Mechanical Properties. In order to characterize the mechanical properties of the hybrid membranes, AFM bulge tests were conducted, similar as described in previous studies. Figure shows exemplary bulge profiles of membrane M2. By reducing the pressure underneath the substrate, the membrane was bulged into the aperture. With increasing differential pressure, the deflection of the membrane increased up to ∼1.8 µm for the maximum differential pressure of 6 kPa. The biaxial modulus of the membranes was determined by fitting a spherical cap to the bulge profiles for each applied pressure setting, as described previously. By approximating the bulged membrane as part of a thin-walled spherical pressure vessel, the biaxial stress σ can be approximated using the following equation: