The device was supposed to be highly mobile, like a bracelet or wristband. This posed additional challenges, asi the mobile factor forced us to think about supplying the device with electricity and make it really small and portable. Since a lot of different pieces of technology suitable for this endeavour exist out there, some recherche was necessary for us to find a sensfully cheap, but practicable, small device that works well together with all other parts.
These components work well together - we tested them. The Bluefruit is especially recommendable, since it is very easy to use. For most use-cases, no programming will be necessary, since it gets detected as an ordinary HID (human interface device) by most computers and mobile phones who pair with it.