This study reports on the fabrication of pressure/temperature/strain sensors and all‐solid‐state flexible supercapacitors using only polydimethylsiloxane coated microporous polypyrrole/graphene foam ...composite (PDMS/PPy/GF) as a common material. A dual‐mode sensor is designed with PDMS/PPy/GF, which measures pressure and temperature with the changes of current and voltage, respectively, without interference to each other. The fabricated dual‐mode sensor shows high sensitivity, fast response/recovery, and high durability during 10 000 cycles of pressure loading. The pressure is estimated using the thermoelectric voltage induced by simultaneous increase in temperature caused by a finger touch on the sensor. Additionally, a resistor‐type strain sensor fabricated using the same PDMS/PPy/GF could detect the strain up to 50%. Flexible, high performance supercapacitor used as a power supply is fabricated with electrodes of PPy/GF for its high surface area and pseudocapacitance. Furthermore, an integrated system of such fabricated multifunctional sensors and a supercapacitor on a skin‐attachable flexible substrate using liquid–metal interconnections operates well, whereas sensors are driven by the power of the supercapacitor. This study clearly demonstrates that the appropriate choice of a single functional material enables fabrication of active multifunctional sensors for pressure, temperature, and strain, as well as the supercapacitor, that could be used in wirelessly powered wearable devices.
High‐performance solid‐state supercapacitors and multifunctional sensors sensitive to pressure, temperature, and strain are fabricated using a single common active material of microporous polydimethylsiloxane coated microporous polypyrrole/graphene foam composite. Furthermore, these sensors could be wirelessly driven with the integrated supercapacitors on a single flexible and skin‐attachable substrate.
Abstract
Microplastics (MPs) are present not only in the environment but also in drinking water, food, and consumer products. These MPs being toxic, carcinogenic, endocrine disrupting, and genetic ...risk creators cause several diseases. Despite various approaches, the development of onsite applicable, facile, and quick MP detection methods is still challenging. Here, 3D‐plasmonic gold nanopocket (3D‐PGNP) nanoarchitecture is formed on a paper substrate for simultaneous MP filtration and detection. The paper‐based 3D‐PGNP is integrated with a syringe filter device, and then, MP‐containing solutions are injected through the syringe. Subsequent detection of the MPs using the surface‐enhanced Raman scattering (SERS) successfully identifies the MPs without pretreatment. The interface and volumetric hotspot generation of 3D‐PGNP around the captured MPs significantly improves the sensitivity, which is confirmed by finite‐difference time‐domain simulation. Then, the SERS mapping images obtained from a portable Raman spectrometer are transformed into digital signals via machine learning (ML) technique to identify and quantify the MP distribution. The developed SERS‐ML‐based MP detection method is applied for mixture MPs and for real matrix samples, demonstrating that the method provides improved accuracy. This system is expected to be used for various MPs detection and for environmentally hazardous substances, such as bacteria, viruses, and fungi.
Recently, many companies have introduced automated defect detection methods for defect-free PCB manufacturing. In particular, deep learning-based image understanding methods are very widely used. In ...this study, we present an analysis of training deep learning models to perform PCB defect detection stably. To this end, we first summarize the characteristics of industrial images, such as PCB images. Then, the factors that can cause changes (contamination and quality degradation) to the image data in the industrial field are analyzed. Subsequently, we organize defect detection methods that can be applied according to the situation and purpose of PCB defect detection. In addition, we review the characteristics of each method in detail. Our experimental results demonstrated the impact of various degradation factors, such as defect detection methods, data quality, and image contamination. Based on our overview of PCB defect detection and experiment results, we present knowledge and guidelines for correct PCB defect detection.
The intestinal microbiota affect various physiological traits of host animals such as brain development, obesity, age, and the immune system. In the swine industry, understanding the relationship ...between intestinal microbiota and growth stage is essential because growth stage is directly related to the feeding system of pigs, thus we studied the intestinal microbiota of 32 healthy pigs across five sows at 10, 21, 63, 93, and 147 d of ages. The intestinal microbiota were altered with growth of pigs and were separated into three distinct clusters. The relative abundance of several phyla and genera were significantly different between growth stages. We observed co-occurrence pattern of the intestinal microbiota at each growth stage. In addition, we predicted the functions of the intestinal microbiota and confirmed that several KEGG pathways were significantly different between growth stages. We also explored the relationship between the intestinal microbiota and innate factors such as the maternal effect and gender. When pigs were young, innate factors affected on construction of intestinal microbiota, however this tendency was disappeared with growth. Our findings broaden the understanding of microbial ecology, and the results will be used as a reference for investigating host-microbe interactions in the swine industry.
