Fig. 4

Preparation of the composite hydrogel film and characterization of its conductive properties. a Schematic diagrams of the perfusion process of PEDOT:PSS-doped PAAm hydrogels. b The SEM photograph of PS inverse opal film. c The SEM photograph of composite hydrogel film. d The SEM photograph of the cross-section of PS inverse opal film. e The SEM photograph of the cross-section of composite hydrogel film. f Conductivity changes of different volume ratios of PEDOT:PSS / AAm. g Relative resistance changes within 9 days. Scale bars are 1 μm in (b)-(e)