we have put in production a very tiny ESP8266 based low energy wifi module. It can be operated either connected to the USB on any RaspberryPI or run on rechargeable battery.
for more info please refer to our product page: http://www.qualtek.eu/index.php?option= ... &Itemid=75
or send us an email at firstname.lastname@example.org
The sales team of qualtek (Belgium)