3D Bristle-Structured, Knitted-Fabric-Based Triboelectric Sensors for Machine Learning-Based Motion Recognition.

With the development of electronic technology, triboelectric-based sensors have been widely researched in fields such as healthcare, rehabilitation training, and sports assistance due to their manufacturing convenience and self-powering advantages. Among them, 3D fabric-based triboelectric sensors not only possess advantages such as easy mechanized production, good breathability, and ease of wearing but also their unique 3D structure enhances the specific surface area, thereby amplifying the sensitivity. This study proposes a 3D bristle-structured fabric made by a digital knitting technology that has not been studied widely for triboelectric devices. By applying the 3D bristle structure with a large specific surface area to the single jersey fabric, the effective contact area during friction can be increased, resulting in a higher surface charge density. Additionally, the microcapacitor-like effect provided by the numerous microstructures allows the device to store more surface charge, further improving the output performance. The study systematically investigates the output performance of four different structures assembled by single jersey and 3D bristle-structured fabrics. The optimal sample exhibits a 57% higher output voltage than that of the reference 2D fabric sample. The 3D bristle-structured fabric demonstrates linear high sensitivity and distinct output performance when used as a sensor. Finally, a machine learning integration is applied to judge motion to assist a baseball pitcher in a self-training system.

Innovative strategies for protein content determination in dried laver (Porphyra spp.): Evaluation of preprocessing methods and machine learning algorithms through short-wave infrared imaging.

In this study, we explored the application of Short-Wave Infrared (SWIR) hyperspectral imaging combined with Competitive Adaptive Reweighted Sampling (CARS) and advanced regression models for the non-destructive assessment of protein content in dried laver. Utilizing a spectral range of 900-1700 nm, we aimed to refine the quality control process by selecting informative wavelengths through CARS and applying various preprocessing techniques (standard normal variate [SNV], Savitzky-Golay filtering [SG], Orthogonal Signal Correction [OSC], and StandardScaler [SS]) to enhance the model's accuracy. The SNV-OSC-StandardScaler- Support vector regression (SVR) model trained on CARS-selected wavelengths significantly outperformed the other configurations, achieving a prediction determination coefficient (Rp2) of 0.9673, root mean square error of prediction of 0.4043, and residual predictive deviation of 5.533. These results highlight SWIR hyperspectral imaging's potential as a rapid and precise tool for assessing dried laver quality, aiding food industry quality control and dried laver market growth.

Enhanced Positive Charge Performance in Triboelectric Series: Molecular Engineering of Conjugated Mesoporous Fibers for Machine Learning-Based Wearable Sensors.

With the increasing focus on triboelectric-based sensors, research on synthesizing dielectric layers from specific substances is gradually emerging. Despite numerous negatively-charged triboelectric materials, there is a scarcity of synthesizable positively-charged materials, creating a research gap. This study demonstrates the molecular design of a conjugated, mesoporous, self-assembled sheet via bottom-up synthesis. The synthesized sheet is functionalized to create a triboelectric nanogenerator. Its large specific surface area, softness, and internal space increase the actual contact area and provide adsorption sites for polypyrrole nanoparticles. The incorporation of -COO functional group enhances positive triboelectric performance, forming a dielectric layer with charge-trapping capabilities. When contact with polytetrafluoroethylene (PTFE), this structure boosts the output voltage, showing significant amplification after charge injection with minimal decay. As a demonstration, the bilayer structure is applied as a touchpad on the experimenter's arm to write symbols. The signals are input into an innovative machine-learning model to interpret the writer's intent. Additionally, the device connects to a terminal for real-time medical services, suggesting practical applications for wearable triboelectric sensors with artificial intelligence.

Enhanced N-type Semiconducting Performance of Asymmetric Monochlorinated Isoindigo-based Semiregioregular Polymers under Dynamic Forces.

