Fig. 4: Mechanism underlying MEG operation.

a Schematic of the KPFM measurement apparatus. b, c KPFM images and corresponding histograms of the two regions shown in (a). d, e Zeta potentials and particle sizes of PDDA/NaAlg mixtures with different ratios. f, g KPFM image and corresponding histogram of pure PEDOT ribbon. h, i Log–log SAXS profiles of PDDA/NaAlg coacervate gel fibers with different ratios and corresponding R values (inset of h: a representative 2D SAXS pattern). j XRD patterns of fibers with different PDDA/NaAlg ratios. k Ionic conductivities of pure NaAlg and P5N20 coacervate gels. l MEG-associated properties of fiber-type MEGs with different PDDA/NaAlg ratios.