## 3 Results and Discussion
### Mechanical and Piezoresistive Characterization
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & \multicolumn{2}{c}{\(\sigma\) (S/m)} & \multicolumn{2}{c}{\(\rho\) (\(\Omega\)-m)} & \multicolumn{1}{c}{\(\mathbf{R_{0}}\)/\(\mathbf{R_{g}}\)} \\ \cline{2-6}
**Sample** & **0\%** & **8\%** & **0\%** & **8\%** & **8\%** \\ \hline
**D40** & \(3.49\times 10^{-5}\pm 8.48\times 10^{-6}\) & \(1.86\times 10^{-4}\pm 5.59\times 10^{-6}\) & \(3.03\times 10^{4}\pm 7.89\times 10^{3}\) & \(5.38\times 10^{5}\pm 1.67\times 10^{2}\) & \(6.12\pm 1.65\) \\
**D60** & \(5.01\times 10^{-6}\pm 1.77\times 10^{-6}\) & \(2.72\times 10^{-5}\pm 1.16\times 10^{-6}\) & \(2.14\times 10^{5}\pm 4.83\times 10^{4}\) & \(3.69\times 10^{4}\pm 2.83\times 10^{3}\) & \(6.33\pm 1.41\) \\
**D80** & N.A. & N.A. & N.A. & N.A. & N.A. \\
**G40** & \(3.00\times 10^{-5}\pm 3.42\times 10^{-6}\) & \(1.80\times 10^{-4}\pm 6.58\times 10^{-6}\) & \(2.52\times 10^{1}\pm 2.32\times 10^{3}\) & \(5.55\times 10^{1}\pm 2.02\times 10^{2}\) & \(4.95\pm 0.50\) \\
**G60** & \(1.76\times 10^{-5}\pm 9.25\times 10^{-7}\) & \(7.51\times 10^{-5}\pm 4.80\times 10^{-6}\) & \(5.70\times 10^{4}\pm 3.08\times 10^{3}\) & \(1.34\times 10^{4}\pm 9.59\times 10^{2}\) & \(4.66\pm 0.46\) \\
**G80** & \(1.32\times 10^{-5}\pm 3.67\times 10^{-7}\) & \(2.68\times 10^{-5}\pm 2.06\times 10^{-6}\) & \(7.60\times 10^{4}\pm 2.13\times 10^{3}\) & \(3.75\times 10^{4}\pm 3.07\times 10^{3}\) & \(2.21\pm 0.20\) \\
**S40** & \(1.17\times 10^{-5}\pm 5.67\times 10^{-7}\) & \(1.15\times 10^{-3}\pm 1.23\times 10^{-5}\) & \(8.53\times 10^{4}\pm 3.99\times 10^{3}\) & \(8.69\times 10^{4}\pm 9.25\times 10^{3}\) & \(106.80\pm 5.47\) \\
**S60** & \(4.86\times 10^{-6}\pm 9.32\times 10^{-7}\) & \(5.28\times 10^{-4}\pm 2.15\times 10^{-5}\) & \(2.12\times 10^{5}\pm 3.61\times 10^{4}\) & \(1.90\times 10^{2}\pm 8.01\times 10^{3}\) & \(117.29\pm 4.77\) \\
**S80** & \(1.50\times 10^{-6}\pm 1.34\times 10^{-7}\) & \(2.49\times 10^{-5}\pm 1.64\times 10^{-6}\) & \(6.74\times 10^{5}\pm 6.48\times 10^{4}\) & \(4.04\times 10^{4}\pm 2.64\times 10^{3}\) & \(18.7\pm 2.82\) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Electrical conductivity of TPU/GE composites as a function of porosity and internal morphology. Figure 8: Variation of gauge factor as a function of compression strain for the TPU/GE porous structures with: (**a**) Diamond, (**b**) Gyroid, and (**c**) Schwarz unit cells. The outstanding sensitivity of the SLS fabricated structures demonstrates that they can be used as piezoresistors in the detection of very small deformations (i.e., strain less than 5%). All the SLS fabricated TPU/GE structures were also characterized in terms of electromechanical cycling stability. The samples were submitted to 50 consecutive compressive cycles (at 8% of strain), as reported in Figure 9a for TPU/GE S40. In the cyclic compression process, both mechanical and electrical response of the sample were stable all over the experiment, demonstrating excellent stability and signal reversibility. Figure 9b summarizes the results of the electromechanical cycling tests for all porous structures. The resistance values at 8% strain reported as a function of time clearly demonstrate that regardless of porosity and geometry, after the very first compression cycles, all structures exhibited excellent stability and repeatability.