Editing Assay (section)

===Signal amplification===
Depending on the nature of the signal amplification system assays may be of numerous types, to name a few:
#'''[[Enzyme assay]]''': Enzymes may be tested by their highly repeating activity on a large number of substrates when loss of a substrate or the making of a product may have a measurable attribute like color or [[absorbance]] at a particular wavelength or light or [[Electrochemiluminescence]] or electrical/redox activity.
#Light detection systems that may use amplification e.g. by a [[photodiode]] or a [[photomultiplier tube]] or a cooled [[charge-coupled device]].
#'''[[Radioisotope]]''' labeled substrates as used in [[radioimmunoassay]]s and equilibrium dialysis assays and can be detected by the amplification in [[Gamma counter]]s or [[X-ray plate]]s, or [[Photostimulated luminescence|phosphorimager]]
#'''[[Polymerase Chain Reaction]]''' Assays that amplify a DNA (or RNA) target rather than the signal
#'''Combination Methods''' Assays may utilize a combination of the above and other amplification methods to improve sensitivity. e.g. [[ELISA|Enzyme-linked immunoassay]] or EIA, [[enzyme linked immunosorbent assay]].