A pixel-by-pixel, digitally-addressable, pixelated, precursor, fluid-assay, active-matrix micro-structure including plural pixels formed on a substrate, wherein each pixel includes (a) at least one non-functionalized, digitally-addressable assay sensor, and (b), disposed operatively adjacent this sensor, digitally-addressable and energizable electromagnetic field-creating structure which is selectively energizable to create, in the vicinity of the at least one assay sensor, an ambient electromagnetic field environment which is structured to assist in functionalizing, as a possession on said at least one assay sensor, at least one digitally-addressable assay site which will display an affinity for a selected fluid-assay material.