Today Arduino has designed and released several different models and form factors. Including more advanced wifi and Bluetooth connected models.
AFRL and NextFlex choose Arduino primarily because it’s open-source and well documented, along with a vast community. Their innovation is both in the flexible substrate that the circuit is printed on, as well as the manufacturing processes used to build a circuit on it. While that substrate, and the traces printed on it, are flexible, the actual components appear to be traditional rigid SMDs.
Of course, the US Military is interested in this development for the same reasons you should be: It changes the game again, it expands the use cases for Arduino into the wearable market. For Military uses it could be on uniforms or other flexible garments that might need some black-ops tech! This is a proof concept showing the manufacturing process is practical, which means you might soon have a flexible Arduino in your own hands.
References:
[AFRL, NextFlex leverage open-source community to create flexible circuit system] – http://www.wpafb.af.mil/News/Article-Display/Article/1431533/afrl-nextflex-leverage-open-source-community-to-create-flexible-circuit-system/