Both Faradaic and non-Faradaic processes can take place at an electrode. Thus, in a Faradaic process, after applying a constant current, the electrode charge, voltage and composition go to constant values. Instead, in a non-Faradaic (capacitive) process, charge is progressively stored.

## What is non faradaic region?

The portion of the current observed in an electrochemical system that cannot be attributed to any redox processes occurring at an electrode surface.

What do we measure in Electrochemical Impedance Spectroscopy?

Electrochemical Impedance Spectroscopy (EIS) is an electrochemical techniques to measure the impedance of a system in dependence of the AC potentials frequency.

Faradaic processes are defined as those which obey Faraday’s law, that is the amount of chem- ical reaction occurring is directly proportional to the amount of charge passed across the elec- trode boundary. When the system is in a steady-state the application of this definition is simple: all the current is faradaic.

The faradaic current is the current generated by the reduction or oxidation of some chemical substance at an electrode. The net faradaic current is the algebraic sum of all the faradaic currents flowing through an indicator electrode or working electrode.

### What does EIS measure?

EIS is a multifrequency AC electrochemical measurement technique. It measures the electrical resistance (impedance) of the metal/solution interface over a wide range of frequencies (from 1 mHz to 10 kHz).

Which is used for measurement of impedance?

An impedance analyzer is a type of electronic test equipment used to measure complex electrical impedance as a function of test frequency.

How do you plot impedance?

The impedance is plotted with log frequency on the X-axis and both the absolute values of the impedance (|Z|=Z0) and the phase-shift on the Y-axis.

## What are the types of supercapacitors?

Generally supercapacitors are classified in two categories commonly known as electric double layer capacitors (EDLCs) and Pseudocapacitors (PC). In EDLCs, electrical energy storage phenomenon is purely electrostatic in nature where polarized electrode active materials (usually carbon) and electrolyte ions.

## What are non-faradaic electrochemical impedance spectroscopy for sensing applications?

Citation: Faria RAD, Heneine LGD, Matencio T, et al. Faradaic and non-faradaic electrochemical impedance spectroscopy as transduction techniques for sensing applications. Int J Biosen Bioelectron. 2019;5 (1):29-31. DOI: 10.15406/ijbsbe

Why are there no reference electrodes in non-faradaic EIS?

Contrary to the faradaic EIS, the non-faradaic method does not demand the use of redox couples and, consequently, no reference electrode is necessary, because no DC potential is required 10 These features make this kind of sensors more amenable to miniaturization and to online/real-time applications.