Electrostatically Actuated Membranes of Cross-Linked Gold Nanoparticles: Novel Concepts for Electromechanical Gas Sensors

We report the preparation of freestanding membranes of cross-linked gold nanoparticles (GNPs) and demonstrate their application as electromechanical sensors for volatile organic compounds (VOCs). First, we show that the fundamental vibrational mode frequency of electrostatically excited GNP-membranes shifts significantly when exposing them to solvent vapors. We attribute this effect mainly to the reduction of the membranes’ pre-stress. Second, the relief in pre-stress upon analyte sorption can also be detected via quasi-static actuation of the membranes. In this case, the increase of the deflection amplitudes at constant bias voltages can be measured as the sensor signal and correlated to the analyte’s concentration. Additionally, we propose a facile route to the fabrication of such hybrid MEMS/NEMS sensors using layer-by-layer spin-coating and contact printing