Mutually Reinforced Polymer–Graphene Bilayer Membranes for Energy‐Efficient Acoustic Transduction

Abstract

Graphene holds promise for thin, ultralightweight, and high‐performance nanoelectromechanical transducers. However, graphene‐only devices are limited in size due to fatigue and fracture of suspended graphene membranes. Here, a lightweight, flexible, transparent, and conductive bilayer composite of polyetherimide and single‐layer graphene is prepared and suspended on the centimeter scale with an unprecedentedly high aspect ratio of 105. The coupling of the two components leads to mutual reinforcement and creates an ultrastrong membrane that supports 30 000 times its own weight. Upon electromechanical actuation, the membrane pushes a massive amount of air and generates high‐quality acoustic sound. The energy efficiency is ≈10–100 times better than state‐of‐the‐art electrodynamic speakers. The bilayer membrane's combined properties of electrical conductivity, mechanical strength, optical transparency, thermal stability, and chemical resistance will promote applications in electronics, mechanics, and optics.

Array of Graphene Variable Capacitors on 100 mm Silicon Wafers for Vibration-Based Applications

“…For example, single-layer graphene was suspended over a lightweight, flexible, transparent, and conductive bilayer composite of polyetherimide to create an energy-efficient, high-performance nanoelectromechanical transducer [ 27 ]. Graphene membranes have also been used to make a graphene varactor, allowing its capacitance to be finely tuned using voltage-induced deflection [ 28 , 29 ].…”

Viscoelastic Response of Graphene Oxide‐Based Membranes and Efficient Broadband Sound Transduction

“…The low mass, good mechanical properties, high electrical and thermal conductivity have made graphene‐based materials such as CVD graphene and reduced graphene oxide interesting materials for different types of acoustic transducers including electrostatic (ESL) [ 5,6 ] and thermoacoustic loudspeakers. [ 7 ] Zhou et al.…”

“…The fragility of multilayer graphene is a concern for long‐term durability. More recently, Khan et al [ 6 ] reported a mechanically robust ESL with a diaphragm comprising a single layer graphene atop a polyetherimide membrane. The diaphragm has shown promise for low power consumption and SPL in the mid‐ to high‐ frequency range (>500 Hz) comparable to commercial microspeakers.…”

Polarization-Driven Asymmetric Electronic Response of Monolayer Graphene to Polymer Zwitterions Probed from Both Sides

“…Screening is also tied to a material’s conductivity, which, together with polarizability, is a key performance element for graphene-based bio- and chemical sensors . Recent progress in the preparation of polymer-containing graphene devices includes doping by ultrathin polymer layers , and fabrication of free-standing polymer-supported graphene membranes . A combination of such strategies, as described here, allowed for more direct probing of the graphene–polymer interface for the first time without perturbation associated with the thickness of the organic layer.…”

“…43 Recent progress in the preparation of polymercontaining graphene devices includes doping by ultrathin polymer layers 24,26 and fabrication of free-standing polymersupported graphene membranes. 44 A combination of such strategies, as described here, allowed for more direct probing of the graphene−polymer interface for the first time without perturbation associated with the thickness of the organic layer. Previous observations have shown that overlayer thickness has a complex impact on surface electronic measurements, 26 and thus minimizing this influence is of great interest.…”