iOS application monitoring hydration levels with Empatica E3 wristband https://www.empatica.com/product-e4 . The wristband measures (apart from other data) skin conductivity. It is to some extent possible to extrapolate current hydration from this, which would be a great help for people over 50 - with age you lose sense to your hydration levels which can be fatal on sunny day.
In the end too many factors turned out to be affecting the readings, so medical use was unatainable. Therefore the project was enhanced with water intake tracking and function that used Estimote Beacon attached to your water bottle to alert you if you forgot to bring your watter with you. http://estimote.com/
Hydrate me was a project done in 2 days, that won 3rd place on Empatica Hackmed in Milano https://www.empatica.com/hackmed/ .
Thanks to Riccardo Arciulo and Olga Pustovalova for science & data help and wonderful guys from Empatica for fun weekend :)
Project was done with Objective-C and optimized for iOS 8. To use the Empatica API you need to obtain Estimote SDK key. https://www.empatica.com/connect/login.php