# Autonomous Active Tag Using Energy Harvesting Strategies
## 5 Conclusions  
Autonomous active tags powered by a supercapacitor and solar and mechanical energy harvesting modules, capable of working independently for storing, transmitting and receiving information are viable for one application made from a project with a company. Consequently, this can be extrapolated to other applications, such as those related to V2I or smart houses. The tag has been tested in an outdoor scenario that fits our purposes and, given the results, we conclude that some parameters depend on the application, which are related to the different modes in which the transceiver, the microcontroller and the EEPROM can operate, and to the energy requirements that are basically based on a solar panel and supercapacitor. In addition, the use of a supercapacitor instead of a battery gives the tag a longer independent life.  
There is a great uncertainty in the amount of energy that is available in every moment as this energy depends on external factors as the sun or the cars. So, the different modules and the integration of them have been developed to work in the best possible way to obtain the larger quantity of energy and to use it to the tag has a greater autonomy.  
As has been said before, possible applications are not only roads and traffic signs but every environmental situation, such as the roof or a window of a house, or even a car. In an environmental situation, there are such variables as the temperature that can be saved to keep a record of the variations. Perhaps this information could be sent to another device in the communication range or to a reader that comes for the data. It could be the same inside a house, to monitor the temperature of different rooms, or to automatically control and monitor some elements like the air conditioning, the doors or even electrical appliances. All these are examples of what is now known as an IoT (Internet of Things) node. However, in our case, it is not necessary to plug it into the node to get power or change the battery when it is depleted.  
On the other hand, scenarios where there is a heavy load would be difficult to support, even with a great supercapacitor.  
As there is no other tag with the features and functions presented in this work, we consider that this solution is competitive and affordable for this application. The autonomy is defined, a parameter that other studies do not usually contemplate, and which we consider to be an important value to characterize the system, improve it and really know that it is autonomous. The integration of the different techniques is a good way to improve the functionality and scope of this work for a real environment.  
**Author Contributions:** Conceptualization, A.C., S.R., and A.A.; methodology, A.C. and S.R.; software, A.A. and S.R.; validation, A.C.; formal analysis, A.C. and S.R.; investigation, A.C. and S.R.; resources, A.A.; data curation, A.C. and S.R.; writing--original draft preparation, A.C.; writing--review and editing, A.A.; visualization, A.C.; supervision, A.A.; project administration, A.A.; funding acquisition, A.A. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was partially funded by the Spanish Ministry of Science and Innovation, under CDTI program (ITAGs Project).  
**Acknowledgments:** The authors also want to thank [PERSON] from B105 Electronic Systems Lab for his comments, which greatly improved the manuscript.  
**Conflicts of Interest:** The authors declare no conflict of interest.