H. Schlicke, C.J. Schröter, M. Rebber, D. Battista, S. Kunze, T. Vossmeyer
University of Hamburg,
Keywords: freestanding, membrane, gold, nanoparticle, sensor, actuator, MEMS, NEMS
Summary:We present the focus of our current research, which is the investigation of the electronic and mechanical properties of freestanding gold nanoparticle (GNP) membranes, e.g. by micro bulge tests with atomic force microscopy (AFM) data acquisition and the design of devices suitable for probing their potential MEMS/NEMS applications. In a recent paper, our group presented a spin-coating based method for the facile fabrication of alkylenedithiol cross-linked GNP thin films with thicknesses ranging from 20 to 100 nm and their lift-off and transfer to 3d electrode microstructures. Placement on different microstructures featuring suitable electrode geometries enables various applications of the membranes as novel functional materials for sensors or actuators in micro- and nanoelectromechanical systems (MEMS/NEMS). Recently we reported the successful fabrication of a resistive ambient pressure sensor, employing a freestanding, 55 nm thick 1,6-hexanedithiol cross-linked GNP membrane as strain sensitive transducer. The membrane was deposited onto a microfabricated cavity with proximal metal electrodes. Sealing the cavity, the membrane was deflected by variations of the external pressure. The strain of the membrane and hence the pressure changes could be monitored by a simple readout of the membrane's resistance. Furthermore, we demonstrated the first application of the flexible and conductive freestanding GNP membranes as functional material for electrostatic actuators. In this case, 1,6-hexanedithiol cross-linked GNP membranes were deposited onto electrode microstructures in proximity to a back electrode. Deflections resulting from applied voltages were observed using AFM, confocal microscopy and interferometry. We also present current investigations aiming towards the fabrication of electrostatically driven resonators with resonance frequencies in the MHz range.  H. Schlicke, E. W. Leib, A. Petrov, J. H. Schröder, T. Vossmeyer, J. Phys. Chem. C 2014,118, 4386-4395.  H. Schlicke, J. H. Schröder, M. Trebbin, A. Petrov, M. Ijeh, H. Weller, T. Vossmeyer, Nanotechnology 2011, 22, 305303.  H. Schlicke, M. Rebber, S. Kunze, T. Vossmeyer, Nanoscale 2016, Advance Article, DOI: 10.1039/C5NR06937H.  H. Schlicke, D. Battista, S. Kunze, C. J. Schröter, M. Eich, T. Vossmeyer, ACS Appl. Mater. Interfaces 2015, 7, 15123-15128.