## 4 Conclusions  
The measuring device presented in this study offers many advantages over sensors described by the majority of other authors.  
We have designed a sensor to measure the concentration of sucrose in real-time based on SPR. The sensor is based on intensity interrogation; therefore, it is not necessary to extract a sample and measure the concentration in tanks, recipients, deposits, or any other container where the sucrose solution is. Compared with the sensors based on angle interrogation, we avoid the extraction of the sample from the container, so we know the exact place where we are measuring which does not occur when using the angle interrogation sensor.  
Both the silver and the aluminum-coated sensors are able to measure 95% of the reflectance, i.e., the outer signal is very high.  
Our sensor works with only one laser, only one photodiode, and only two optical fibers, for this reason, it only needs one hole in the upper side of the tank or container (if the tank has to be closed) for the solution we want to measure. As the device works with one only wavelength, periodical calibrations are unnecessary.  
In addition, it is capable of continually measuring concentrations of sucrose with very similar (or very different) refractive indexes which do not attack the optical fiber, or the structure used.  
The overall system is equipped with a visual and audible alarm which can be regulated to any low or high concentration of sucrose. Another specification is that the gauge is controlled by a PC capable of storing the data in the memory, printing them, or sending them in real-time by internet.  
Our sensor could be integrated with others capable of measuring concentrations of salt, acids, etc., and become part of an electronic language.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Chemical Sensors** & **Physical Sensors** & **Slow Response Time** & **Instant Response Time** \\ \hline
[5, 10] & [6, 7, 8, 9, 11, 13, 23, 24, 25, 26, 27, 28] Ours & [2, 10] & [1, 3, 28]. Ours \\ \hline
**Raman spectroscopy** & **Optical fiber sensor** & **Resonance** & **With samples** & **Plasmonic sensor** \\ \hline
[6, 7] & [8, 11, 13, 26] & [9] & [10, 11] & [1, 3, 28], Ours \\ \hline
**High resolution** & **Low resolution** & **High sensitivity** & **Low sensitivity** & **Short dynamic range** & **Wide dynamic range** \\ \hline
[8, 27, 28], Ours & [1, 25] & [27, 28], Ours & [24, 25] & [13, 24, 28] & [26], Ours \\ \hline \hline \end{tabular}
\end{table}
Table 1: Summary table with the essential characteristics of the sensors studied.  
**Author Contributions:** Conceptualization, A.M.P. and F.P.-O.; methodology, J.M.S.; software, J.M.S. and O.R.; validation, A.M.P. and F.P.-O.; formal analysis, J.M.S.; investigation, A.M.P., F.P.-O., J.M.S. and O.R.; resources, A.M.P., F.P.-O., J.M.S. and O.R.; data curation, J.M.S. and O.R.; writing--original draft preparation, F.P.-O.; writing--review and editing, A.M.P., J.M.S. and O.R.; visualization, A.M.P., F.P.-O., J.M.S. and O.R.; supervision, A.M.P. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research received no external funding.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Not applicable.  
**Acknowledgments:** The authors wish to thank [PERSON], a native English speaker and expert in translations of scientific papers, for her assistance with the English version.  
**Conflicts of Interest:** The authors declare no conflict of interest.