A system for acquiring or measuring information relating to a state of dialysance, identifying a dialyzer apparatus, or identifying a membrane filter device during the operation of the dialyzer apparatus in a dialysis treatment of a patient. The dialyzer apparatus includes a housing having an internal volume portion and a membrane filter device arranged within the internal volume portion. The housing allows transmission of radiation. A sensor device connected to the housing of the dialyzer apparatus includes a signal receiving device designed to receive a radiation signal, from the housing, the signal characteristic of the state or the identification of the dialyzer apparatus or of the membrane filter unit of the dialyzer apparatus.