The asymmetric monochlorination strategy not only effectively addresses the steric issues in conventional dichlorination but also enables the development of promising acceptor units and semiregioregular polymers. Herein, monochlorinated isoindigo (1CIID) is successfully designed and synthesized by selectively introducing single chlorine (Cl) atoms. Furthermore, the 1CIID copolymerizes with two donor counterparts, centrosymmetric 2,2'-bithiophene (2T) and axisymmetric 4,7-di(thiophen-2-yl)benzo[1,2,5]thiadiazole (DTBT), forming two polymers, P1CIID-2T and P1CIID-DTBT. These polymers exhibit notable differences in backbone linearity and dipole moments, influenced by the symmetry of their donor counterparts. In particular, P1CIID-2T, which contains a centrosymmetric 2T unit, demonstrates a linear backbone and a significant dipole moment of 10.20 D. These properties contribute to the favorable film morphology of P1CIID-2T, characterized by highly ordered crystallinity in the presence of fifth-order (500) X-ray diffraction peaks. Notably, P1CIID-2T exhibits a significant improvement in molecular alignment under dynamic force, resulting in over 8-fold improvement in the performance of organic field-effect transistor (OFET) devices, with superior electron mobility up to 1.22 cm2 V-1 s-1. This study represents the first synthesis of asymmetric monochlorinated isoindigo-based conjugated polymers, highlighting the potential of asymmetric monochlorination for developing n-type semiconducting polymers. Moreover, our findings provide valuable insights into the relationship between the molecular structure and properties.

Output Performance Enhanced Triboelectric Nanogenerators Induced by Magnetic Ink Trapping Property Act as Wearable Sensors.

The demand for clean-energy collection has gradually increased in recent years, making triboelectric nanogenerators a promising research field, because of their advantages in convenient manufacturing, diversified materials, and diverse synthesis and modification possibilities. However, recent studies indicate that charge decay, a major limiting factor in the triboelectric output, prevents the induced charge from combining with the bottom electrode, leading to charge loss. The use of charge-trapping sites to retain the induced charge generated during the friction process is an important solution in the field of triboelectric nanogenerator research. This study proposes the use of an elastic ink with macroscopic magnetism as trapping sites by coating the ink as dots between the polytetrafluoroethylene (PTFE) dielectric layer and the electrode layer. Nickel particles in the magnetic ink are doped into the system as microcapacitors, which prevent the combination of the friction layer and induced charges on the back electrode. Because the nickel itself can be used as a charge-potential trap to capture the charge introduced by the charge-injection process, the charge can be maintained for a long time and achieve a long-term high-output state. The output voltage was more than 6 times that of the reference group without the magnetic-ink coating after 3 h. The results provide a reference direction for research on preventing charge decay and trapping charges in triboelectric nanogenerators.

Detection of Red Pepper Powder Adulteration with Allura Red and Red Pepper Seeds Using Hyperspectral Imaging.

This study used shortwave infrared (SWIR) technology to determine whether red pepper powder was artificially adulterated with Allura Red and red pepper seeds. First, the ratio of red pepper pericarp to seed was adjusted to 100:0 (P100), 75:25 (P75), 50:50 (P50), 25:75 (P25), or 0:100 (P0), and Allura Red was added to the red pepper pericarp/seed mixture at 0.05% (A), 0.1% (B), and 0.15% (C). The results of principal component analysis (PCA) using the L, a, and b values; hue angle; and chroma showed that the pure pericarp powder (P100) was not easily distinguished from some adulterated samples (P50A-C, P75A-C, and P100B,C). Adulterated red pepper powder was detected by applying machine learning techniques, including linear discriminant analysis (LDA), linear support vector machine (LSVM), and k-nearest neighbor (KNN), based on spectra obtained from SWIR (1,000-1,700 nm). Linear discriminant analysis determined adulteration with 100% accuracy when the samples were divided into four categories (acceptable, adulterated by Allura Red, adulterated by seeds, and adulterated by seeds and Allura Red). The application of SWIR technology and machine learning detects adulteration with Allura Red and seeds in red pepper powder.

Enhancing Circularly Polarized Phosphorescence via Integrated Top-Down and Bottom-Up Approach.

