## 5 Sensors
### Tissues Detection Sensor  
The sensor should detect different tissues from their optical properties. In the considered range of wavelengths, the sensor is tested by analyzing the response to four types of biological tissues (liver tissues, colon mucosa tissues, colon submuc tissues and colon serosa tissues) and the main goal was to use the gold and the aluminum nanostructures in order to detect the tissue over the nanoantenna [40]. As illustrated in Figure 16, the sensor structure is similar to those previously considered. However, the tissues are placed between the dielectric and the nanoantenna. Thus, the nanoantenna holes will be covered by those tissues instead of the dielectric. The tissue medium has a thickness of 200 nm, but only 150 nm is visible in the figure since the remainder is the nanoantenna thickness. The dielectric has also a thickness of 150 nm. Due to the model's wavelength range, the following simulations were done between 450 nm and 1200 nm. \begin{table}
\begin{tabular}{c c c c} \hline  & **23 °C to 100 °C** & **100 °C to 250 °C** & **250 °C to 300 °C** \\ \hline Peak (Gain) Sensibility per °C & \(1.752\times 10^{-3}\) & \(0.843\times 10^{-6}\) & \(8.536\times 10^{-3}\) \\ Wavelength Sensitivity nm/°C & 0 & 0.0381 & 0 \\ \hline \end{tabular}
\end{table} 
Table 1: Sensibility values for the peak. Figure 16: Topology of the simulated sensor structure. First, the gold made nanostructure is simulated considering the aforementioned tissues and its results are presented in Figure 17, where it is possible to verify that all the tissues responses are similar. It is noticeable that different tissues will produce different spectral peaks. In this case, it is possible to distinguish liver and three types of colon tissues. As expected, the difference among colon tissues is smaller than the difference between any colon tissue and the liver one. However, analyzing the spectral region near the peak, it is possible to better observe that even the colon tissues can be differentiated, as illustrated in Figure 18, with different wavelengths. The spectral variation values are presented In Tables 2 and 3, respectively for the peak and peak wavelength. There, it is possible to observe that the liver is easier to distinguish from any colon tissue, than the distinction among colon tissues. The same simulations were done using the aluminum nanoantenna, whose results are presented In Figure 19. There, although all the responses are very similar at higher wavelengths, the region around \(500\,\mathrm{nm}\), that is in focus in Figure 20, allows the detection of each tissue. Once again, the liver can be easily differentiated from the colon cells; however, it can be possible to distinguish similar tissues, as the colon ones. \begin{table}
\begin{tabular}{c c c c c} \hline  & **Liver** & **Colon Mucosa** & **Colon Submucosa** & **Colon Serosa** \\ \hline Liver & - & \(279.7\times 10^{-3}\) & \(318.7\times 10^{-3}\) & \(265.9\times 10^{-3}\) \\ Colon Mucosa & \(279.7\times 10^{-3}\) & - & \(39.0\times 10^{-3}\) & \(13.8\times 10^{-3}\) \\ Colon Submucosa & \(318.7\times 10^{-3}\) & \(39.0\times 10^{-3}\) & - & \(52.8\times 10^{-3}\) \\ Colon Serosa & \(265.9\times 10^{-3}\) & \(13.8\times 10^{-3}\) & \(52.8\times 10^{-3}\) & - \\ \hline \end{tabular}
\end{table} 
Table 2: Variation (sensibility) of the peak gain. Figure 17: Gold nanostructure response for different human body tissues. Figure 19: Aluminum nanostructure response for different human body tissues. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**[nm]** & **Liver** & **Colon Mucosa** & **Colon Submucosa** & **Colon Serosa** \\ \hline Liver & - & 6.02 & 6.02 & 9.03 \\ Colon Mucosa & 6.02 & - & 0 & 3.01 \\ Colon Submucosa & 6.02 & 0 & - & 3.01 \\ Colon Serosa & 9.03 & 3.01 & 3.01 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Variation (sensibility) of the peak wavelength. Figure 18: Gold nanostructure response for different human body tissues (zoomed).