Patent ID: 7854159

Claim:
A sensor for measuring the concentration of a component in a liquid, exhibiting a base body with a deformation body, a hollow chamber, wherein the hollow chamber on the one side is deformable through the deformation body and on the other side is rigidly closed, wherein the hollow chamber is filled with a swellable polymeric network which exhibits a volume phase transition at a certain concentration of a component in the liquid and through at least one opening in at least one of the rigid delimiting sides of the hollow chamber the liquid can have contact with the swellable polymeric network and wherein a mechano electrical transducer detects the deflection of the deformation body, characterized in that the sensor exhibits a servo device ( 8 ) contacting, working and exercising a mechanical force on the deformation body ( 3 ), wherein the servo device ( 8 ) is thus controllable by a control signal of a control member with a comparator unit ( 9 ) such that the deflection of the deformation body ( 3 ) is compensated by a force of the servo device ( 8 ) exerted on the deformation body ( 3 ) corresponding to balancing a displacement force of the swellable polymeric network ( 5 ) acting on the deformation body ( 3 ), and in that the corresponding control signal for the servo device ( 8 ) is the measurement value for the concentration of a component in the liquid ( 1 ).