**2. Classification of films obtained by electrochemical polymerization method**

Polymerization is a reaction in which large molecules are created from many small monomers. Normally it is a process which must be controlled carefully under strict conditions. Recently electropolymerization method has been successfully used for the controllable preparation of films because of the advantages we referred in the introduction section. Three types of electrochemical methods are generally employed for the polymerization of different monomers: (1) a constant current (galvanostatic); (b) a constant potential (potentiostatic) and (3) a potential scanning/cycling or sweeping. Different types of polymer films were applied for the construction of sensors. They are classified as conductive and nonconductive films.
