Weavable sensing fibers with superior mechanical strength and sensing functionality are crucial for the realization of wearable textile sensors. However, in the fabrication of previously reported wearable sensing fibers, additional processes such as reduction, doping, and coating were essential to satisfy both requirements. The sensing fibers should be continuously synthesized in a scalable process for commercial applications with high reliability and productivity, which was challenging. In this study, we first synthesize mass-producible wearable sensing fibers with good mechanical properties and sensing functionality without additional processes by incorporating carbon nanotubes (CNTs) into distinct nanocellulose. Nanocellulose extracted from tunicate (TCNF) is homogeneously composited with single-walled CNTs, and composite fibers (TCNF/CNT) are continuously produced in aligned directions by wet spinning, facilitating liquid-crystal properties. The TCNF/CNT fibers exhibit a superior gas (NO 2 )-sensing performance with high selectivity and sensitivity (parts-per-billion detection). In addition, the TCNF/CNT fibers can endure complex and harsh distortions maintaining their intrinsic sensing properties and can be perfectly integrated with conventional fabrics using a direct weaving process. Our meter-scale scalable synthesis of functional composite fibers is expected to provide a mass production platform of versatile wearable sensors.

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Transition metal dichalcogenides (TMDs) have attracted significant interest as one of the key materials in future electronics such as logic devices, optoelectrical devices, and wearable electronics. However, a complicated synthesis method and multistep processes for device fabrication pose major hurdles for their practical applications. Here, we introduce a direct and rapid method for layer-selective synthesis of MoS 2 and WS 2 structures in wafer-scale using a pulsed laser annealing system (λ = 1.06 μm, pulse duration ∼100 ps) in ambient conditions. The precursor layer of each TMD, which has at least 3 orders of magnitude higher absorption coefficient than those of neighboring layers, rigorously absorbed the incoming energy of the laser pulse and rapidly pyrolyzed in a few nanoseconds, enabling the generation of a MoS 2 or WS 2 layer without damaging the adjacent layers of SiO 2 or polymer substrate. Through experimental and theoretical studies, we establish the underlying principles of selective synthesis and optimize the laser annealing conditions, such as laser wavelength, output power, and scribing speed, under ambient condition. As a result, individual homostructures of patterned MoS 2 and WS 2 layers were directly synthesized on a 4 in. wafer. Moreover, a consecutive synthesis of the second layer on top of the first synthesized layer realized a vertically stacked WS 2 /MoS 2 heterojunction structure, which can be treated as a cornerstone of electronic devices. As a proof of concept, we demonstrated the behavior of a MoS 2 -based field-effect transistor, a skin-attachable motion sensor, and a MoS 2 /WS 2 -based heterojunction diode in this study. The ultrafast and selective synthesis of the TMDs suggests an approach to the large-area/mass production of functional heterostructure-based electronics.

Here, we studied the triboelectric properties of structurally controlled laser-induced graphene (LIG) to clarify the key factors for improving the energy harvesting performance. With a facile defocusing method, the LIG...

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Transition metal dichalcogenides (TMDC) have been identified as excellent platforms for developing the next-generation commercial flexible logic devices and sensors, owing to their outstanding mechanical, optical, and electrical properties. The TMDCs can be used to produce novel form-factors for wearable electronic devices. Typically, synthesis of large-scale TMDC thin film have been achieved by complexity vacuum-based approach. Therefore, it is essential to develop a simple and effective method to boost-up mass production of TMDC thin films on a large scale upon arbitrary substrates. In this regard, the solution-based TMDC synthesis method is advantageous because it proposes a simplification of the fabrication processes and an easy scaling-up of the material with a non-vacuum system. In this review, we summarize the evolution of the solution-based thin-film preparation and synthesis of the TMDCs; subsequently, we discuss the merits and drawbacks of the recently developed methods to form TMDC thin films directly from the deposited precursor. Finally, we discuss the practical applications of the TMDC thin films, which demonstrate the feasibility of their commercialized applications in electronic devices and sensors.

Since the breakthrough in fabricating graphene by mechanical exfoliation in 2004, numerous methods have been developed to synthesize high-quality graphene materials on a large scale, including chemical exfoliation, thermolysis, and chemical vapor deposition. Recently, laser thermal treatments have emerged as facile methods for the direct synthesis of functionalized graphene materials, which show potential for use in a wide range of applications. The graphene materials produced by laser-based syntheses are classified by the fabrication method as either laserreduced graphene or laser-induced graphene (LIG). The former is obtained through the chemical reduction of graphene oxide, while the latter utilizes the carbonization of a polymer precursor. In this review, we summarize the mechanisms of laser-assisted graphene syntheses, the structural and chemical functionalization of laser-scribed graphene, and various practical demonstrations of graphene-based materials in the field of mechanical and electrochemical sensors.

Laser‐induced graphene (LIG) has drawn attention for energy storage devices owing to its fascinating material properties as well as for its use in the effective production of porous structures. However, the low packing density of LIG, which is caused by macroscopic voids owing to rapid degassing during the instantaneous photothermal process, limits the improvement of device performance. Herein, the fabrication of compacted LIG composite is introduced, wherein, the unused voids are filled with bamboo‐like carbon nanotubes (BCNTs). The BCNTs grown directly in the voids of LIG through chemical vapor deposition (CVD) method using Cu seeds as catalysts improve the electrical conductivity, chemical activity, and mechanical flexibility, while enhancing the spatial efficiency of the porous structure. Consequently, the fabricated composite film (denoted as BCNT:LIG/Cu) delivers an energy density of 1.87 μWh cm−2, which is ≈10 times higher than that of the LIG‐based supercapacitor (0.19 μWh cm−2). Moreover, the BCNT:LIG/Cu film with a shape engineering pattern is assembled into a solid‐state supercapacitor using a gel electrolyte (PVA‐KOH), showing excellent electrochemical and mechanical stabilities under complex deformations. The proposed LIG‐based densification strategy opens up opportunities for the development of energy devices for portable power supply in practical applications.