Mitsubishi Electric Research Laboratories has developed a prototype of a drinking glass that will alert waiters that their patrons’ glasses are half empty and need to be refilled.

By using a combination of RFID and capacitance sensing technologies, researchers are proposing the commercialization of "wireless liquid level sensing glassware or iGlassware." The prototype developed in the lab incorporates a microchip and coil in the base of the glass that interact with a coating on the surface of the glass that determines how full it is. The liquid level is then transmitted to a base station.

• The coating conducts electricity and makes the glass behave like a capacitor, a device that accumulates and holds a charge of electricity.
• As the liquid is emptied, less of the glass is in contact with the liquid inside and the capacitance of the glass falls.
• The microchip in the base of the glass reads the change and uses the coil to signal the need for a refill.
• A code in the chip identifies the patron whose glass needs to be refilled and signals a mobile device carried by the waiter or a central display behind the bar.

Researchers propose that iGlassware should have the following characteristics:

• Extremely inexpensive
• Dishwasher safe
• Look and feel like glassware
• Support multiple glasses per table
• Ability to recognize a glass full of ice as being empty

For more information: http://www.merl.com/projects/iGlassware/

(Additional Source New Scientist)