The gel has molecules that bind to bacteria and activate a fluorescent dye.

Probe molecules, typically labeled with a fluorescent dye, are added to the array.

The maleimide functionality allows conjugation of the fluorescent dye to the sulfhydryl group of cysteine residues.

A similar redox-based assay has also been developed using the fluorescent dye, resazurin.

Assuming a pure fluorescent dye solution in an isotropic surrounding, the individual emitters are indistinguishable.