To send data to the companion device several methods have been discussed. As we aim to provide this device to developing countries it is not guaranteed that access to internet will be accessible in all locations. Thus several methods have been tested to make the device usable by all  who need it. 

Possible solutions

Bluetooth Low Energy: BLE is one of the most common solutions which comes to mind when the internet is not available for transmitting data. As this system does not use a lot of energy and therefore saves battery we might use it in the final product depending on the flow rate required to send the data from the monitoring device to the companion device. However prototyping with BLE is hard to do hence we looked for another solution. 

ESP:  This method of communication is relatively simple to use and has a high flow rate. Very cheap. nearly 5 times as much data ram needed (regarding the issue talked about in the previous log). It can either be an access point or an emitter (which would cover both the monitoring device and the companion device).  In terms of size it is small enough to be fixed on the monitoring device.

Figures of the different emitters&receivers : 

ESP on the left BLE on the right.

These processes still need to be tested as the project evolves. For now we are concentrating on using two ESPs. Here is a schema of how the process will work: 

More information will be posted once further results are obtained.