In the dynamic domain of chiroptical technologies, it is imperative to engineer emitters endowed with circularly polarized luminescence (CPL) properties. This research demonstrates an advancement by employing a combined top-down and bottom-up strategy for the simultaneous amplification of photoluminescence quantum yield (Φ) and the luminescence dissymmetry factor (glum ). Square-planar Pt(II) complexes form helical assemblies, driven by torsional strain induced by bis(nonyl) chains. Integration of chiral anions leads these assemblies to prefer distinct helical sense. This arrangement activates the metal-metal-to-ligand charge transfer (MMLCT) transition that is CPL-active, with Φ and |glum | observing an upswing contingent on the charge number and aryl substituents in chiral anions. Utilizing the soft-lithographic micromolding in capillaries technique, we could fabricate exquisitely-ordered, one-dimensional co-assemblies to achieve the metrics to Φ of 0.32 and |glum | of 0.13. Finally, our spectroscopic research elucidates the underlying mechanism for the dual amplification, making a significant stride in the advancement of CPL-active emitters.

Amplified Performance of Charge Accumulation and Trapping Induced by Enhancing the Dielectric Constant via the Cyano Group of 3D-Structured Textile for a Triboelectric Multi-Modal Sensor.

To further improve the output performance of triboelectric devices, reducing charge attenuation and loss has become a hot research topic. Particularly, textiles have emerged as one of the promising research directions for triboelectric devices owing to their special internal structure and large specific surface area. In the present work, polyacrylonitrile fibers are fabricated with two distinct structures to provide a higher dielectric constant due to the strong polar properties brought about by higher dipole moment of the CN group. In addition, the complex and closely connected structure of the textile increases specific internal surface area. As a friction layer, the output voltage is shown to increase to 625% of the initial value (from 8 to 60 V) after the application of friction for a short time due to accumulation property. When acting as a trapping layer, the charge loss after injection is effectively prevented due to excellent charge trapping effect. After 24 h, the triboelectric output performance remains at ≈70% of the initial value (decreasing from 320 to 220 V), which is more than 20 times that of the polytetrafluoroethylene film, which decreases from 125 to 19 V. The device is realized for the advanced application of multi-modal sensors.

Long-wave infrared transparent sulfur polymers enabled by symmetric thiol cross-linker.

Infrared (IR) transmissive polymeric materials for optical elements require a balance between their optical properties, including refractive index (n) and IR transparency, and thermal properties such as glass transition temperature (Tg). Achieving both a high refractive index (n) and IR transparency in polymer materials is a very difficult challenge. In particular, there are significant complexities and considerations to obtaining organic materials that transmit in the long-wave infrared (LWIR) region, because of high optical losses due to the IR absorption of the organic molecules. Our differentiated strategy to extend the frontiers of LWIR transparency is to reduce the IR absorption of the organic moieties. The proposed approach synthesized a sulfur copolymer via the inverse vulcanization of 1,3,5-benzenetrithiol (BTT), which has a relatively simple IR absorption because of its symmetric structure, and elemental sulfur, which is mostly IR inactive. This strategy resulted in approximately 1 mm thick windows with an ultrahigh refractive index (nav > 1.9) and high mid-wave infrared (MWIR) and LWIR transmission, without any significant decline in thermal properties. Furthermore, we demonstrated that our IR transmissive material was sufficiently competitive with widely used optical inorganic and polymeric materials.

Effect of Acute Self-Myofascial Release on Pain and Exercise Performance for Cycling Club Members with Iliotibial Band Friction Syndrome.

Cycling is a popular sport, and the cycling population and prevalence of related injuries and diseases increase simultaneously. Iliotibial band friction syndrome is a common chronic overuse injury caused by repetitive knee use in cycling. Self-myofascial release using foam rollers is an effective intervention for this syndrome; however, studies reporting positive results on self-myofascial release in cycling are limited. Therefore, this study investigated the effect of self-myofascial release on pain and iliotibial band flexibility, heart rate, and exercise performance (cadence, power, and record) in adult male cyclists with iliotibial band friction syndrome. We evaluated the pain and exercise ability of the control (n = 11) and self-myofascial release (n = 11) groups before and after cycling twice. Significant differences were observed in the pain scale, the iliotibial band flexibility, and cycling pain and power. The posterior cadence of the self-myofascial release group was 3.2% higher than that of the control group. The control group's record time increased by 74.64 s in the second cycling session compared to the first cycling session, while that of the self-myofascial release group decreased by 30.91 s in the second cycling session compared to the first cycling session. Self-myofascial release is effective in relieving pain and may improve cycling performance by increasing the iliotibial band flexibility.

