An intelligent beermat that alerts the bartender that your glass is empty could feature in pubs of the future.
Cheers, I'll have a refill.
Like an ordinary mat, it absorbs drips; but the gadget also has hidden sensors.
The device will detect the weight of the drink above it, working out how much is left before sending a signal to the bar for a refill.
The coaster can also tell which way up it is, and whether it's moving around. The creators think the mat could be used for voting in pub games.
This might be handy in a karaoke bar, for example, where the audience has to decide whether the performer should continue or stop.
"If they just raise their glass, that's a positive vote; if they raise their glass and flip over the beer mat, that's a negative vote," explained Professor Andreas Butz, at the University of Munich, Germany.
He supervised two students - Matthias Hahnen and Robert Doerr - as they developed their concept for an everyday object that could be enriched by computers.
Given the reputation of students, it was perhaps no surprise the pair - one is a product-design student, the other a computer scientist - had the idea of a beermat containing embedded circuitry.
"It has two sensors - one that can measure the weight of a glass that's resting on it, and a gravity sensor so it can know whether it's flipped upside down," explained Professor Butz.
A traditional mat is positioned on the top of a waterproof casing
"You can distinguish a lot of weight as a full glass, a little weight as an empty glass - no weight means somebody has lifted their glass."
When drinks are low, a blinking light at the bar could let the waiter know to check that table for a top-up.
Because the mat can also sense being picked up and flapped around, customers can signal an order - with the urgency judged by the speed it is moved.
Another feature is that drinkers can say how many drinks they would like to order by stacking of a number of mats in one hand.
The final design consists of a flat, cylindrical body, which contains the electronics; and a rectangular recess on the top that holds a conventional cardboard beermat.
The present cost to make a single mat is around US$100 (£60), but this would be around 10 times cheaper if they went into mass production, say the students who work out of Saarland University.
Some cultures have developed bar games using beermats. Could these new mats bring another dimension to this play?
Images courtesy of Andreas Butz and Michael Schmitz; technical drawings courtesy of Matthias Hahnen and Robert Doerr