Table of Content

10 April 2025, Volume 33 Issue 04

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Research progress of textile materials with negative Poisson's ratio

YANG Ruihua, HUA Yuzhu

2025, 33(04):  1-12. 

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Textile materials with negative Poisson's ratio structures have excellent shear resistance, energy absorption, and fracture resistance, and they are cost-effective compared to other materials with negative Poisson's ratio structures. Therefore, the auxetic textile materials have aroused the interest of many scholars. To further promote the research and application of textile materials with negative Poisson's ratio, this article systematically introduces the different auxetic principles of one-dimensional, two-dimensional, and three-dimensional auxetic textile materials and summarizes their existing problems. 
The research on auxetic yarns with a negative Poisson's ratio is based on the helical structure core-spun yarn, and the auxetic effect is achieved by the position exchange between components in the yarn. Its production equipment mainly includes ring spinning machines, weaving machines, hollow spindle, or simple wrapping mechanisms. Due to the influence of the helical structure, the end of the auxetic yarns is prone to untwisting and deformation, resulting in the loss of the auxetic effect. To solving this problem, it is necessary to develop more novel structures and preparation methods. There are two main ways for two-dimensional fabrics to produce auxetic effects: one is to weave fabrics with yarns with a negative Poisson's ratio; the other is to use ordinary yarns and choose appropriate yarn arrangement to weave two-dimensional fabrics with negative Poisson's ratio effect. As the yarn with a negative Poisson's ratio needs to be arranged straight in the fabric to produce a good auxetic effect, it is only applied in auxetic woven fabrics. In addition, knitted fabrics can achieve different negative Poisson's ratio structures through flexible yarn arrangement. The negative Poisson's ratio structures formed are mostly concave and rotating structures. Therefore, when designing and manufacturing two-dimensional fabrics with a negative Poisson's ratio, it is necessary to carefully consider and evaluate factors such as yarn properties and fabric structure design in order to develop optimal auxetic performance for the textile materials. Three-dimensional fabrics are very popular in composite materials, and the addition of auxetic effect further improves the mechanical properties and energy absorption performance of 3D fabrics. Different from the previous two textile materials, three-dimensional auxetic fabrics can produce auxetic effects both inside and outside the plane. Warp knitted three-dimensional auxetic fabrics typically use concave and rotating structures; the three-dimensional auxetic knitted fabric is mainly characterized by the folding structure; the three-dimensional woven auxetic fabric utilizes binder yarns to form a negative Poisson's ratio structure. 
In recent years, despite the numerous studies on negative Poisson's ratio textile materials and their extensive potential applications, the exploration of these materials has remained focused on the basic protective properties. Few studies have successfully combined their advantages with other fields and put them into practical use. In addition, integrating the advantages of negative Poisson's ratio textiles into practical production for rational product design is also a bottleneck that needs to be overcome. For example, if special properties such as self-driving, sensing, and thermal management can be endowed to auxetic textiles, it will greatly broaden their development path. In summary, the development of auxetic textiles should focus on exploring new application areas and practical applications.


Research progress on low-salt and salt-free dyeing of cellulose fiber with reactive dyes

ZHANG Hongjuan, WANG Huiqiang, SHEN Chuliang, WANG Jiping, CAO Jingpei

2025, 33(04):  13-25. 

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When dyeing cotton fibers with reactive dyes in the traditional water bath system, a large number of neutral inorganic salts need to be added to address the charge repulsion between the dye anions and the fibers in order to improve the reactive dye utilization. At the same time, a large amount of alkali must be used to ensure that the reactive dye can fully covalently bond with the fibers. However, the large amount of inorganic salts will lead to super high salt content in the dyeing wastewater, which increases the difficulty and cost of post-processing. At the same time, inorganic salt has brought a great threat to the ecological environment and water resources. Therefore, the low-salt and salt-free dyeing technology has become a hot spot in the current printing and dyeing industry. In order to realize the clean dyeing process of cellulose fibers with water saving, energy saving, high efficiency and ecological protection, researchers have done a lot of work. 
In this paper, the problems and limitations in the development of low-salt and salt-free dyeing technology were summarized from the development of new dye molecular structure (original structure modification and cationic reactive dyes), multi-functional substitute salts development and application, low-salt dyeing additives, cellulose modification, and non-aqueous medium dyeing technology. For the traditional water bath system, the modification of the reactive group, water-soluble group or chromophore on the structure of the existing reactive dyes, or the redevelopment of cationic reactive dyes, all have the problems of high cost, few categories, and incomplete chromatography. It is very low to realize salt-free and low-salt dyeing process as well as water saving and emission reduction by using other organic substitute salt, or crosslinking agent. Although widely studied cationic modification technology of cotton fabrics can reduce the dosage of inorganic salts, cationic modification and dyeing cannot be carried out in the same bath. This process requires pre-treatment of cotton fabrics, which has the problem of long process, high production cost, and difficulty in controlling the dyeing evenness. In addition, small bath ratio, electrochemical dyeing, and suspension dyeing have high requirements for dyes and poor universality. As for the new non-aqueous medium dyeing technology, the medium used in the early reported organic solvent dyeing technology is highly toxic and difficult to recover. While, the most reported supercritical CO2 dyeing cannot make cotton fibers swell, resulting in low dye adsorption rate and dyeing depth. In addition, the dyeing process needs to be completed under ultra-high pressure, which has the problems of low operational safety and high equipment cost. 
At present, the non-aqueous medium dyeing technology using high boiling point D5 as the medium has achieved remarkable results. But this technology also needs special dyeing equipment (dyeing, recycling, etc.) in the early stage, and the investment cost is high. Therefore, it is imperative to develop an economical, universal, water-saving, and emission-reducing non-aqueous medium dyeing technology in the future.


