Neural interfaces that unify diagnostic and therapeutic functionalities hold particular promise for advancing both fundamental neuroscience and clinical neurotechnology. Functional ultrasound imaging (fUSI) has recently emerged as a powerful modality for high-resolution, non-invasive monitoring of brain function and structure. However, conventional metal-based microelectrodes typically impede ultrasound propagation, limiting compatibility with fUSI. Here, we present flexible, ultrasound-transparent neural interfaces that retain practical metal thicknesses while achieving high acoustic transparency. We introduce a theoretical and simulation-based framework to investigate the conditions under which commonly used polymers and metals in neural interfaces can become acoustically transparent. Based on these insights, we propose design guidelines that maximise ultrasound transmission through soft neural interfaces. We experimentally validate our approach through immersion experiments and by demonstrating the acoustic transparency of a suitably engineered interface using fUSI in phantom and in vivo experiments. Finally, we discuss the potential extension of this approach to therapeutic focused ultrasound (FUS). This work establishes a foundation for the development of multimodal neural interfaces with enhanced diagnostic and therapeutic capabilities, enabling both scientific discovery and translational impact.

Due to their outstanding electrical and thermal properties, graphene and related materials have been proposed as ideal candidates for the development of lightweight systems for thermoelectric applications. Recently, the nanolaminate architecture that entails alternation of continuous graphene monolayers and ultrathin polymer films has been proposed as an efficient route for the development of composites with impressive physicochemical properties. In this work, we present a novel layer-by-layer approach for the fabrication of highly ordered, flexible, heat-resistant, and electrically conductive freestanding graphene/polymer nanolaminates through alternating Marangoni-driven self-assembly of reduced graphene oxide (rGO) and poly(ether imide) (PEI) films. The microstructure, the mechanical behavior, and the electrical conductivity of the produced Marangoni rGO/PEI nanolaminates are studied as a function of rGO content (up to 5.2 vol %). These nanolaminate thin films show excellent heating properties, with fast heating responses at high temperatures to maximum temperatures at ca. 325 °C due to the Joule heating effect, at maximum rates of 444 °C/s, thus bringing forward an impressive potential of these materials for electrothermal applications. The areal power density was found to be 30 kW/m² for the 5.20% volume fraction of rGO and 325 °C temperature. The robust highly flexible heaters developed in this research hold great promise for a whole range of applications.

As an emerging class of materials, nanocarbons have attracted significant interest for practical applications due to their remarkable mechanical, electrical and thermal properties coupled with high surface areas and tunable surface chemistry. However, challenges like high aspect ratios and poor dispersibility in polymer matrices hinder their widespread use in technological applications. The problems are most prominently resolved with the use of free-standing nanocarbon sheets. The present paper reviews recent advancements in fabricating and utilizing free-standing sheets consisting of various nanocarbons: carbon nanotubes and 2D materials like graphene, graphene oxide, and reduced graphene oxide. It initially delves into the nanomechanics of these sheets, focusing on inter-particle cross-linking and nacre-like microstructures. Energy storage applications are also examined, with emphasis on the role of nanocarbon-based sheets in the enhancement of specific energy capacity and performance retention of batteries, electric double layer supercapacitors, and pseudocapacitors. In the field of electromagnetic interference shielding, the sheets' superior electrical conductivity and microstructures, which amplify internal reflections in the GHz and THz regions, are showcased. Their potential in heat dissipation, owing to their high thermal conductivity and large surface area, is also explored. Additionally, they are reviewed for membrane-based separation processes, specifically gas separation, reverse osmosis, forward osmosis, and pervaporation, highlighting properties like ion selectivity and chlorine resistance. The last discussion concerns the role of nanocarbon-based sheets in catalysis where they can enhance reaction efficiencies and promote sustainable solutions. Either as catalysts and/or supports, with key features such as high surface area, electrical conductivity, and adaptable functionalities, they showcase significant potential in various catalytic processes like electrocatalysis and environmental remediation.