    Table S1. On-currents of active-matrix transistor array for measurement of normalized on-current mapping of the poked transistor array.

  • Supplementary Materials

    This PDF file includes:

    • Fig. S1. Transfer curves of OTFTs.
    • Fig. S2. Strain and stress curves of a blend film.
    • Fig. S3. Poisson’s ratio of blend film.
    • Fig. S4. Rheology analysis of the blend film as a function of frequency.
    • Fig. S5. Rheology study of blend film as a function of temperature.
    • Fig. S6. Differential scanning calorimetry curves of the blended film.
    • Fig. S7. Stress-relaxation result of the blend film.
    • Fig. S8. Recovery test of an elongated blend film.
    • Fig. S9. TEM images of blend film as a function of blend ratio (semiconductor:elastomer).
    • Fig. S10. Polarized UV-vis spectra.
    • Fig. S11. Grazing-incidence wide-angle x-ray scattering patterns.
    • Fig. S12. Grazing-incidence wide-angle x-ray scattering patterns.
    • Fig. S13. Output and transfer curves of OTFT.
    • Fig. S14. Stretching test of blend film.
    • Fig. S15. Durability test of blend film on strain.
    • Fig. S16. Strain and stress curve of bulk blend film after self-healing.
    • Fig. S17. Transfer curves of all pixels in the 5 × 5 fully stretchable active-matrix OTFT array.
    • Fig. S18. Transfer curves of active-matrix sensory transistor and normalized on-current.
    • Fig. S19. Simulation results of maximum principal strain (e1), intermediate principal strain (e2), and minimum principal strain (e3) applied by poking the stretchable active-matrix array.
    • Fig. S20. Fabrication process of PDMS dielectric layer for a stretchable transistor.
    • Table S1. On-currents of active-matrix transistor array for measurement of normalized on-current mapping of the poked transistor array.

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