<unk><unk><unk>  Assay, or ELISA, is a biochemical technique used mainly in immunology to detect the presence of an antibody or an antigen in a sample. The ELISA has been used as a diagnostic tool in medicine and plant pathology, as well as a quality control check in various industries. In simple terms, in ELISA an unknown amount of antigen is affixed to a surface, and then a specific antibody is washed over the surface so that it can bind the antigen. This antibody is<unk>  to an<unk> , and in the final step a substance is added that the<unk>  can convert to some detectable signal. Thus in the case of flourescence ELISA, when light is shone upon the sample, any antigen/antibody complexes will flouresce so that the amount of antigen in the sample can be measured.
Performing an ELISA involves at least one antibody with specificity for a particular antigen. The sample with an unknown amount of antigen is immobilized on a solid support (usually a polystyrene microtiter plate) either non-specifically (via adsorption to the surface) or specifically (via capture by another antibody specific to the same antigen, in a "sandwich" ELISA). After the antigen is immobilized the detection antibody is added, forming a complex with the antigen.  The detection antibody can be covalently<unk>  to an<unk> , or can itself be detected by a secondary antibody which is<unk>  to an<unk>  through bioconjugation.  Between each step the plate is typically washed with a mild detergent solution to remove any proteins or antibodies that are not specifically bound.  After the final wash step the plate is developed by adding an<unk> tic substrate to produce a visible signal, which indicates the quantity of antigen in the sample. Older ELISAs utilize chromogenic substrates, though newer assays employ fluorogenic substrates with much higher sensitivity.
The ELISA Reverse method & device (ER m&d)  uses an innovative solid phase constituted of an<unk>  polystyrene rod with 4-12 protruding ogives; the entire device is suitable to be  introduced in a test tube containing the collected sample and the following steps (washing, incubation in conjugate and incubation in chromogenous) are easily carried out by immerging the ogives in microwells of standard microplates pre-filled with reagents, sealed and stored until their use. 
Important advantages:
-the rod has its ogives sensitized with different reagents, so to perform the simultaneous detection of different antibodies and different antigens for multi-target assays;
- the sample volume can be increased so to increase the test sensitivity in clinical (saliva, urine), food (bulk milk, pooled eggs) and environmental (water) samples;
- 1 ogive is not sensitized for highlighting the not-specific reactions of the sample;
- the use of  laboratory supplies for dispensing sample aliquots, washing solution and reagents in microwells is not required, so to allow the setting up of ready-to-use lab-kits and on-site kits.<unk>  ImmunoAssay (EIA) is a synonym for the ELISA.
Enzyme linked immunosorbent assay 
Direct fluorescent antibody
Enzyme assay
Heterophile antibody test
Hemagglutination assay
Polymerase chain reaction
Counterimmunoelectrophoresis
Nucleic acid hybridization