Figure 2. Characterizations of the PM-PDMS / Au electrode and ionogel. a) Optical images of the MM i-skin device (the inset shows the SEM images of the full-field and local zoom-in papillary gold electrodes). b-c) Cross-sectional SEM image of the PM-PDMS film at different magnifications (the inset t illustrates the height and width size distribution of the PM-PDMS film bump). d) Schematic diagram of the internal crosslinking network and chemical structure of PVDF-HFP-based ionogel. e) Optical images of the ionogel (the inset displays the SEM images of the groove microstructure prepared by sandpaper template method). f) EDS elemental mapping of ionogel. g) X-ray diffraction patterns of PVDF-HFP and [EMIM]DCA ionogel loaded with different amounts of ionic liquids. h-i) Fourier infrared spectrum and Raman spectroscopy of PVDF-HFP-based ionogel loaded with different kinds of ionic liquids.