Blood treatment device comprising a functional unit for carrying out the blood treatment and method for monitoring the functionality and/or the operating state of the functional unit

A blood treatment device comprising:

• an attachment unit for attaching a functional unit intended for single use for carrying out a blood treatment;
• and
• a monitoring unit for monitoring the operability and/or the operating state of the functional unit,
• wherein
• the attachment unit comprises a top cover, a bottom contact surface, and an attachment component between the top cover and the bottom contact surface, the attachment unit being configured to house a functional unit such that, when the functional unit is housed in the attachment unit, a bottom surface of the functional unit rests on the bottom contact surface of the attachment unit;
• the monitoring unit comprises at least one light transmitter and at least one light receiver that are arranged in or on the top cover and directed downwardly such that light emitted by the at least one light transmitter falls on the top of the functional unit when the functional unit is disposed in the attachment unit, and light reflected from a part of the functional unit or a part of the attachment unit is reflected to the light receiver, and the monitoring unit comprises a calculation and evaluation unit that is configured such that conclusions can be drawn as to a defective state and/or a certain operating state of the functional unit when a functional unit is disposed in the attachment unit, based on the intensity of the light falling on the functional unit and of the light reflected from a part of the functional unit or a part of the attachment unit;
• the top cover of the attachment unit is attached to the attachment unit so as to be movable between an open position and a closed position;
• and
• the attachment unit comprises a suction unit for creating a vacuum at the bottom contact surface, so that a functional unit can be attached to the bottom contact surface by way of suction power.