Common conducting polymers used in impedimetric biosensors in polypyrrole, polyaniline and polythiophene. Polypyrrole (PPy) has an advantage over other conducting polymers as it can be electropolymerised from an aqueous solution at neutral pH, whereas aniline is only soluble in acidic solutions and thiophene in organic solvents. Though thiophene is not water soluble, its derivatives can be, such as poly (3,4-ethylenedioxythiophene) (PEDOT). 107