Elemental phosphorus exhibits fascinating structural varieties and versatile properties. The unique nature of phosphorus bonds can lead to the formation of extremely complex structures, and detailed ...structural information on some phosphorus polymorphs is yet to be investigated. In this study, we investigated an unidentified crystalline phase of phosphorus, type‐II red phosphorus (RP), by combining state‐of‐the‐art structural characterization techniques. Electron diffraction tomography, atomic‐resolution scanning transmission electron microscopy (STEM), powder X‐ray diffraction, and Raman spectroscopy were concurrently used to elucidate the hidden structural motifs and their packing in type‐II RP. Electron diffraction tomography, performed using individual crystalline nanowires, was used to identify a triclinic unit cell with volume of 5330 Å3, which is the largest unit cell for elemental phosphorus crystals up to now and contains approximately 250 phosphorus atoms. Atomic‐resolution STEM imaging, which was performed along different crystal‐zone axes, confirmed that the twisted wavy tubular motif is the basic building block of type‐II RP. Our study discovered and presented a new variation of building blocks in phosphorus, and it provides insights to clarify the complexities observed in phosphorus as well as other relevant systems.
The crystal structure of type‐II red phosphorus is investigated by various structural characterizations, including 3D electron diffraction, atomic‐resolution STEM imaging, and powder X‐ray diffraction. A triclinic unit cell with a large volume containing around 250 phosphorus atoms is identified via 3D electron diffraction. The twisted wavy tubular motif, a new variation of building blocks in phosphorus, is also revealed via STEM.
Surface‐enhanced Raman spectroscopy (SERS) based on nanostructured metals has promise as a nondestructive tool for sensitive molecular detection. However, metal surfaces are prone to fouling by the ...nonspecific adsorption of macromolecules, which limits the selective detection of small molecules in complex fluids. Therefore, samples must be purified and enriched before Raman analysis, which makes on‐site detection difficult. In the present work, Au nanopillar arrays are encapsulated with ultra‐thin hydrogel skins to protect the metal surfaces against macromolecular interferents while selectively allowing the infusion of small target molecules. In addition, densely packed Au nanostructures are produced in situ in the 3D mesh of the hydrogel skin via electrodeposition, which effectively captures targets into dense plasmonic nanogaps, providing rapid and ultrasensitive molecular detection. The synergistic influence of the size‐selective permeability of the hydrogel skin and the in situ formation of hotspots enables the direct, highly sensitive detection of pyocyanin dissolved in an aqueous solution of bovine serum albumin and human serum. It is believed that the new nanocomposite materials and techniques will enable rapid and affordable SERS‐based on‐site analysis and point‐of‐care testing.
Densely packed interconnected Au nanostructures are produced in a 3D ultra‐thin hydrogel skin via in situ electrodeposition. The in situ formation of abundant nanogaps among the Au nanostructures enables the effective capture of target molecules on SERS hotspots, and the hydrogel skin provides selective exclusion of adhesive macromolecules.
Non-small cell lung cancer (NSCLC) is one of the leading causes of death from cancer worldwide. The delivery and controlled regulation of miRNAs via exosomes is known as a potential therapeutic ...approach in the treatment of cancer. In this study, human cell-derived exosomes were used as delivery vehicles for miRNAs, and we investigated their anti-tumor and anti-angiogenic effects on NSCLCs that were cultured in 2D and 3D microfluidic devices. We demonstrated that exosomes that contained miRNA-497 (miR-497) effectively suppressed tumor growth and the expression of their associated genes, i.e., yes-associated protein 1 (YAP1), hepatoma-derived growth factor (HDGF), cyclin E1 (CCNE1), and vascular endothelial growth factor-A (VEGF-A), in A549 cells. Also, the level of VEGF-A-mediated angiogenic sprouting was decreased drastically in human umbilical vein endothelial cells (HUVECs) cultured in a microfluidic device. To mimic the in vivo-like tumor microenvironment of NSCLC, A549 cells were co-cultured with HUVECs in a single device, and miR-497-loaded exosomes were delivered to both types of cells. As a result, both the tube formation of endothelial cells and the migration of tumor decreased dramatically compared to the control. This indicated that miR-497 has synergistic inhibitory effects that target tumor growth and angiogenesis, so exosome-mediated miRNA therapeutics combined with the microfluidic technology could be a predictive, cost-efficient translational tool for the development of targeted cancer therapy.
