Here, we designed a new method for controlling feedback loops. Fig. depicts the network mo�f which consists of an equilibrium reac�on that can be perturbed by two opposing ac�va�on processes, one of which is immobilized on a surface. We used poly-L-lysine (PLL) to func�onalize the surface of microfluidic channels as it can bind strongly to glass and polydimethylsiloxane (PDMS), while providing free amine groups as the reac�ve layer (Fig. ). We first demonstrated that control over local ac�va�on allows for tuning the strength of the chemical feedback, and developed a mathema�cal model to support our findings. We then created polyelectrolyte mul�layers (PEMs) to change the capacity, and thereby the rate of the deprotona�on of the immobilized lysine residues. Finally, we demonstrate that the high control over the s�muli-response curves of PEM surfaces allows for encoding read and write opera�ons.