Based on standard atomic force microscope cantilevers, the group of Prof. Gerber has developed microfabricated nanomechanical cantilever sensor arrays. Such sensors represent a powerful platform for a broad range of detection applications in physics, chemistry, material science, biology and medicine. For example, the sensor may respond with mechanical bending due to the absorption of molecules. Here we demonstrate the whole process, beginning with the cantilever functionalization with biomolecules or polymer layers, and ending with the actual measurements. We also highlight some of the applications in biochemistry and medicine. More recent developments comprise membrane surface stress sensors for breath characterization of cancer patients and an outlook to a commercial cantilever sensor instrument.