As transparent, flexible, and wearable organic electronics degrade under normal outdoor environmental conditions (e.g., water vapor, oxygen, and UV light) and extreme environments, including washing ...or rain, a customized encapsulation technology is required to improve device reliability. Herein, a simple process is presented for fabricating multifunctional hazy substrates (MFHSs) with excellent gas diffusion barrier (GDB), flexibility, UV reflectance, light scattering, and waterproof properties. First, a spiky polyethylene terephthalate (PET) surface is produced with 76.0% optical haze through ion‐beam treatment followed by the formation of a hydrophobic layer to achieve a waterproof effect (contact angle: 153.3°). Then, a multifunctional multibarrier film is fabricated based on a nano‐laminated distributed Bragg reflector and functional polymer on the functional PET substrate to serve as a GDB and UV filter. This multibarrier film has excellent mechanical and chemical stabilities, in addition to having a water vapor transmission rate of 10−6 g m−2 day−1 and UV transmittance of <3%. The so‐fabricated MFHS not only increases the device efficiency by 73% but also enables a highly flexible and environmentally stable organic light–emitting diode. The surface treatment and encapsulation technologies developed in this study are expected to increase the lifetime of organic devices and facilitate high outdoor usability.
The ion‐beam‐treated functional polymersubstrate has an optical haze of >70% and is also superhydrophobic. Furthermore, a multifunctional multibarrier that canovercome the disadvantages of polymer substrate is developed. The encapsulation, based on an atomic‐layer‐deposited nanolaminateand functional polymer, achieves a water vapor transmission rate of 10–6 g m–2 day–1 and UV transmittance of 3%, providing a mechanically andenvironmentally robust multibarrier.
Effective hotspot engineering with facile and cost-effective fabrication procedures is critical for the practical application of surface-enhanced Raman spectroscopy (SERS). We propose a SERS ...substrate composed of a metal film over polyimide nanopillars (MFPNs) with three-dimensional (3D) volumetric hotspots for this purpose. The 3D MFPNs were fabricated through a two-step process of maskless plasma etching and hydrogel encapsulation. The probe molecules dispersed in solution were highly concentrated in the 3D hydrogel networks, which provided a further enhancement of the SERS signals. SERS performance parameters such as the SERS enhancement factor, limit-of-detection, and signal reproducibility were investigated with Cyanine5 (Cy5) acid Raman dye solutions and were compared with those of hydrogel-free MFPNs with two-dimensional hotspots. The hydrogel-coated MFPNs enabled the reliable detection of Cy5 acid, even when the Cy5 concentration was as low as 100 pM. We believe that the 3D volumetric hotspots created by introducing a hydrogel layer onto plasmonic nanostructures demonstrate excellent potential for the sensitive and reproducible detection of toxic and hazardous molecules.
The concept of an intelligent reflecting surface (IRS) has recently emerged as a promising solution for improving the coverage and energy/spectral efficiency of future wireless communication systems. ...However, as the number of reflecting elements in an IRS increase, the beam training protocol in IRS-assisted millimeter-wave (mmWave) cellular systems requires a large beam training time because it needs to find the best beam pairs for the link between the base station (BS) and the IRS, as well as the link between the IRS and the mobile station (MS). In this paper, a fast beam training technique for IRS-assisted mmWave cellular systems with a uniform rectangular array is proposed for detecting the best beam pairs of BS-IRS and IRS-MS links simultaneously. Two different types of beam training signals (BTSs) are proposed to distinguish simultaneously transmitted beams from the BSs in multi-cell multi-beam environments: the Zadoff-Chu sequence based BTS (ZC-BTS) and m-sequence based BTS (m-BTS). The correlation properties of ZC-BTSs and m-BTSs are analyzed in multi-cell multi-beam environments. In addition, the effect of symbol time offset on the ZC-BTS and m-BTS is analyzed. Finally, simulation results reveal that the proposed technique can significantly reduce the beam training time for IRS-assisted mmWave cellular systems.
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