A method and device for testing sensors to be applied on a patient's skin for detection of liquid or moisture are described, in particular for monitoring vascular access in an extracorporeal blood treatment, in which a patient's blood is carried away from the patient via an arterial line and is fed to the patient via a venous line. A method for producing sensors to be applied on a patient's skin for detection of liquid or moisture is also described. The method and device according to the present invention are based on the testing of one or more moisture sensors which are taken from current production. The method includes providing a large number of twists of the moisture sensor applied onto a torsion body, the mechanical stresses thus recreating the stresses that can occur in practice when the moisture sensor is applied or stuck onto the patient's skin or forearm.