# Design of Three-Dimensional Electrical Impedance Tomography System for Rock Samples
## 7 Results
### Model Test  
To validate whether the system meets the design requirements, model testing is conducted as a primary step. In the field of geophysics, the utilization of impedance-capacitance network models, such as the Cole-Cole model [33; 34], has been proposed to simulate rock and ore specimens. Hence, in this testing phase, the Cole-Cole model's relevant theories are employed, and two sets of models (as depicted in Figures 7 and 8) are utilized to evaluate the measurement accuracy of the system.  
The testing results of model I are illustrated in Figure 9. The displayed charts in the App depict the graphs illustrating amplitude and phase when the potential electrode labeled as 1 is active. The complete measurement results for the model are presented in Table 2. From the obtained curves, it is evident that the magnitude curve exhibits a smooth increase that aligns closely with theoretical expectations, indicating accurate measurement of the magnitude values at each channel's corresponding current electrode position. The phase curve oscillates around 0 mrad, aligning closely with the expected phase near zero for a purely resistive model.  
\begin{table}
\begin{tabular}{c c c c c} \hline
**Parameters** & **FDM-EIT** & **EIT-40** & **KIT4** & **Our System** \\ \hline Publication & [11] & [14] & [32] & \\ Application Field & Human lung detection & Near-surface & Industrial & Rock and ore \\  & monitoring & analysis & analysis & analysis \\ Current Range & \(\pm\)20–200 \(\mu\)A & / & / & \(\pm\)104, \(\pm\)103, \(\pm\)100, \\  & & & & \(\pm\)10, \(\pm\)1 \(\mu\)A \\ Voltage Range & / & \(\pm\)10 V & \(\pm\)5, \(\pm\)10 V & \(\pm\)104, \(\pm\)103, \(\pm\)100, \\  & & & & \(\pm\)10, \(\pm\)1 mV \\ A/D Converter & 16 Bit & 24 Bit & 14 Bit & 32 Bit \\ Signal & Sinusoidal & Sinusoidal & Arbitrary & Sinusoidal \\ Power Supply & \(\pm\)1 V & 12 V & / & 5 V \\ Total of Electrodes & 16 & 40 & 96 & 384 \\  & & & & \\  & & & & \\  & & & & \\ \end{tabular}
\end{table}
Table 1: Parameter summary and comparison.  
Figure 8: Model II. The resistance values are uniformly set to 1000 \(\Omega\) and the capacitance values are uniformly set to 10 \(\upmu\)F. The black triangles represent current electrodes, with current electrode 1–10 selected in this test. Specifically, the current electrode labeled as 1 is located between R\({}_{0}\) and R\({}_{1}\). On the other hand, the white triangles represent potential electrodes, with potential electrode 1–6 chosen in this test. Specifically, the potential electrode labeled as 1 is positioned between R\({}_{10}\) and R\({}_{11}\).  
Figure 7: Model I. The resistance values are uniformly set to 1000 \(\Omega\). The black triangles represent current electrodes, with current electrode 1–30 selected in this test. Specifically, the current electrode labeled as 1 is located between R\({}_{0}\) and R\({}_{1}\). On the other hand, the white triangles represent potential electrodes, with potential electrode 1–6 chosen in this test. Specifically, the potential electrode labeled as 1 is positioned between R\({}_{30}\) and R\({}_{31}\).  
The testing results of model II are illustrated in Figure 10. The displayed charts in the App depict the graphs illustrating amplitude and phase when the potential electrode labeled as 1 is active. The complete measurement results for the model are presented in Table 3. The results demonstrate high accuracy in data acquisition, with a measurement error of less than 0.3% for resistance and within 1 mrad for phase measurements.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Electrode**} & **Measured** & **Theoretical** & \multirow{2}{*}{**Deviation**} & **Measured** & **Theoretical** & \multirow{2}{*}{**Deviation**} \\  & **Resistance** & **Resistance** & **(\%)** & **Phase** & **Phase** & **(mrad)** \\ \hline
1-1 & 1003.09 & 1000 & 0.31 & \(-\)0.0092 & 0 & \(-\)0.0092 \\
1-2 & 2002