Interfacing Perforated Eardrums with Graphene-Based Membranes for Broadband Hearing Recovery.

Eardrum perforation and associated hearing loss is a global health problem. Grafting perforated eardrum with autologous tissues in clinic can restore low-frequency hearing but often leaves poor recovery of high-frequency hearing. In this study, the potential of incorporating a thin multilayered graphene membrane (MGM) into the eardrum for broadband hearing recovery in rats is examined. The MGM shows good biocompatibility and biostability to promote the growth of eardrum cells in a regulated manner with little sign of tissue rejection and inflammatory response. After three weeks of implantation, the MGM is found to be encapsulated by a thin layer of newly grown tissue on both sides without a significant folded overgrowth that is often seen in natural healing. The perforation is well sealed, and broadband hearing recovery (1-32 kHz) is enabled and maintained for at least 2 months. Mechanical simulations show that the high elastic modulus of MGM and thin thickness of the reconstructed eardrum play a critical role in the recovery of high-frequency hearing. This work demonstrates the promise of the use of MGM as a functional graft for perforated eardrum to recover hearing in the broadband frequency region and suggests a new acoustics-related medical application for graphene-related 2D materials.

Ultra-Broadband Strong Electromagnetic Interference Shielding with Ferromagnetic Graphene Quartz Fabric.

Flexible electromagnetic interference (EMI) shielding materials with ultrahigh shielding effectiveness (SE) are highly desirable for high-speed electronic devices to attenuate radiated emissions. For hindering interference of their internal or external EMI fields, however, a metallic enclosure suffers from relatively low SE, band-limited anti-EMI responses, poor corrosion resistance, and non-adaptability to the complex geometry of a given circuit. Here, a broadband, strong EMI shielding response fabric is demonstrated based on a highly structured ferromagnetic graphene quartz fiber (FGQF) via a modulation-doped chemical vapor deposition (CVD) growth process. The precise control of the graphitic N-doping configuration endows graphene coatings on specifically designable quartz fabric weave with both high conductivity (3906 S cm-1 ) and high magnetic responsiveness (a saturation magnetization of ≈0.14 emu g-1 under 300 K), thus attaining synergistic effect of EMI shielding and electromagnetic wave (EMW) absorption for broadband anti-EMI technology. The large-scale durable FGQF exhibits extraordinary EMI SE of ≈107 dB over a broadband frequency (1-18 GHz), by configuring ≈20 nm-thick graphene coatings on a millimeter-thick quartz fabric. This work enables the potential for development of an industrial-scale, flexible, lightweight, durable, and ultra-broadband strong shielding material in advanced applications of flexible anti-electronic reconnaissance, antiradiation, and stealthy technologies.

Multi-Frequency Resonance Behaviour of a Si FractalNEMS Resonator.

Novel Si-based nanosize mechanical resonator has been top-down fabricated. The shapeof the resonating body has been numerically derived and consists of seven star-polygons that forma fractal structure. The actual resonator is defined by focused ion-beam implantation on a SOIwafer where its 18 vertices are clamped to nanopillars. The structure is suspended over a 10 mtrench and has width of 12 m. Its thickness of 0.040 m is defined by the fabrication process andprescribes Young's modulus of 76 GPa which is significantly lower than the value of the bulk material.The resonator is excited by the bottom Si-layer and the interferometric characterisation confirmsbroadband frequency response with quality factors of over 800 for several peaks between 2 MHzand 16 MHz. COMSOL FEM software has been used to vary material properties and residual stressin order to fit the eigenfrequencies of the model with the resonance peaks detected experimentally.Further use of the model shows how the symmetry of the device affects the frequency spectrum.Also, by using the FEM model, the possibility for an electrical read out of the device was tested. Theexperimental measurements and simulations proved that the device can resonate at many differentexcitation frequencies allowing multiple operational bands. The size, and the power needed foractuation are comparable with the ones of single beam resonator while the fractal structure allowsmuch larger area for functionalisation.