I meant the functionalized SAM is ElectroActive, it will give its own signal. A simple or SAM sensor may or may not be ElectroActive and what is its applicability? It should not show its activity in the range of specie to be sensed!!!!
Hi You may modify the electrode surface with anthraquinone for example which is redox active and you can use the electrode as pH sensor. Let me know if you have any questions.