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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. [ABSTRACT FROM AUTHOR]

Porous polymer films have been investigated for various applications. The conventional method forms microporous structures throughout a film. This paper presents a new process for forming micro/nano-porous patterns on a polyimide membrane surface using a laser and a blowing agent only in selected areas. A blowing agent was mixed in a polyimide, and the mixture was then irradiated with a laser to instantaneously heat it to the decomposition temperature of the blowing agent. Subsequently, micro/nano-porous patterns were created only in regions irradiated with the laser owing to the explosion of the blowing agent. The micro/nano-porous patterns were fabricated using 355-nm ultraviolet pulse laser processing. The pores of the porous structures were closed or open, depending on the quantity of blowing agent, laser fluence, and pulse overlap ratio. The experimental results showed that the pore density, pore size, and processing time could be adjusted. In addition, porous patterning was formed selectively and locally. Recently, micro-/nano porous patterned films have been widely used as absorbents, support cells, and sensors in industrial fields and they have considerable application potential in various fields. [ABSTRACT FROM AUTHOR]

A new type of disposable flexible sensor for hydrogen peroxide (H2O2) detection was developed by in situ synthesis of copper–ruthenium bimetallic nanoparticles on a laser-induced graphene surface (Cu–Ru/LIG). The approach produced Cu–Ru/LIG via a solid phase transfer mechanism which loaded the metal precursor onto LIG, followed by laser scribing without demanding chemical vapor deposition or solution-based reactions. Cu–Ru/LIG showed a high electrocatalytic response toward H2O2 reduction at −0.4 V vs. Ag/AgCl. The sensor also showed good selectivity and reproducibility. This method provides an alternative route to easily synthesize various catalysts on conductive substrates for sensor applications. [ABSTRACT FROM AUTHOR]

We present a novel method for simultaneous measurement of the thickness and refractive index distribution of a transparent specimen by a line-field swept-source interferometer. In this study, by illuminating with the line-field beam instead of the point-focused beam, multiple interferences along the line-field distribution are measured simultaneously by using a combination of a novel swept source of 800-nm central region and a Si-based 1024-pixel charge-coupled device (CCD) detector. When the transparent specimen has an uneven thickness or nonuniform refractive index, the whole distribution of these two parameters can be also simultaneously measured over the illuminated region with a one-step comparison process. Using four types of transparent specimens, the thickness and refractive index distribution of each sample and a group sample paired with two specimens are accurately measured during the single wavelength scanning time of 27 ms by using the swept source with a 36-Hz sweeping rate and the CCD detector with a 36-kHz line rate. [ABSTRACT FROM PUBLISHER]

The airbag is an occupant protection device widely used in the automotive industry. Federal Motor Vehicle Safety Standard 208 requires the low-risk deployment airbag system to be utilized in vehicles to protect out-of-position occupants. This paper presents a design-for-six-sigma low-risk deployment passenger airbag optimized by adding a passenger protection wrap. The passenger protection wrap reduces the cushion impact force on the passenger by ensuring pressure dispersion. A series of static tests were conducted to demonstrate the proposed system using Federal Motor Vehicle Safety Standard 208 test procedures. The test results shows that the proposed passenger airbag satisfies the criteria established by Federal Motor Vehicle Safety Standard 208 and also presents a significant improvement over conventional airbag systems. [ABSTRACT FROM AUTHOR]

