Measurement of flow in infusion systems.

The development of three flow sensors for application in infusion systems is presented. One sensor measures the time of flight of an air bubble. A special design allows the bubble to be reused after every measuring cycle. The second flow sensor determines the pressure drop over a hydraulic bridge that is designed in analogy to an electrical Wheatstone bridge. The third sensor works using the phenomenon of heat transmission into the measuring liquid. Owing to their design, the sensors show different characteristics.