Capacitive detection of filling levels in a cup

This contribution presents a smart cup that uses a capacitive sensor to detect its filling level in order to monitor fluid intake over time. Dehydration is frequently diagnosed in hospitals among the elderly and connected to numerous sequelae and deaths. An automated monitoring system that detects daily fluid intake of a patient could reduce the vulnerability to dehydration and therefore the vast expenses that are associated with this condition. The smart cup obtains the current filling level from a capacitive sensor consisting of multiple serially arranged discrete electrodes. It is placed on the outside surface of its wall and shielded against external disturbances. Sensor data is processed applying multiple signal filters and error correction methods. Drinking volume of beverages at room temperature is detected accurately and reliably but error rate rises for very cold or hot liquids. The prototype integrates all components in a compact way, is dishwasher-safe and can be charged inductively. Data is transmitted to a base station via Bluetooth Low Energy. This way, a monitoring device is presented which will help preventing dehydration of elderly people.