Purpose: To compare the clinical efficacy and safety in children with vesicoureteral reflux (VUR) of a single injection of two different bulking agents: polydimethylsiloxane (Macroplastique) or dextranomer/hyaluronic acid copolymer (Deflux). Methods: A total of 73 patients (106 renal units, 41 boys and 32 girls) aged 2-15 years (mean age, 34.5 months) were included. A single subureteral injection of either Macroplastique or Deflux was performed in 37 children (55 ureters) and 36 children (51 ureters), respectively. VUR was grade II in 34 ureterorenal units, grade III in 23, grade IV in 31, and grade V in 18 ureterorenal units. Results: Overall, the reflux was corrected in 84 of the renal units (86%) with one injection. The correction rates, according to the reflux grade, were 91, 91, 83, and 72% for grades II-V, respectively. At the 3-month follow-up visit, reflux was corrected in 48 (87%) of 55 refluxing ureters in the Macroplastique group and in 43 (84%) of 51 refluxing ureters in the Deflux group. Conclusions: A single subureteral injection of either Macroplastique or Deflux is an effective treatment modality for children with VUR. The procedure was well tolerated, safe, and associated with low morbidity. Copyright © 2011 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The replacement of electro-thermal material in heaters with lighter and easy-to-process materials has been extensively studied. In this study, we demonstrate that laser-induced graphene (LIG) patterns could be a good candidate for the electro-thermal pad. We fabricated LIG heaters with various thermal patterns on the commercial polyimide films according to laser scanning speed using an ultraviolet pulsed laser. We adopted laser direct writing (LDW) to irradiate on the substrates with computer-aided 2D CAD circuit data under ambient conditions. Our highly conductive and flexible heater was investigated by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, X-ray diffraction, and Brunauer–Emmett–Teller. The influence of laser scanning speed was evaluated for electrical properties, thermal performance, and durability. Our LIG heater showed promising characteristics such as high porosity, light weight, and small thickness. Furthermore, they demonstrated a rapid response time, reaching equilibrium in less than 3 s, and achieved temperatures up to 190 °C using relatively low DC voltages of approximately 10 V. Our LIG heater can be utilized for human wearable thermal pads and ice protection for industrial applications. [ABSTRACT FROM AUTHOR]

Bio-compatible strain sensors based on elastomeric conductive polymer composites play pivotal roles in human monitoring devices. However, fabricating highly sensitive and skin-like (flexible and stretchable) strain sensors with broad working range is still an enormous challenge. Herein, we report on a novel fabrication technology for building elastomeric conductive skin-like composite by mixing polymer solutions. Our e-skin substrates were fabricated according to the weight of polydimethylsiloxane (PDMS) and photosensitive polyimide (PSPI) solutions, which could control substrate color. An e-skin and 3-D flexible strain sensor was developed with the formation of laser induced graphene (LIG) on the skin-like substrates. For a one-step process, Laser direct writing (LDW) was employed to construct superior durable LIG/PDMS/PSPI composites with a closed-pore porous structure. Graphene sheets of LIG coated on the closed-porous structure constitute a deformable conductive path. The LIG integrated with the closed-porous structure intensifies the deformation of the conductive network when tensile strain is applied, which enhances the sensitivity. Our sensor can efficiently monitor not only energetic human motions but also subtle oscillation and physiological signals for intelligent sound sensing. The skin-like strain sensor showed a perfect combination of ultrawide sensing range (120% strain), large sensitivity (gauge factor of ~380), short response time (90 ms) and recovery time (140 ms), as well as superior stability. Our sensor has great potential for innovative applications in wearable health-monitoring devices, robot tactile systems, and human–machine interface systems. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In the study for this paper, the 355 nm UV laser was used to modify and to deposit copper patterns onto a polyimide surface. The UV laser breaks chemical bonds and causes chemical reactions to occur on the irradiated surface due to photochemical effects and to photothermal effects. More specifically, the polyimide surface is initially modified using the UV laser and the copper is then deposited directly by the UV laser from the copper formate solution. The polyimide surface was transformed into an oxygen-rich surface by modification and copper traces were deposited on the polyimide surface. The smallest pattern was obtained at a laser fluence of 600 mJ/cm2 and a scan speed of 4.3 mm/s. The maximum thickness was 8.5 µm and the width was 55 µm. While the thickness and the width of the deposited copper traces decreased in accordance with the scan speed of the laser, the surface of the deposited copper traces is extremely rough. Furthermore, the copper had C and O impurities. The resistivity of copper traces was minimum 1.07 ×10-6 Ω·m. [ABSTRACT FROM AUTHOR]

Abstract: We observed the variation in the size of microwrinkles according to the number of unit processing cycles, which consist of polydimethyl siloxane (PDMS) casting followed by the deposition of Al. As the number of processing cycles increases, the width of the microwrinkles narrows and their height increases. After five processing cycles were completed, the width of the microwrinkles stood at 1.7–3.7μm. The top surface area of the microwrinkles became smaller upon additional processing cycles, thereby reducing the contact area between the water drops and the top surface. For this reason, the contact angle increased as the number of processing cycles increased. The contact angle measured after five processing cycles was 145°, implying that the microwrinkled surface was modified such that it became superhydrophobic. [Copyright &y& Elsevier]