**5. Conclusions**

A low-cost and low power IoT Sensor Node with advanced measurement precision for e-health application that enables continuous patient monitoring has been presented. The sensor node is based on the e-health kit from Libelium-Cooking Hacks, which can perform various medical checks ranging from temperature and glucose level measurement to ECG tests. We have enhanced the key characteristics of the operations of the Raspberry PI single-board computer (model B/B+), which constitutes the basis for the aforementioned e-health kit, by improving the accuracy, through the incorporation of filtering algorithms to sensors' values within the implemented Sensor Controller. A flexible communication mechanism, which enables the definition of any type of sampling of sensors at the desired frequency, is also employed for successful data transmission and Sensor Node control. Furthermore, a power consumption minimization scheme has been developed by imposing suitable sleep intervals to the IoT Sensor Node (corresponding to the associated idle intervals between sensors' successive measurements) and periodically deactivating specific functions of the node (thus, expanding its battery life-time and autonomy from hours to days). A representative medical test-case was demonstrated and explored, elucidating the efficiency of the presented key features of the e-health IoT Sensor Node. These features, in combination with the successful testing/evaluation of most of its sensor functions, paves the way for further evolvement of the developed system to a low-cost e-health monitoring platform with capabilities comparable to high cost commercial counterparts. In this regard, future improvements encompass the utilization of the MQTT protocol that employs shorter TCP header and thus in turn will lead to even more lower power consumption and communication overhead for the IoT Sensor Node.

**Author Contributions:** Conceptualization, N.P., F.G. and M.B.; methodology, N.P., M.B. and F.G.; Software, N.P.; validation, N.P., M.B. and F.G.; project administration, M.B., writing—original draft preparation, N.P.; writing—review and editing, N.P., F.G. and M.B.; investigation, N.P., F.G. and M.B.; resources, F.G.

**Funding:** This research was partially funded by ELTAB project, gran<sup>t</sup> number 46543.

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