Effect of Composite Chitosan/Sodium Alginate Gel Coatings on the Quality of Fresh-Cut Purple-Flesh Sweet Potato.

In this study, single-layer coating using chitosan (Ch) and sodium alginate (SA) solutions and their gel coating (ChCSA) formed by layer-by-layer (LbL) electrostatic deposition using calcium chloride (C) as a cross linking agent were prepared to improve storage qualities and shelf-life of fresh-cut purple-flesh sweet potatoes (PFSP). The preservative effects of single-layer coating in comparison with LbL on the quality parameters of fresh-cut PFSP, including color change, weight loss, firmness, microbial analysis, CO2 production, pH, solid content, total anthocyanin content (TAC), and total phenolic content (TPC) were evaluated during 16 days of storage at 5 °C. Uncoated samples were applicable as a control. The result established the effectiveness of coating in reducing microbial proliferation (~2 times), color changes (~3 times), and weight loss (~4 times) with negligible firmness losses after the storage period. In addition, TAC and TPC were better retained in the coated samples than in the uncoated samples. In contrast, quality deterioration was observed in the uncoated fresh cuts, which progressed with storage time. Relatively, gel-coating ChCSA showed superior effects in preserving the quality of fresh-cut PFSP and could be suggested as a commercial method for preserving fresh-cut purple-flesh sweet potato and other similar roots.

Enzymatic Hydrolysis Modifies Emulsifying Properties of Okra Pectin.

Okra pectins (OKPs) with diverse structures obtained by different extraction protocols have been used to study the relationship between their molecular structure and emulsifying properties. A targeted modification of molecular structure offers a more rigorous method for investigating the emulsifying properties of pectins. In this study, three glycoside hydrolases, polygalacturonase (PG), galactanase (GL), and arabinanase (AR), and their combinations, were used to modify the backbone and side-chains of OKP, and the relationships between the pectin structure and emulsion characteristics were examined by multivariate analysis. Enzymatic treatment significantly changed the molecular structure of OKP, as indicated by monosaccharide composition, molecular weight, and structure analysis. GL- and AR- treatments reduced side-chains, while PG-treatment increased side-chain compositions in pectin structure. We compared the performance of hydrolyzed pectins in stabilizing emulsions containing 50% v/v oil-phase and 0.25% w/v pectin. While the emulsions were stabilized by PG (93.3% stability), the emulsion stability was reduced in GL (62.5%), PG+GL+AR (37.0%), and GL+AR (34.0%) after 15-day storage. Furthermore, microscopic observation of the droplets revealed that emulsion destabilization was caused by flocculation and coalescence. Principal component analysis confirmed that neutral sugar side-chains are key for long-term emulsion stabilization and that their structure explains the emulsifying properties of OKP. Our data provide structure-function information applicable to the tailored extraction of OKP with good emulsification performance, which can be used as a natural emulsifier.

Controllable Physical Synergized Triboelectricity, Shape Memory, Self-Healing, and Optical Sensing with Rollable Form Factor by Zn cluster.

To build devices offering users comfortable experience, it is important to focus on form factor and multifunctionality. In this study, for the first time, multifunctional Zn clusters with shape memory, self-healing, triboelectricity, and optical sensing synergized with rollable form factor are designed and fabricated by coordinating COO- and Zn2+ . As pore forming agent, Zn clusters produce hierarchical porous structure depending on Zn amount. Zn clusters are applied as message transmitters and charge containers in optical sensing and corona charge injection, respectively. Moreover, Zn clusters in PVB-COO-Zn serve as positive tribomaterial due to Zn ion doping effect, increasing the output performance as the Zn amount reaches 20 wt%. In addition, injecting positive charge into PVB-COO-Zn 20 lead to more than 24 times increase in output performance compared to those of non-porous structures. The reversibility of Zn clusters endows shape memory and self-healing, synergized with the rollable form factor. The rollability is implemented using the long alkyl chain and the energy absorption of porous structure, providing damage resistance. The advancements in this work provide opportunities for multifunctional and unique applications (shape memory rotating-triboelectric nanogenerator, rollable self-healing touchpad, hidden tag) synergized with rollability that accomplishes working in broadened condition in near future.