Structural optimization and numerical simulation of nozzles for foreign fiber sorters

SUN Jian, LAN Lan, WANG Tong, HAN Zixu, LIN He, CHENG Xiaole

2025, 33(04):  26-32. 

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Cotton is one of the important raw materials in the textile industry. After processing, it is used to manufacture various textile products. The presence of foreign fibers in cotton can have an impact on the quality of the finished yarn, the fabric surface effect, the performance and the subsequent process treatment. Therefore, in the textile production process, it is necessary to effectively screen, separate, or control foreign fibers in the raw materials to ensure that the quality and performance of the final products meet the expected requirements. The cotton foreign fiber sorting machine effectively separates foreign fibers and impurities through high-speed rotating brush rollers, airflow and vibration. However, there is still room for improvement in terms of foreign fiber detection rate, energy consumption, and rejection rate. As a key component in the foreign fiber sorting process, the reasonable design of the reject nozzle structure is crucial to the efficiency and accuracy of the foreign fiber sorting machine.
The nozzle is critical to ensuring fiber quality and maintaining production efficiency by providing precise positioning, efficient rejection, continuous production, and reduced human intervention during foreign fiber rejection. By applying high-pressure airflow, the nozzle can quickly and accurately remove foreign fibers from the fibers, ensuring smooth operation of the production line, improving production efficiency, and reducing production costs. Therefore, optimizing the nozzle structure to reduce energy consumption and improve rejection rate is necessary. The Laval nozzle is a specially designed nozzle commonly used in rocket engines, jet engines, and other fields that require high-speed airflow. In practical use, the Laval nozzle can accelerate the gas from subsonic to supersonic speeds, achieving the effect of gas acceleration while improving efficiency, controlling flow rate, reducing backpressure effects, avoiding equipment overheating, and simplifying the structure. Therefore, the unique shape and functionality of the Laval nozzle provide reference for the optimization design of the rejection nozzle structure.
In summary, in this study, we aim to optimize the structure of the rejection nozzle in the cotton foreign fiber sorting machine based on the characteristics of the Laval nozzle's contraction-expansion design. Numerical simulation is used to analyze the external flow field characteristics of the nozzle before and after optimization. By comparing the changes in velocity, pressure, and air consumption, the feasibility of the optimization design is validated to provide theoretical reference for the practical application of the nozzle, so as to achieve the goal of improving the performance of the whole machine by realizing the efficient removal of foreign fibers.


Optimization of hot pressing process for e-PTFE film laminated composite fabrics using response surface methodology

SONG Liwei , JIN Xiaoke, MIAO Yongda, LIU Xinyu, ZHU Chengyan, TIAN Wei

2025, 33(04):  33-42. 

