We have used the particle photon for building our prototype.

For processing the data it has powerful STM32F205 microcontroller is used for interfacing various sensors. Sleep modes are used frequently to increase the battery life of the wearable. It has a Broadcom BCM43438 module to provide wireless connectivity to the system and a version of it also supports both Bluetooth Low Energy and WiFi. Even though WiFi is power consuming (Redbear duo), we have used it to directly post the data to the cloud over WiFi in the prototype. The WiFi transmission is done in bursts to conserve battery.

It has an inbuilt chip antenna though since we used an aluminium enclosure for the electronics, A external PCB WIFI antenna was used in the system.
The future iterations would use a Nordic Semiconductors nRF52832 BLE Micro controller for its extremely low power consumption and low cost. Further due to the presence of NFC in the MCU, Pairing would be extremely simple even for parents without prior education.

The data can either be transferred through the parent’s smartphone if available or through a dedicated gateway device bundled along with the sensor which would send the data to the cloud over Mobile Networks. Even though the availability of mobile network is limited in very remote areas, Initiatives like the Google Project Loon is likely to expand connectivity to even remote locations around the world.