An immunosensor is a type of biosensor that combines a biological recognition mechanism with a transducer, which generates a measurable signal in response to changes in the concentration of a given biomolecule.

A SPR immunosensor consists of these parts: a light source, a prism, a transduction surface (usually gold film), a biomolecule (antibody or antigen), a flow system and a detector.

Immunosensors are biosensors based on interactions between an antibody and antigen on a transducer surface. Electrochemical immunosensors explore measurements of an electrical signal produced on an electrochemical transductor. This signal can be voltammetric, potentiometric, conductometric or impedimetric.

English Language Learners Definition of democracy. : a form of government in which people choose leaders by voting. : a country ruled by democracy. : an organization or situation in which everyone is treated equally and has equal rights. See the full definition for democracy in the English Language Learners Dictionary.

The United States is a representative democracy. This means that our government is elected by citizens. Here, citizens vote for their government officials. These officials represent the citizens’ ideas and concerns in government.

Immunosensors are probably the most reported biosensors; they are based on the binding properties of antibodies (Ab) toward a specific target, called an antigen (Ag). The most frequent Ab reported in biosensors are immunoglobulins G (IgG), with a typical molecular weight of 150 kDa and a mean size of 14 × 9 × 4 nm3.

Democracy is contrasted with communism primarily because the 20th-century communism of the U.S.S.R. was characterized by an authoritarian government, whereas the democracy of the 20th-century U.S. was characterized by a representative government.