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A laser-induced-graphene (LIG) pattern fabricated using a 355 nm pulsed laser was applied to a strain sensor. Structural analysis and functional evaluation of the LIG strain sensor were performed by Raman spectroscopy, scanning electron microscopy (SEM) imaging, and electrical–mechanical coupled testing. The electrical characteristics of the sensor with respect to laser fluence and focal length were evaluated. The sensor responded sensitively to small deformations, had a high gauge factor of ~160, and underwent mechanical fracture at 30% tensile strain. In addition, we have applied the LIG sensor, which has high sensitivity, a simple manufacturing process, and good durability, to human finger motion monitoring.

Many studies have been conducted to fabricate unique structures on flexible substrates and to apply such structures to a variety of fields. However, it is difficult to produce unique structures such as multilayer, nanospheres and porous patterns on a flexible substrate. We present a facile method of nanospheres based on laser-induced porous graphene (LIPG), by using laser-induced plasma (LIP). We fabricated these patterns from commercial polyimide (PI) film, with a 355 nm pulsed laser. For a simple one-step process, we used laser direct writing (LDW), under ambient conditions. We irradiated the PI film at a defocused plane −4 mm away from the focal plane, for high pulse overlap rate. The effect of the laser scanning speed was investigated by FE-SEM, to observe morphological characterization. Moreover, we confirmed the pattern characteristics by optical microscope, Raman spectroscopy and electrical experiments. The results suggested that we could modulate the conductivity and structural color by controlling the laser scanning speed. In this work, when the speed of the laser is 20 mm/s and the fluence is 5.28 mJ/cm2, the structural color is most outstanding. Furthermore, we applied these unique characteristics to various colorful patterns by controlling focal plane.

Three-dimensional (3-D) porous graphitic structures have great potential for sensing applications due to their conductive carbon networks and large surface area. In this work, we present a method for facile fabrication of hair-like laser induced graphene (LIG) patterns using a laser scribing system equipped with a 355 nm pulsed laser. The polyimide (PI) film was positioned on a defocused plane and irradiated at a slow scanning speed using a misaligned laser beam. These patterns have the advantages of a large surface area and abundant oxidation groups. We have applied the hair-like LIG patterns to a humidity sensor. The humidity sensor showed good sensitivity characteristics and a large amount of electronic carriers can be stored.

The increasing demand for versatile graphene-based materials, incorporating semimetal nanoparticles (NPs), is driving contemporary societies towards platforms that harness solar radiation for biocidal activity, de-icing, and photodegradation. This study investigates the photoinduced antibacterial activity, de-icing, and photocatalytic properties of Cu-doped TiO 2 /Ultraviolet (UV)-Laser-Induced Graphene (LIG). Cu-doped TiO 2 /UV-LIG exhibits considerable promise when subjected to solar radiation, particularly in applications such as de-icing, photodegradation and antibacterial efficacy. Characterized by nanopores and a surface area of 396 m 2 /g, Cu-doped TiO 2 /UV-LIG achieved a noteworthy temperature of 91.7°C under 1 SUN irradiance, thus establishing a significant milestone in the field of LIG. Initially, it demonstrated exceptional phenol degradation efficiency at 86%, and this efficiency remained noteworthy at 83% even after undergoing five cycles of use, thus emphasizing its enduring degradation capacity. Moreover, at 0.5 SUN intensity, it demonstrated remarkable efficacy in eradicating over 99.999% of foodborne pathogens.

Homogenously dispersed Cu oxide nanoparticles on laser-induced graphene (LIG) were fabricated using a simple two-step laser irradiation. This work emphasized the synergetic photo-electrothermal effect in Cu oxide particles embedded in LIG. Our flexible hybrid composites exhibited high mechanical durability and excellent thermal properties. Moreover, the Cu oxide nanoparticles in the carbon matrix of LIG enhanced the light trapping and multiple electron internal scattering for the electrothermal effect. The best conditions for deicing devices were also studied by controlling the amount of Cu solution. The deicing performance of the sample was demonstrated, and the results indicate that the developed method could be a promising strategy for maintaining lightness, efficiency, excellent thermal performance, and eco-friendly 3D processing capabilities.

