Fig. 3
Reproduced with permission from [153] Copyright 2019 Royal Society of Chemistry
a Technological flow chart of the patterned STNNE. b FESEM image of the networked nanofibers. c FESEM image of the intersections of the nanofibers. d Optical photographs of the stretchable and transparent networked nanofibers film. Dispersion of PU/rGO/AgNPs in nanofibers. e Raman spectra of PU/GO/AgNPs nanofiber and PU/rGO/AgNPs nanofiber samples with a GO:AgNPs loading ratio of 1:1.25. f TEM images of nanofibers with diameters of ~ 290, ~ 484, and ~ 933 nm. g Schematics of the functional groups on GO, chemical structure of polyurethane, and negative surface charges of AgNPs. GO nanosheets can be hydrogen-bonded to the PU matrix by the functional moieties of the carboxyl and hydroxyl groups. h Optical transmittance-sheet resistance of the networked nanofibers for different types of nanofibers: rGO-coated PU, PU/rGO, PU/AgNPs, and PU/rGO/AgNPs nanofibers with that of copper nanowires, PEDOT: PSS/Zonyl/DMSO and graphene. i Stress–strain curves of PU/rGO and PU/rGO/AgNPs nanofibers. Evaluation of STNNEs under stretching conditions. j Resistance change (ΔR/R0) versus elongation of the PU/rGO and PU/rGO/AgNPs nanofiber electrodes on PDMS substrates. k Resistance change (ΔR/R0) versus low strain under tensile and compressive bending of STNNEs