To better understand the influence of different HMs on D value we have applied chronoamperometry (CA) tests, first focusing on CS coatings, as their electric affinity allows for a superior increase in electron transfer kinetics, see Fig. . These experiments were first performed on flat screen-printed carbon electrodes (SPCEs) and hydrogel-coated SPCEs. It was assumed that for flat SPCE, the EASA is equal to its geometric surface area. The theoretical background and the obtained results are presented in the SI file, section S5, where Cottrell's and Berzins-Delahay equations were utilized to estimate the diffusion of Fe(CN)6 3-/4-through the CS HM, as eq. ( ) .