Wireless liquid level sensing for restaurant applications

Since restaurants often make much of their profits on drinks, it is critical for servers to offer refills in a timely fashion. We propose wireless liquid level sensing glassware to aid in this task. Specially instrumented glassware detects fluid levels via a high-resolution capacitance measurement. A coil embedded in the table inductively couples power to the glasses, and provides a path for data exchange. Our prototype glass uses a standard microprocessor and a small number of passive components, making it extremely inexpensive.