fig3

Figure 3. SEM images of the graphene-CNTs-TPU strain sensor at various stretching states during the first stretching/releasing cycle: A (i) and A (ii) 0%; B (i) and B (ii) 20%; C (i) and C (ii) 40% and back to D (i) and D (ii) 0 %; (E) Diagram of the stretching/releasing process. SEM: Scanning electron microscope; CNTs: carbon nanotubes; TPU: thermoplastic polyurethane.