Due to the limited availability of agricultural land, pH sensing is becoming more and more important these days to produce efficient agricultural products. Therefore, to fabricate eco-friendly and disposable sensors, the black carbon, which is called biochar, is formed by irradiation of a UV pulsed laser having a wavelength of 355 nm onto wood and applying the resulting material as a pH sensor. The surfaces of three types of wood (beech, cork oak, and ash) were converted to the graphitic structure after UV laser irradiation; their morphologies were investigated. In addition, since the content of lignin, an organic polymer, is different for each wood, optimal laser irradiation conditions (laser fluence) needed to form these woods into pH sensors were considered. Depending on the degree of oil-like material generated after laser irradiation, a disposable pH sensor that can be used from one to three times is fabricated; due to the environmental characteristics of wood and biochar, the sensor shows high availability in that it can be easily discarded after use on agricultural land. After that, it can be used as filter in soil. Our wood-based pH sensor sensitively measures sequential changes from pH 4 to pH 10 and shows a very linear change of △R/R, indicating its potential for use in agriculture.

In this study, we developed an effective and rapid process for nanoscale ink printing, direct laser interference ink printing (DLIIP), which involves the photothermal reaction of a copper-based metal–organic decomposition ink. A periodically lined copper pattern with a width of 500 nm was printed on a 240 μm-wide line at a fabrication speed of 17 mm/s under an ambient environment and without any pre- or post-processing steps. This pattern had a resistivity of 3.5 μΩ∙cm, and it was found to exhibit a low oxidation state that was twice as high as that of bulk copper. These results demonstrate the feasibility of DLIIP for nanoscale copper printing with fine electrical characteristics.

This paper demonstrates a simple fabrication method of porous metal structures using liquid phase solution (copper formate solution) based on UV pulse laser deposition. This process can produce arbitrary metal 3D structures at room temperature and atmosphere. Primary reactions are redox processes by photothermal effect. Local temperature elevation induced by laser exposure activates selective copper formation effects. It can be a method of 3D additive manufacturing processes, which has some advantages that no supporter and no shielding environment preventing the oxidation are required. Also, the density of porous copper structure could be predicted by concentration of solution. These experimental results showed that it was feasible to produce the metal foam-typed structures, and thus it would provide the potential possibilities of additive manufacturing by layering various metal structures. In the future, this process will be applicable to catalyst exchangers, electrodes, filters, and heat exchangers.

The incidence of tuberculosis remains high in South Korea; the management of latent tuberculosis infection (LTBI) has become the prime target for reducing the infection rate. The management of pediatric LTBI is especially crucial because children can serve as a long-term source of infection upon developing active tuberculosis. Therefore, it is important to assess pediatric LTBI using contact investigation and follow-up. We conducted a retrospective study on children aged between 0 and 18 years who visited our hospital for tuberculosis contact screening from February 2012 to February 2021. Tuberculosis index cases and their clinical characteristics were also reviewed retrospectively. A total of 350 children were investigated, and 68 of 247 (27.5%) were diagnosed with LTBI. The rate of LTBI (r = 7.98, p < 0.001) and the risk of loss to follow-up (r = 27.038, p < 0.001) were higher in cases with close household contact. Sputum (r = 10.992, p < 0.001) and positive acid-fast bacillus (AFB) stain (r = 4.458, p = 0.001) in tuberculosis index cases were related to the diagnosis of LTBI in pediatric contacts. Active management is needed for tuberculosis screening in pediatric contacts, especially when the contacts are older and the index case is within the family, and when the index case has sputum and has tested positive for AFB smear.

With the advancement in the field of nanotechnology, nanopatterning finds extensive application not only in high value-added products but also in inexpensive products. In addition, the technology required for the mass production of inexpensive products, such as the continuous roll-to-roll (R2R) process, is rapidly emerging. Extensive research has been conducted on the manufacture of submicron- and nano- molds. In this study, we have proposed a laser interference exposure for fabricating nanopatterned cylindrical molds that can be used in continuous roll-to-roll patterning. Additionally, we have demonstrated spiral exposure process to fabricate a seamless patterning on a cylinder (length of 300 mm and diameter of 100 mm) using a prism. The pattern was transferred to the flat mold using UV resin and measured using a field emission scanning electron microscope; the pattern was measured to have a uniform with nano pattern line width (75 nm) and a sub-micron period (286 nm). It was observed that the proposed method for fabrication of the roll mold using laser interference lithography is a fast and reliable seamless patterning.