Projects per year
Suspended vibrating membranes play a vital role as structural elements in electromechanical resonators and form the foundation of modern acoustic transducers. The realization of large scale mechanical resonators based on large and thin membranes, however, still faces several challenges. In this work, a simple and reproducible process has been developed to transfer millimeter-scale circular and square membranes composed of ~2.5 nm of graphene and a thin film of ~ 370 nm of poly(methyl methacrylate) (PMMA). The uniqueness of the demonstrated fabrication technique is the ability to produce high yield and non- ruptured suspended membranes with exceptional diameter (side length) to thickness aspect ratios of ~ 10,000. One of the perceived advantages of building a mechanical resonator from a bilayer structure, in which materials have different mechanical and thermal properties, is that such a structure can enable the use of electrothermal transduction to drive the resonator into resonance and tune its resonant frequencies. Due to the large area of the fabricated membranes, resonant frequencies within the audio range have been obtained. The frequency tuning response of circular and square membranes has been found to be influenced significantly by the magnitude of the applied voltage. A downward shift of the resonant frequency and an increase of the amplitude of vibration have been observed in response to the increase of the applied DC and AC voltages. The demonstrated fabrication technique and tuning mechanism could be employed as a platform for potential acoustic and audio applications.