modern electrochemical instrumentation for non-faradic measurements: design and application

The design of the most of the commercial potentiostat rely on the faradaic current, and non-faradaic current are limited or omitted. such electrochemical (ec) instruments extensively limits application of ec measurement for non-redox compounds, which most of them cannot be measured. this is mainly due to submission dc part of the current in data processing result of redox reaction even in ac and square wave (sw) voltammetry. here, it is intended to present an overview for describing the new advanced methods for non-faradic measurements along with its applications. these include the extension of the ec methods employed to detect nonredox molecules, protein and cells in medical, environmental and industrial interests. also, our homemade electronic circuit for a potentiostat, software equipped with fft data processing, which include the basic theory of the non-faradic measurements in advanced ec methods. it will show that how non-faradaic measurements could be used for study of macroscopic processeces on the electrodes in solution interface. in fact, when an altering potential (ac or sw) excitation waveform was applied to the electrode, based on the electrical properties of compounds, non-faradic signal can be calculated and completely characterized. the electrode responses (which are frequency depended) represent the intrinsic properties of the system permittivity, impedance and capacitance. the selective or sensitive measurements based on capacitance, phase shift and admittance or impedance could be used for such compounds. some of the methods offer ec measurements without need of a reference electrode. this could be amenable to miniaturize ec systems for detection of bio/molecules in the gas phase, the fluidic solution (for example, blood sample) and bacterial contain, which is noninvasive.