## 3 Mechanism of Cyclic Voltammetry Transducer
When the applied voltage to the graphene electrode increases, the FE increases. As a result, the electron can jump from the electrode to the molecule due to being thermodynamically unfavorable where the process depends on the electron transfer rate, thanks to the electrochemical properties of graphene nanocomposites that make its electrodes very sensitive for different molecules with a very good electron mobility [86; 88]. During the cyclic voltammogram process, the potential is swept up to a maximum value (oxidation) and then back down (reduction) again, which leads to a constant potential rate over time. The analytical GOx could use this technique as a fourth generation of the glucose nano-biosensor [89]. When the oxidation starts at the graphene nanocomposites electrode, the current starts to ramp up until it reaches the maximum value while the oxidation peak is the key observation [88]. The oxidation peak is proportional to the concentration of the glucose. If the reduction starts, the overall voltage starts to decrease, as a result, the overall current starts to decline--where the reduction peak will be present. Oxidation and reduction peaks are the key concepts of the voltammetry experiment [84]. Different scan rates lead to different results [82; 89; 90; 91]. Figure 6A shows the CV potential waveform. At t = 0 to t = 1--the potential increases and the overall current increases (oxidation). At t = 1 to t = 2--the potential decreases and the overall current decreases (reduction). During the reversible process at a given point, the current is fully determined according to the voltage. The peak potentials (Epa, Epc) and peak currents (Ipa, Ipc) of the anode (where the oxidation happens) and cathode (where the reduction happens) are extremely important as CV parameters, which lead to more information about the data of the glucose oxidation and reduction [83]. Figure 6B shows the cyclic voltammogram (current vs. voltage), this is the way that the current and the potential changes--swep \begin{table}
\begin{tabular}{c c} \hline \hline
**Equation** & **Definition** \\ \hline \(I=\frac{dQ}{dt}\) & Current = the change rate of the negative charge (electron) per time unit in the CV cell \\ \(J=\frac{I}{\Lambda}\) & Current density = the current flow through the unit area \\ \(E=E^{*}-\frac{RT}{RT}\ln Qr\) & The Nerst and Butler equation = gives information about \\ \(E=\) Cell potential, \(E^{*}=\) Standard cell potential, \(Qr=\) Reaction & the applied potential that controls the concentration of \\ Quotient = oxidized species/reduced species, n = number of & the oxidation and reduction species at the electrode \\ electrons & surface and the rate of reaction \\ \(\frac{I}{\ln\Lambda}=K\left[Coe^{-\alpha\theta}-Cre^{(1-\alpha)\theta}\right]\) & Butler-Volmer equation = gives a good relation between \\ \(A=\) Electronic area, \(K=\) Heterogeneous Rate Constant, and & the current, potential, and concentration \\ \(\theta=\frac{nF[E-E^{*}]}{RT}\) & [PERSON]’s law = describes the diffusion of the reactance and \\ \(D\theta=\) Diffusion Coefficient of the reactance, \(x=\) the distance & product with respect to the distance from the electrode \\ from the electrode & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Basic equations of the CV cell. The mathematical models of the CV analysis could be investigated for more understanding [83; 87; 92; 93].