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Accurate theoretical results for interdigitated array of electrodes (IDAE) in semi-infinite cells can be found in the literature. However, these results are not always applicable when using finite cells. In this study, theoretical expressions for IDAE in a finite geometry cell are presented. At known current density, transient and steady state concentration profiles were obtained as well as the response time to a current step. Concerning the diffusion limited current, a lower bound was derived from the concentration profile and an upper bound was obtained from the limiting current of the semi-infinite case. The lower bound, which is valid when Kirchhoff's current law applies to the unit cell, can be useful to ensure a minimum current level during the design of the electrochemical cell. Finally, a criterion was developed defining when the behaviors of finite and semi-infinite cells are comparable. This allows to obtain higher current levels in finite cells, approaching that of the semiinfinite case. Examples with simulations were performed in order to illustrate and validate the theoretical results.required. Many authors have used numerical simulations to understand this working principle [4][5][6][7]. Also theoretical results are available [7][8][9]. The most significant of these results was obtained by Aoki [8,9], where exact expressions for the current-potential curves and limiting current in steady state were obtained for reversible and irreversible electrode reactions. Later, Morf and colleagues [7] did a theoretical revision of Aoki's results for the case of reversible electrode reactions with internal/external counter electrode.All of the results previously mentioned consider that the IDAE is subject to semi-infinite geometry, which means that the ratio between the 'height of the cell' and the center-to-center 'separation of the electrodes' is very large. This is not always true, as one can see in the case of some microfluidic devices where 'channel height' and 'electrodes separation' are of comparable size [10][11][12][13], especially when using low cost fabrication techniques or materials. Soft lithography and the use of transparency sheet masks are examples of simple and inexpensive techniques commonly used for fabricating microfluidic devices [14,15]. When using soft lithography, the channel height of microfluidic devices is determined by the thickness of the photoresist mold, which can vary in between 1 µm-200 µm [14]. When using photolithography and transparency sheet masks, the electrodes are constrained by the resolution of the transparency sheet mask, which can generate features between 20 µm-50 µm when using a printer operating at 3380 dpi-5080 dpi [14,15]. Therefore, the ratio between the 'height of the cell' and the center-to-center 'separation of the electrodes' obtained using these techniques is clearly finite and may vary between ∼ 0.01 − 10.Electrochemical applications [12,13,[16][17][18][19][20][21] and research through simulations [22][23][24][25] have been reported for IDAE in continuous ...