The invention relates to a membrane. Partly permeable membranes often have holes or perforations having a specific diameter to allow substances having a smaller particle diameter to pass through, but to hold back substances having a larger particle diameter. Such membranes are subject to wear primarily at the holes, i.e. cracks form which grow through the membrane proceeding from a hole. Particularly in the case of micromechanical membranes having holes having a small diameter in the range of 1 μm or less, it is very difficult to detect the state of the membrane, in particular whether the latter has cracks. Membranes having cracks can then undesirably allow passage even of those particles which should actually be held back. In medical or hygienic applications, the function can then be impaired.