US company BACtrack make portable breathalyzers that are compatible with your smartphone, and the good news is that they ship to Spain!
The device transmits the results of your self-administered test to the app via bluetooth. The app the gives you more useful info about your result, such as how long it should take for your blood alcohol to get back down to 0. This aims to help you make smarter decisions after you’ve had a drink such as whether or not (and when) you should drive home.
BACtrack boasts that their gadgets are ‘police grade’, so they are as accurate as a roadside test. There are several options to choose from, including key-rings and mini versions.
Take a look at the video below, and if you think this might be the gadget for you, you can order one directly from BACtrack here.