To simplify the formulation of the models and of their ensuing key equations and focus on the real issues at hand, the two following assumptions are made: (i) the partition coefficients between the enzymatic layer and the solutions on each of its sides are equal to unity for all considered species; (ii) diffusion coefficients of substrate and products in the solutions are set 𝐾 values. Yet, the overall validity of the approach developed hereafter will not be affected.