Sensor systems for monitoring fluid intake indirectly and directly

Dehydration is a common and severe diagnosis especially among the elderly. Monitoring a healthy fluid intake is therefore vital. In this contribution five sensor approaches that detect fluid intake are presented and compared. Four of the sensor system use an indirect method by monitoring filling levels in a cup. The first concept is equipped with a conductivity based sensor which uses distinct electrodes at different heights for localizing the border between liquid and air. The second system exploits gravity to measure weight changes via hydrostatic pressure at the cup's bottom. In another design the beverage's weight is focused on a force sensor by a mechanism with a movable plate which is separated from the liquid by a flexible foil. The fourth concept uses shielded capacitive sensor detects the capacity inside the cup which is influenced by present media. The final approach monitors the actual fluid intake directly by means of flow measurements compactly integrated into a drinking straw. The implemented system uses a turbine flow meter with two Hall sensors in order to detect passing volume and the direction of the flow. Two electrodes distinguish between air and fluid in order to only monitor beverage intake. Finally, all five sensor designs are evaluated and compared with regard to accuracy, specific restrictions and conceptual realization. Although each concept has distinctive disadvantages they are suitable for detecting filling levels or fluid intake, respectively. A combination of direct and indirect methods to monitor drinking behavior is expected to help prevent dehydrations.