▎ 摘　　要

This letter reports an experimental study of an electrothermal actuator made from an ultra-large graphene-based bilayer thin film with a diameter to thickness aspect ratio of similar to 10000. Suspended thin films consisting of multilayer graphene and 350-500 nm-thick Poly(methyl methacrylate) have been transferred over circular cavities with a diameter of 3.5 mm. The use of bilayer materials with different mechanical and thermal properties results in thin film structures that can be induced to vibrate mechanically under the electrothermal transduction mechanism. The dynamic response of the bilayer has been investigated electrothermally by driving the structures with a combination of alternating current and direct current actuation voltages (V-ac and V-dc) and characterizing their resonant frequencies. It has been found that the bilayer thin film structure behaves as a membrane. In addition, the actuation configurations affect not only the amplitude of vibration but also the tuning of the resonant frequency of the vibrating membranes. The existence of Joule heating-induced tension lowers the mechanical stiffness of the membrane and hence shifts the resonant frequency downwards by-108187ppm. A resonant frequency of 3.26kHz with a vibration amplitude of 4.34 nm has been achieved for 350nm-thick membranes under actuation voltages of 1 V of V-ac and 8 V of V-dc. (c) 2017 Author(s).