The in-plane, printed G-CAPode consists of a W-Cap which is represented by a printed CAPode with ion-sieving characteristics published and electrochemically characterized in detail elsewhere. In short, the WE of the CAPode consists of an Cmicro (sieving carbon) with an average pore size of 0.69 nm as well as a Cmeso electrode (omnisorbing carbon) with an average pore size of 3.1 nm. 1 M tetrabutylammonium tetrafluoroborate (TBABF4) in acetonitrile (ACN) was used as asymmetric electrolyte with different ion sizes (bulky cation TBA + ; ion diameter d(TBA + ) = 1.1 nm), small anion BF4 -, d(BF4 -) = 0.41 nm) to achieve the desired sieving effect of different ion sizes. The GE is printed with the same Cmeso suspension like the CE surrounding the interdigital structured W-Cap to ensure proximity to both WE and CE (Figure ). The geometrical electrode area of WE and CE is 9 and 15 mm 2 , respectively, resulting in a ratio of about 1:1.5 (similar WE:CE ratio like the structure (S1) presented in our former studies), the GE has a more than three times higher geometrical electrode area than CE (50 mm 2 ).