Because the charge transport in thin films comprised of ligand stabilized metal nanoparticles is governed by tunneling of electrons between neighboring nanoparticles, they respond highly sensitively to any change in interparticle distances, caused either by sorption-induced swelling or by stress-induced mechanical deformation. To gain more insight into the mechanisms governing the sensors' properties (e.g. sensitivity, response time, baseline-drift) we devote intense research efforts to characterize and control the charge transport properties as well as the structural and mechanical properties of these nanocomposites. Recently, we succeeded in preparing freestanding films of cross-linked gold nanoparticles and studied their mechanical properties using the micro bulge-test method. Potential applications of such AuNP-based membranes as components in sensors, actuators and MEMS elements are currently being studied in our lab.