Nanofiber-based electronic devices have attracted considerable interest owing to their conformal integration on complicated surfaces, flexibility, and sweat permeability. However, building complicated electronics on nanomesh structure has not been successful because of their inferior mechanical properties and processability. This limits their practical application. To achieve systemlevel device applications, organic field-effect transistors are one of the key components to be integrated with various sensors. Herein, a successful method for fabricating a biocompatible, ultrathin (≈1.5 µm), lightweight (1.85 g m -2 ), and mechanically durable all-nanofiber-based organic transistor is reported that can be in conformal contact with curved skin. Furthermore, it is the first development with a substrate-less nanomesh organic field effect transistor. The devices exhibit satisfactory electrical performance, including an on/off value of 3.02 × 10 4 ± 0.9 × 10 4 , saturation mobility of 0.05 ± 0.02 cm 2 V − 1 s − 1 , subthreshold slope of 1.7 ± 0.2 V dec -1 , and threshold voltage of −6 ± 0.5 V. The mechanism of crack initiation is analyzed, via simulation, to understand the deformation of the nanomesh transistors. Furthermore, active matrix integrated tactile sensors entirely on the nanomeshes is successfully demonstrated, indicating their potential applicability in the field of biomedical electronics.

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Polymer nanofiber-based porous structures ("breathable devices") have been developed for breathable epidermal electrodes, piezoelectric nanogenerators, temperature sensors, and strain sensors, but their applications are limited because increasing the porosity reduces device robustness. Herein, we report an approach to produce ultradurable, cost-effective breathable electronics using a hierarchical metal nanowire network and an optimized photonic sintering process. Photonic sintering significantly reduces the sheet resistance (16.25 to 6.32 Ω sq −1 ) and is 40% more effective than conventional thermal annealing (sheet resistance: 12.99 Ω sq −1 ). The mechanical durability of the sintered (648.9 Ω sq −1 ) sample is notably improved compared to that of the untreated (disconnected) and annealed (19.1 kΩ sq −1 ) samples after 10,000 deformation cycles at 40% tensile strain. The sintered sample exhibits ∼29 times less change in electrical performance compared to the thermally annealed sample. This approach will lead to the development of affordable and ultradurable commercial breathable electronics.

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Carbon nanowalls (CNWs), which are used as electrodes for secondary batteries in energy storage systems (ESSs), have the widest reaction surface area among the carbon-based nanomaterials, but their application is rare due to their low adhesion with substrates. Indium tin oxide (ITO), a representative transparent conducting oxide (TCO) material, is widely used as the electrode for displays, solar cells, etc. Titanium nitride (TiN) is a well-used material as an interlayer for improving the adhesion between two materials. In this study, ITO or TiN thin films were used as an interlayer to improve the adhesion between a CNW and a substrate. The interlayer was deposited on the substrate using a radio frequency (RF) magnetron sputtering system with a four-inch TiN or ITO target. CNWs were grown on the interlayer-coated substrate using a microwave-plasma-enhanced chemical vapor deposition (MPECVD) system with a mixture of methane (CH 4 ) and hydrogen (H 2 ) gases. The adhesion of the CNW/interlayer/substrate structure was observed through ultrasonic cleaning.

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We conducted experiments to improve the electrical properties of the CNW (carbon nanowall), which has lower electrical properties than other carbon allotropes such as graphene and CNT (carbon nanotube), and report the results through this article. The carbon nanowall has an amorphous buffer layer, leading to low electrical properties, and MWCNT (multi-walled carbon nanotube) was used as a buffer layer to improve this issue, and then a CNW was grown on it by CVD (chemical vapor deposition). Then, the content of MWCNT was adjusted to 30 µL, 50 µL, and 70 µL to analyze the electrical properties accordingly. Alteration in carrier concentration, carrier mobility and resistivity were observed as electrical properties. Dramatic changes in electrical properties with MWCNT content were identified. The ohmic contact state between the MWCNT-based buffer layer and the CNW was investigated by analysis of the I-V and I-R characteristics and the electrical stability according to the linearity of the curve.

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