US Patent 9333281 Drainage pump unit

A drainage pump unit for aspirating body fluids by means of a suction pump has a suction pump arranged in a suction pump housing, wherein a fluid collection container can be secured releasably on the suction pump housing, and wherein a capacitive filling level sensor is arranged on the suction pump housing for detecting a filling level in the fluid collection container. The filling level sensor has at least two electrodes, which are arranged at a distance from each other and extend along a common path. A first of the electrodes is in one piece, and a second of the electrodes is segmented. This arrangement permits the production of inexpensive fluid collection containers while still ensuring a high degree of measurement accuracy.