**7. Conclusions and Future Work**

In this work, we presented the design, implementation and expert evaluation of two smart devices used to promote healthy behaviors (i.e., healthy snacking and physical activity). We presented the technical details of the device implementation and software architecture based on a framework to develop smart device-based notifications.

The prototypes were evaluated by nine specialists in nutrition and physical activity from three countries (i.e., Spain, Mexico and Costa Rica). Results show that the system is well received by the experts, and that they will be willing to recommend the system to their friends, family or patients.

The system was evaluated applying a standard categorization for ergonomics in human-system interaction. The best ranked categories for this evaluation were comprehensibility, effectiveness and clarity. This leads us to think that the system will be usable, and it will provide a nice user experience. The worst ranked categories were suitability for learning (i.e., the system does not teach the user how to use it) and discriminability. The discriminability problem is mainly due to the use of a small graphic display in the prototype.

Furthermore, we observed that the degree of satisfaction in Mexico and Costa Rica are the same. However, evaluators from Spain are more reluctant about the system. According to the expert evaluators (eight out of nine), the system proposed in this paper would be useful to promote healthier behaviors in the system users. The only negative response believes that providing the notification is not sufficient, but also more control should be provided by the system.

In future work, we will improve the system based on the expert suggestions and evaluate it with families in their households, integrating the analysis of physical activity parameters to support the enrichment of adapted notifications provided by the system.

Furthermore, we will investigate how human activities are affected by this kind of smart device based notifications. Also, if users make responsible and proper use to achieve what smart devices pretend by adding new functionalities regarding persuasion and motivation focused on other domains of application, not only childhood obesity and overweight.

Although this research was prepared and executed carefully, it still has some limitations. First, the evaluation sample size (nine specialists in nutrition and physical activity) is reduced. This is due to the difficulty to personally work with specialists. Researchers considered applying an online survey to reach a larger sample; however, the final decision was to conduct personal interviews to focus the evaluation in the prototypes usefulness and its usability/ergonomics. Another limitation is that the evaluators are from different countries. Therefore, they might have different perspectives and points of view. However, the selection of three Spanish-speaking countries with cultural similitudes was a key factor to conduct the research as it is described in this paper.

**Acknowledgments:** This work was partially supported by CITIC at Universidad de Costa Rica, Grant No. 834-B8-165, by MICITT and CONICIT of the government of Costa Rica, and by the Plan Propio de Investigación from Castilla-La Mancha University.

**Author Contributions:** Gustavo López and Luis A. Guerrero defined the framework applied in this project. Gustavo López designed the evaluation instrument. Iván González designed the technical components of the smart devices. The evaluations were performed by Gustavo López and José A. Brenes (Costa Rica), Elitania Jimenez-Garcia (Mexico), Iván González, Jesús Fontecha and José Bravo (Spain). The work was also based in a previous work developed by Elitania Jimenez-Garcia, Jesús Fontecha and José Bravo.

**Conflicts of Interest:** The authors declare no conflict of interest.
