Now, for the practical part:

We have developed a custom wrist-mounted device, RF enabled, that integrates into a low-power Mesh network ( OpenThread ). All Bio data are sent to our server hosting a full stack application (backend/database and front end). This system is easily scalable so hundreds of companies can monitor the health status of hundreds of their employees. 

Overall Behavior and Hierarchy of the system:   

Each person is wearing a custom smart wristwatch that contains essentially two temperature sensors (on for the skin and one for the ambient temperature, one heart rate / oximetry sensor (oxygen level), and one dehydration sensor (that is still under development with our research team). Each of these devices is transmitting and listening data from the RF low-power network they are authenticated to, at regular intervals. The network is created by a set of routers that relay the sensor data to a gateway, which is a router connected to a board computer with an internet access. This RF mesh network protocol is the OpenThread implementation, for low-power, (relatively) high bandwidth and latency, and robustness. This Gateway, send data to our backend application, hosted online , with a by directional communication . That way, our server online can received and send data to each node. Finally we designed a frontend application (website) that can display all of these data and control the overall behavior of the system. Moreover, this system integrate user authentication, meaning that we can easily scale this system up, so that many different company can have their own sets of wristwatch/routers/gateway and access their data online, securely, as we are using the latest security technologies, both for the online server, the mesh network and the hardware. 

The breakdown of the project's components (and codes): 

• Wrist-mounted device (wristwatch), containing sensors and wireless chip for the mesh network communication, battery powered, with a firmware written in C. This system is custom made by our team, which concerns both the Printed Circuit Board (PCB) and the wristwatch bracelet (3D printed with hard and soft materials). 
• Mesh Router device (plugged to a wall socket) containing a wireless chip with a power amplifier (firmware written in C as well). This system is also custom made (PCB, and 3D printed case). 
• Mesh Gateway device with the same component as the Router above; it role is entirely different as It is the interface between our mesh network and the single board computer, with which they communicate via a serial connection (C programming). 
• Gateway device , which is a single board computer running a Node.js daemon program, which make the link between our full-stack application and the Mesh network (JavaScript). 
• Backend server application , Which consists into a REST API coupled with a Database. We used Node.js with Express and MongoDB. This application was written in JavaScript. 
• Frontend Application (hosted by the backend server) that uses the Angular framework (Typescript/ JavaScript). 
  The 6 above parts are 6 independent programs and physical devices (except for the frontend application and backend server that are run on online servers).