Two students at a German university have designed a coaster that can tell servers when someone needs a refill. The device, developed by Matthias Hahnen and Robert Doerr of Saarland University, senses the weight of a beer mug placed on it and can signal to the bar when one is close to empty. Andreas Butz, a professor at the University of Munich who has been supervising the students, told the BBC the coaster can also sense if it is upside down and detect movement, making it useful for bar games. He suggested using it to vote on whether a karaoke singer should stand down. “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,” Butz said. © Copyright 2005 by United Press International

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