In order to measure the ultimate stress, strain, and toughness of the membranes, burst experiments were conducted on the DUV-treated samples. Figure shows an optical micrograph of the substrate with only few remains of the membrane M2 at the edge of the aperture after the burst test. The corresponding stress-strain curve is shown in Figure . For membrane M1, the corresponding data are presented in Figure (Supporting Information, Section S3). During the burst experiments, the pressure was increased until the membranes ruptured, defining the ultimate biaxial tensile stress and strain. The corresponding values of the two membranes were very similar (Table ). The mean values were ∼377 MPa and 0.68 %, respectively. Further, the membranes' toughness was determined as the area underneath the stress-strain curve, as indicated in Figure . The toughness values for both membranes are presented in Table .