You've had a drink. Your friends are trying to convince you that you're definitely still safe to drive them back home to embark on that Back to the Future marathon you've been discussing. Do you a) not risk it and get a taxi, or b) deploy your trusty portable breathalyser to reassure yourself if you're over the limit.
The answer should ALWAYS be 'A' - even small amounts of alcohol can effect your ability to drive.
That said, the DrinkMate is still a marvel of miniature gadgetry.
The invention of Washington-based Edge Tech Labs, this portable breathalyser functions by plugging into the brains of your Android smartphone via its mini-USB input. Housed within this key-chain genius is a semiconductor-based sensor: breathe into the DrinkMate's specially designed air inlet and wait a couple of seconds for the accompanying app to indicate your BAC (blood alcohol content).
Measuring just 4.7 by 1.5 centimetres, the DrinkMate claims to be the smallest breathalyser in the world (though this doesn't take into consideration the size of the smartphone you have to plug it into to work). Accurate to within 0.01 BAC percent, the DrinkMate is designed to be an exacting tool for combating drinking peer pressure - finishing arguments as to whether it's "time to go home" or convincing your friend that he definitely isn't in the right state to call his ex.
Currently undergoing Kickstarter funding, you can pick up a DrinkMate for around £16.
(Images: Kickstarter/Edge Tech Labs)