This paper presents an open platform for continuous monitoring of clinical signs through a smart and non-invasive wearable device. In order to accomplish a communication in proximity, the Near Field Communication wireless technology is used, providing a fast link between the device and the host, avoiding the pairing (as typically occurs for Bluetooth protocol) and limiting the power consumption. The Arduino ecosystem has been used for prototyping since it allows an easy and open integration of ad-hoc functionalities. The first prototype of the platform has been customized for human body temperature measurement, assuring a lifetime of the battery for at least 2 months. Moreover, the acquisition and related transmission of other kind of clinical signs could be easily implemented, making the platform cost-effective in mobile scenarios.