Strain-durable dark current in near-infrared organic photodetectors for skin-conformal photoplethysmographic sensors.

Sensitive detection of near-infrared (NIR) light is applicable to variety of optical, chemical, and biomedical sensors. Of these diverse applications, NIR photodetectors have been used as a key component for photoplethysmography (PPG) sensors. In particular, because NIR organic photodetectors (OPDs) enable fabrication of stretchable and skin-conformal PPG sensors, they are attaining tremendously increasing interest in both academia and industry. Herein, we report strain-durable and highly sensitive NIR OPDs using an organic bulk heterojunction (BHJ) layer. For effective suppression of dark current, we employed BHJ combination consisting of PTB7-Th:Y6 which forms high energy barrier against transport-injected holes. The optimized OPDs exhibited high specific detectivity up to 2.2 × 1012 Jones at 800 nm. By constructing the devices on the parylene substrates, we successfully demonstrated stretchable NIR OPDs and high-performance skin-conformal PPG sensors.

Controllable Triboelectric Series Using Gradient Positive and Negative Charge-Confinement Layer with Different Particle Sizes of Mesoporous Carbon Materials.

As a method to maximize the energy efficiency of triboelectric nanogenerators (TENGs), high-voltage charge injection (HVCI) on the surface is a simple and effective method for increasing surface charge densities. In this study, positive and negative triboelectric series are controlled using a 3-layer gradient charge-confinement wherein the particle sizes of the mesoporous carbon spheres (mCSs) are sequentially arranged depending on the external surface area of the mCSs. In the gradient charge-confinement layers of this study, the mCS with different sizes perform charge transport from the surface to a deep position during HVCI while mitigating the charge loss through charge confinement to induce the high space charge densities. Through this process, the output voltage-which is initially 15.2 V-is measured to be 600 V after HVCI, thus representing an increase of about 40 times. Further, to amplify the low output current, which is a disadvantage of triboelectric energy, two types of electrical energy-triboelectric and electromagnetic energy-are produced in single mechanical motion. As a result, the output current produced by the cylindrical TENG and electromagnetic generator is recorded as being 1300 times higher, increasing from 12.8 µA to 17.5 mA.

Facile Strategy for Modulating the Nanoporous Structure of Ultrathin π-Conjugated Polymer Films for High-Performance Gas Sensors.

Conventional conjugated polymer (CP) films based on organic field-effect transistors (OFETs) tend to limit the performance of gas sensors owing to restricted analyte diffusion and limited interactions with the charge carriers that accumulate in the first few monolayers of the CP film in contact with the dielectric layer. Herein, a facile strategy is presented for modulating the morphology and charge-transport properties of nanoporous CP films using shearing-assisted phase separation of polymer blends for fabricating OFET-based chemical sensors. This approach enables the formation of nanoporous films with pore size and thickness in the ranges of 90-550 and 7-27 nm, respectively, which can be controlled simply by varying the shear rate. The resulting OFET sensors exhibit excellent sensing performance when exposed to NH3 gas, demonstrating a high responsivity (≈70.7%) at 10 ppm and good selectivity toward NH3 over various organic solvent vapors. After a comprehensive analysis of the morphology and electrical properties of the CP films, it is concluded that morphological features, such as film thickness and surface area, affect the sensing performance of nanoporous-film-based OFET sensors more significantly compared to the charge-transport characteristics of the films.

Quinoidal Small Molecule Containing Ring-Extended Termini for Organic Field-Effect Transistors.

In this work, we synthesized and characterized two quinoidal small molecules based on benzothiophene modified and original isatin terminal units, benzothiophene quinoidal thiophene (BzTQuT) and quinoidal thiophene (QuT), respectively, to investigate the effect of introducing a fused ring into the termini of quinoidal molecules. Extending the terminal unit of the quinoidal molecule affected the extension of π-electron delocalization and decreased the bond length alternation, which led to the downshifting of the collective Raman band and dramatically lowering the band gap. Organic field-effect transistor (OFET) devices in neat BzTQuT films showed p-type transport behavior with low hole mobility, which was ascribed to the unsuitable film morphology for charge transport. By blending with an amorphous insulating polymer, polystyrene, and poly(2-vinylnaphthalene), an OFET based on a BzTQuT film annealed at 150 °C exhibited improved mobility up to 0.09 cm2 V-1 s-1. This work successfully demonstrated that the extension of terminal groups into the quinoidal structure should be an effective strategy for constructing narrow band gap and high charge transporting organic semiconductors.

