## 3 Results and Discussion  
### Model Verification  
In this section, the geometrical features of the fabricated scaffold are evaluated according to the analysis of the captured images using Image J(r) Software, the elastic modulus of bulk gel and porous scaffolds are then examined and reported, and finally the results of the developed finite element model are presented and compared with the experimental measurements. Geometrical features of scaffolds were measured using captures images analyzed in Image J(r) Software. The average pore size was 0.39 \(\pm\) 0.03 mm and 0.47 \(\pm\) 0.06 mm in Z and X directions, respectively. The strand diameter and height of the scaffold were also measured as 0.58 \(\pm\) 0.06 mm and 2.63 \(\pm\) 0.12 mm in Z and X directions, respectively. To measure the penetration, the original CAD design and the printed scaffolds were compared in terms of the layer height. The penetration was calculated based on the difference in heights, giving a value of 510 \(\upmu\)m. Table 2 shows the parameters obtained from geometrical features of the fabricated scaffold and they were used in the simulation of the model, as input data. The compressive stress-strain response of the porous scaffolds and bulk alginate was used to calculate their corresponding elastic modulus. The elastic modulus of the bulk gel and alginate scaffold were calculated to be 42.3 \(\pm\) 1.58 KPa and 32.1 \(\pm\) 0.6 KPa, respectively. \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameters** & **Values (\(\upmu\)m)** \\ \hline \(N_{x}\) & 7 \\ \(N_{yx}\) & 15 \\ \(N_{yz}\) & 16 \\ \(N_{z}\) & 7 \\ \(D\) & 580 \\ \(\Delta_{0}\) & 510 \\ \(\Delta_{L}\) & 10 \\ \(P_{x}\) & 470 \\ \(P_{z}\) & 390 \\ \(E_{x}\) & 10 \\ \(E_{z}\) & 10 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Parameter values used in simulation by the finite element model. For finite element simulations, a mesh sensitivity analysis on the finite element model was performed by comparing the predicted elastic modulus using different mesh sizes, with the results shown in Figure 4. To do so, the mesh size was reduced until the change of the obtained results was negligible. Using this method, the mesh size value of 0.3 was obtained and used for all the simulations. Using the developed finite element model, the elastic modulus of the fabricated scaffold was predicted to be 28.76 KPa, which is in agreement with the experimentally measured one, i.e., 32.1 \(\pm\) 0.6 KPa. To further study the effectiveness of the model, more experiments were conducted by changing the penetration, pore size, and number of layers. For this, three sets of experiments were performed and for each set, one factor was subjected to changes and other parameters were taken the same as the ones listed in Table 2.  
For the first set, the penetration element was changed. Initially, the slice thickness, which was the subtraction of the 88% of the strand diameter and strand diameter value (i.e., 580 \(\upmu\)m), calculated as 70 \(\upmu\)m to have 510 \(\upmu\)m penetration. Then, the slice thickness was changed to reach 200 \(\upmu\)m penetration by trial and error. The model predicted 14.92 KPa for scaffolds with approximately 0.2 mm penetration within layers (the elastic modulus based on the experiment was 15.47 \(\pm\) 1.03 KPa). As mentioned, the model predicted 28.76 KPa as the elastic modulus of scaffolds with 510 \(\upmu\)m penetration which was in good agreement with experimental results (32.1 \(\pm\) 0.6 KPa), as shown in Figure 5.  
For the second set of experiments, the pore size of scaffolds was subjected to changes. Experimental results showed the elastic modulus of 22.43 \(\pm\) 0.49 KPa for scaffolds with \(P_{x}\) = 551 \(\upmu\)m and \(P_{z}\) = 487 \(\upmu\)m, while the model predicted 21.35 KPa (Figure 6). As it was mentioned, the elastic modulus of scaffolds fabricated based on parameters reported in Table 2 (\(P_{x}\) = 470 \(\upmu\)m and \(P_{z}\) = 390 \(\upmu\)m) was 32.1 \(\pm\) 0.6 KPa, while the model predicted 28.76 KPa.