Abstract
In this study, we investigate the mechanical properties of freestanding membranes made of graphene oxide (GO), titania nanorods (TNRs), and silk fibroin (SF) and demonstrate their application as electrostatically driven actuators. Using a stamping process, the membranes are transferred onto substrates with circular apertures or square cavities measuring ∼80 to 245 μm in diameter or edge length, respectively. Afterwards the membranes are exposed to deep-ultraviolet (DUV) radiation in order to photocatalytically convert GO to reduced graphene oxide (rGO). Microbulge tests combined with atomic force microscopy (AFM) measurements reveal enhanced mechanical stability after the DUV treatment, as indicated by an increase of Young’s modulus from ∼22 to ∼35 GPa. The toughness of the DUV-treated membranes is up to ∼1.25 MJm-3, while their ultimate biaxial tensile stress and strain are in the range of ∼377 MPa and ∼0.68 %, respectively. Further, by applying voltages of up to ±40 V the membranes are electrostatically actuated and deflected by up to ∼1.7 μm, as determined via in situ AFM measurements. A simple electrostatic model is presented that describes the deflection of the membrane as a function of the applied voltage very well.
Supplementary materials
Title
Supporting Information
Description
Analysis of particles used for film fabrication, atomic force microscopy scans for thickness determination
of thin films, additional data regarding bulge tests on freestanding membrane M1, derivation of
Equation 5 and further voltage-deflection data.
Actions