The invention relates to a moisture detection device (40) for use with a device B for monitoring an access to a patient for an apparatus with which a liquid is supplied to a patient and/or a liquid is withdrawn from the patient via a hose line in particular for an extracorporeal blood treatment device A. The moisture detection device according to the invention is designed as a planar structure which is to be placed onto the skin of the patient and which has as moisture sensor an electrically conductive structure. The device is characterized in that the planar structure is a textile planar structure composed both of non conductive warp and weft threads and also of conductive warp and weft threads (50 60). The conductive and non conductive warp and weft threads are arranged in such a way that the electrically conductive structure is created. By spatial separation of the warp and weft threads a defined electrically conductive structure is generated in the fabric. An important advantage of using both conductive warp threads and also conductive weft threads is that an electrically conductive structure can be formed that has sections extending in different directions. With such a structure a moisture sensor can be created that has particularly high sensitivity. The electrically conductive structure is preferably closed with a terminal resistance R which is preferably not part of the moisture detection device (40) but of an attachment part for the device thereby simplifying production.
