But can I get my wife to wear the radio transmitter?
A beer mat that knows when a glass is nearly empty and automatically asks for a refill has been created by thirsty researchers in Germany. . .
The disc-shaped mat can be attached to a normal beer mat so that it still soaks up spilt liquid and displays an advertisement. But it also contains a pressure sensor and radio transmitter to alert bar staff of the need for a refill.
The device weighs 110 grams and costs $100 to make, but Butz and Schmitz think the weight and cost would shrink if the mat were to be mass-produced.
Link.