Wearable Strain Sensors with Aligned Macro Carbon Cracks Using a Two-Dimensional Triaxial-Braided Fabric Structure for Monitoring Human Health.

Recently, wearable sensors, due to their ability to exhibit characteristics, have been appealing for health monitoring through detection of human motions and vital signals. The development of strain sensors with high sensing performance and wearability has been a great challenge to date. In this study, a textile-based strain sensor with good skin affinity was fabricated through a simple fabrication process of dip-coating 2D triaxial-braided fabrics using carbon ink and then drying. The macro crack aligned on the 2D triaxial-braided fabric with a high-density structure and good recovery force. The sensitivity of textile-based strain sensor can be enhanced due to aligned macro crack formed by prestrained fabricating process and characteristic of the 2D triaxial braided fabric with high dense structure. The optimized sensor exhibits high sensitivity (gauge factor: 128) in a strain range of 0-30%, durability (5000 cycles), washability, low hysteresis, and fast response time (90 ms). Therefore, it can be applied as a wearable sensor that can monitor human motions (large strain) and biosignals (subtle strain).

Anti-glycation effect of Ecklonia cava polysaccharides extracted by combined ultrasound and enzyme-assisted extraction.

The anti-glycation effects of polysaccharides from Ecklonia cava were examined according to extraction method-hot buffer (HP), ultrasound (UP), enzyme (EP), or a combination of ultrasound and enzyme (UEP). The physicochemical properties, monosaccharide compositions, and structural characteristics of the polysaccharides were determined. UP, EP, and UEP had higher fucose and galactose compositions than HP. The FT-IR spectra of samples showed the presence of sulfate esters and 4-sulfate galactose. 1H NMR indicated that alginate was removed by purification. UP, EP, and UEP possessed higher sulfate contents than HP. UEP presented with the highest extraction yield and lowest protein and uronic acid contents. The levels of AGE formation, as well as fructosamine, α-dicarbonyl, and protein carbonyl contents were determined during a 3-week incubation in a BSA/fructose system. UEP and UP effectively inhibited AGE, although the inhibition effect was lower than that of aminoguanidine. However, UP and UEP showed higher inhibition of fructosamine, α-dicarbonyl, and protein carbonyl than aminoguanidine. AGE formation was negatively correlated with sulfate content and some monosaccharide compositions (fucose, galactose, and glucose), but positively correlated with molecular weight. Overall, the present study suggests that UEP is a suitable extraction method for obtaining anti-glycation agents from E. cava.

Vertically and Horizontally Drawing Formation of Graphite Pencil Electrodes on Paper by Frictional Sliding for a Disposable and Foldable Electronic Device.

The objective of this study is to fabricate an electrode by frictional sliding caused by a rough paper surface. The pressure exerted during drawing induces adsorption of the graphite particles by the rough paper and simultaneously reduces the surface roughness of the paper electrode. Repetitive drawing in one-way direction reduced the roughness of the paper surface, decreasing the grain boundaries of graphite. This increases the electron pathway at the electrode, thus reducing the resistance to less than 50 Ω. At the same time, repetitive drawing could confirm that unstable errors caused by the hand could help converge within a certain margin of error. We quantified the relationship between pressure and resistance when drawing on the electrode using a pencil hardness tester. In addition, the electrodes formed by repeated drawing generated a new surface grain and boundary, parallel to the drawing direction, and changed the electrode characteristics with respect to the drawing direction. The grain boundary difference based on the drawing direction was measured via a heating test of the foldable device, a sound pressure level, and laser scattering vibrometer measurements of a linear speaker. The fabricated graphite electrodes can be used in disposable foldable paper electronics because they are prepared using inexpensive materials.