System with liquid and solid media for target binding

A system comprising:

• a porous membrane support structure having a lateral dimension in direction of a lateral flow and a second dimension perpendicular to the lateral dimension,
• at least one primary support portion containing first binding compounds covalently bound to visual colloidal markers, capable of binding respective targets by forming first binding compound-target complexes with the respective targets,
• secondary support portions spaced and staggered in both the lateral dimension and in the second dimension such that no two secondary support regions are laterally aligned nor aligned in the second direction, each comprising second binding compounds covalently bound to the porous membrane support structure, the second binding compounds configured to bind either the targets or the first binding compound-target complexes, each second binding compound of the second binding compounds specific to a different target or different first binding compound-target complex of the respective targets, the second binding compounds being different from and non-competitive with the first binding compounds for said target,
• control regions spaced and staggered in both the lateral dimension and in the second dimension separate from and not overlapping with the secondary support portions and in a one-to-one correspondence with the secondary support portions such that every secondary support portion is adjacent to a corresponding control region such that no two control regions are laterally aligned nor aligned in the second direction, the control regions comprising third binding compounds configured to bind a respective first binding compound of the first binding compounds when unbound to the respective target, each control region configured to provide a control for the different targets at the secondary support portions, wherein second dimension placement of each control region has a same second dimension placement as its corresponding secondary support portion,
• a pH litmus indicator and a pH control strip that is separate from and not overlapping the pH litmus indicator, wherein the pH litmus indicator and the pH control strip are both located on the porous membrane support structure in the lateral dimension and second dimension downstream of the secondary support portions, wherein second dimension placement of the pH control strip has a same second dimension placement as the pH litmus indicator, and
• a liquid medium for lateral flow on the support structure, configured to allow preservation and activity of binding compounds.