Figure 1

(a) Structure of a cross-linked PEDOT:PSS-based setup, consisting on three probing ITO stripes (ca. 1.49 mm width), ca. 2.75 mm apart, underneath the PEDOT:PSS film. Also shown is the electrolyte cubic container (lateral outside dimension of 1.7 cm, 1 cm high and wall thickness of about 2 mm prepared by 3D printing), which was glued on the PEDOT:PSS film at a nearly centred position. The Ag/AgCl reference electrode and the counter Pt electrode were immersed in the electrolyte, the bias leads were contacting the ITO stripes 1 and 3, while the probe lead (working electrode) contacted position 1, 2 or 3. (b) Variation of the EDL potential at position 1 when a + 0.5 V pulse (shown in red) is applied between contacts 1 and 3; (c) Variation of the EDL potential at position 3 when a + 0.5 V pulse followed by a + 0.2 V pulse are applied between contacts 1 and 3. The decrease of the EDL potential under a bias of + 0.2 V to 0.1 V evidences the scaling of the EDL potential change with the bias potential.