Filter body, filter element, and filter assembly

A filter assembly comprising:

• a filter receptacle;
• a filter element received in the filter receptacle, wherein the filter element comprises
• a filter body, wherein the filter body comprises:
• a filter medium comprising filter layers arranged one over the other,
• wherein the filter layers each comprise at least one active material,
• wherein the at least one active material is the same in all of the filter layers,
• wherein the filter layers are configured to be flowed through serially in a through-flow direction of the filter body;
• sensor devices, each sensor device arranged between two of the filter layers neighboring each other, respectively, so that the sensor devices, in the through-flow direction of the filter body, are arranged one after another in order to determine a sorption capacity of the at least one active material of each filter layer over a service life of the filter body,
• wherein the sensor devices are attached to the filter receptacle,
• wherein the sensor devices are configured to penetrate into the filter body upon introduction of the filter element into the filter receptacle and are configured to be pulled out of the filter body upon removal of the filter element from the filter receptacle.