Quantum Dot Assay Schemes. Schematic illustration of the energy transfer schemes utilized in various types of QD assay paradigms. Each assay requires an energy input (electromagnetic, chemical, biochemical or electrical) that is transmitted to the QDs either directly or through an input intermediate. This energy modifies the electron behaviour within the QDs, which release the energy, either directly or through an output intermediate, in the form of emitted light or charge transfer (electrical current).