Meet the BACtrack Skyn: a smart wearable device capable of measuring blood alcohol levels and sending them to your smartphone via Bluetooth. BACtrack Skyn passively tracks your alcohol consumption, so you won’t need to take a breath test every time.
The device pairs with your phone to alert you when you are approaching your limit. It can also notify a family member when you have had too much to drink. Here is how the device works:
BACtrack Skyn uses transdermal monitoring (via an electrochemical sensor) to track the ethanol molecules escaping through your skin. [uses a] proprietary algorithm and device calibration to convert the raw response reading to an estimated Blood Alcohol Content (BAC) reading.
More information is available here.