Subclass 1/22: Suction or pumping devices for medical purposes; Devices for carrying-off, for treatment of, or for carrying-over, body-liquids; Drainage systems (catheters A61M 25/00 ; tube connectors, tube couplings, valves or branch units, specially adapted for medical use A61M 39/00 ; devices for taking samples of blood A61B 5/15 ;  saliva removers for dentists A61C 17/06 ; filters implantable into blood vessels A61F 2/01 ) Dialysis systems; Artificial kidneys; Blood oxygenators (semi-permeable membranes characterised by the material, manufacturing processes therefor B01D 71/00 ) with membranes sheet-like