Deposition of high-quality dielectric on a graphene channel is an essential technology to overcome structural constraints for the development of nano-electronic devices. In this study, we investigated a method for directly depositing aluminum oxide (Al₂O₃) on a graphene channel through nitrogen plasma treatment. The deposited Al₂O₃ thin film on graphene demonstrated excellent dielectric properties with negligible charge trapping and de-trapping in the gate insulator. A top-gate-structural graphene transistor was fabricated using Al₂O₃ as the gate dielectric with nitrogen plasma treatment on graphene channel region, and exhibited p-type transistor characteristics.

Highly flexible and stretchable graphene-based fibers are one of the most synthetically challenging materials that are suitable for next-generation wearable electronics. Graphene-based fibers used in reliable wearable devices should be multifunctional and stable. Here, we report an easy-handling fabrication method for reduced graphene oxide fibers containing semiconducting CuI and metallic Cu particles (CRGO fiber). The fibers were prepared by wet spinning and hydriodic acid treatment from a CuCl₂–ethylene glycol coagulating solution without pre-synthesized CuI and Cu particles. The fabricated CRGO fibers exhibited chemical sensitive/temperature insensitive or chemical insensitive/temperature sensitive characteristics, depending on the Cu concentration in the CRGO. This is the first demonstration of a highly selective chemical and temperature sensor with sensitivity-switching properties fabricated from twisted CRGO fibers comprising two fiber bundles with low and high Cu concentrations.

Herein, we have proposed a method that uses a highly stretchable and conductive fiber-based multi-angle fiber array, which precisely measures human joint motion in various degrees of freedom (flexion and rotation) at the shoulders, knees, and wrists in real time. By embedding conductive carbon nanotubes (CNTs) within spandex fibers of high elasticity and shape recovery ratio, we monitored joint motion stably without degrading the fiber’s conductivity even during repeated stretching and contraction of different lengths. The strain occurring in a specific direction was monitored using mapping images generated due to the change in resistance that occurred when 12 CNT-embedded spandex fibers arranged in radial lines at intervals of 15° were stretched or contracted by an external force. The proposed high-precision joint-monitoring technology measures human motion accurately and is applicable for use in wearable healthcare devices that require precise measurements.

With the increasing trend of high-rise, large-scale, and functional modern architectural structures, lightweight aggregate (LWA) concrete that exhibits excellent strength and high functionality has garnered active research attention. In particular, as the properties of concrete vary considerably with the raw materials and the proportions of aggregates in the mix, in-depth research on weight reduction, strength improvement, and functional enhancements of aggregates is crucial. This study used the negative pressure coating of a mixed solution comprising epoxy (mixture of epoxy resin and crosslinker), hyper-crosslinked polymer, and titanium oxide (TiO₂) nanoparticles on the LWA, and achieved an improvement in the strength of the LWA as well as a reduction in air pollutants such as NO_x and SO_x. Compared to a normal LWA with an aggregate impact value (AIV) of 38.7%, the AIV of the proposed epoxy–TiO₂-embedded high-strength functional LWA was reduced by approximately half to 21.1%. In addition, the reduction rates of NO_x and SO_x gases resulting from the photocatalytic properties of TiO₂ nanoparticles coated with epoxy were approximately 90.9% and 92.8%, respectively. Epoxy–TiO₂, embedded in LWAs through a mixture, exhibited stability, high strength, and a reduction in air pollutant characteristics, despite repeated water washing. The LWA proposed herein offers excellent structural and functional properties and is expected to be used in functional lightweight concrete that can be practically applied in high-rise and large-scale architectural structures.