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Nowadays, people mostly rely on air conditioners to maintain their thermal and moisture balance indoors. This method not only consumes a lot of energy, but also cannot meet the thermal and moisture comfort of the human body in outdoor environments. As a new type of functional textile, thermal and moisture management fabrics can effectively solve this problem. Currently, fabrics for thermal and moisture management are mainly used in hot environments, while there is little research on fabrics for use in cold environments, especially in winter outdoor sports. Thermal and moisture management fabrics should have two properties: on the one hand, they should be able to timely evacuate sweat generated by the human body, and on the other hand, they should have windproof performance. Therefore, laminated composite fabrics made with e-PTFE films that possess windproof, waterproof, and moisture-permeable properties have become a popular choice.
To address the issue of fabricating fabrics with thermal and moisture management capabilities for winter outdoor sports, this paper mainly studies the hot pressing process of e-PTFE film laminated composite fabrics. A green and environmentally friendly PA hot melt adhesive film, which exhibits relatively uniform colloidal properties, is selected as the adhesive, and e-PTFE film serves as the intermediate functional film. Firstly, a single factor experiment was conducted to investigate the effects of hot pressing time, temperature, pressure, and adhesive amount on the properties of e-PTFE film laminated composite fabrics in the hot pressing process. The air permeability of the prepared e-PTFE film laminated composite fabrics was≤10 mm/s, indicating windproof performance. Moreover, with the increase of hot pressing time and temperature, the air permeability and peeling strength of the laminated composite fabrics showed a trend of first increasing and then decreasing; as the hot pressing pressure increased, the moisture permeability and peel strength of the fabric gradually decreased; as the amount of adhesive applied increased, the moisture permeability of the fabric gradually decreased, while the peeling strength increased instead. By analyzing the properties of e-PTFE film laminated composite fabrics, the ranges of hot pressing time, temperature, and adhesive amount were determined to be 10‒20 s, 140‒160 ℃, 5‒15 g/m2, and the hot pressing pressure was determined to be 0.5 MPa. Afterwards, a three-factor three-level response surface experiment was designed using the Box Behnken response surface methodology to obtain analysis of variance tables and response surface graphs. From the response surface graphs, it can be seen that the interaction between hot pressing time, temperature, and adhesive amount had a significant impact on moisture permeability and peel strength. Thus, the optimal hot pressing process for e-PTFE film laminated composite fabric was obtained, with a hot pressing time of 15 seconds, a hot pressing temperature of 150 ℃, an adhesive amount of 10 g/m2, and a hot pressing pressure of 0.5 MPa; the air permeability of the e-PTFE film laminated composite fabric obtained under this process condition was 1.96 mm/s, the moisture permeability was 5670.60 g/(m2·24h), and the peeling strength was 2.63 N.
This paper studies the relationship between the hot pressing process parameters and the wind resistance, moisture permeability, and peeling strength of e-PTFE film laminated composite fabrics through response surface methodology, and obtains the optimal hot pressing process. At the same time, it lays the foundation for the subsequent use of hot pressing methods to prepare thermal and moisture management fabrics suitable for winter. These research results also provide reference for the preparation of laminated composite fabrics using e-PTFE films in the future.


Effects of laser engraving on fabric structure and transmittance

MIAO Yongda, JIN Xiaoke, TIAN Wei, DING Hao, ZHU Chengyan

2025, 33(04):  43-51. 

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Laser engraving stands as a significant material processing technology, widely employed in the textile and apparel industries due to its distinctive advantages of ease of manipulation, high precision, and cost-effectiveness. Currently, research on laser engraving in household textiles has garnered significant attention, curtains are a crucial component of household textiles, and through laser engraving, they can exhibit a multi-layered three-dimensional effect, thereby enhancing the visual appeal of the indoor environment. However, the high-temperature etching effect during laser engraving may cause penetrating damage to the fabric, thereby impacting the visual privacy of curtain fabrics, which is commonly characterized by transmittance.
To analyze the influence of laser engraving on the structure and transmittance of the fabric, this paper uses different laser engraving parameter combinations (laser power of 3 W, 6 W, 9 W, 12 W, 15 W and 18 W, and laser speed of 500 mm/s, 400 mm/s, 300 mm/s and 200 mm/s) to process cotton and polyester fabrics. First, through microscopic morphological observation using an electron microscope, it was found that the cotton fabric, under the effect of laser thermal energy, exhibited expansion, rupture, and even vaporization removal. The cotton fibers were charred and fell off, yarn cohesion disintegrated, and the interlaced structure of the fabric became looser. The polyester fabric, on the other hand, underwent melting, flowing, and even vaporization decomposition. The fabric surface transitioned from scattered granular polyester to connected bulk polyester, accompanied by fine cracks. On the other hand, the polyester fabric underwent melting and flow, even vaporization and decomposition, with the fabric's surface transitioning from scattered granules of polyester to bonded blocks of polyester accompanied by fine cracks. Following this, Image J software was utilized to standardize the pores at the penetration points of the fabric's transmitted grayscale images for porosity calculation. The number of pores and porosity rate on cotton and polyester fabrics are positively correlated with the laser engraving energy. The transmitted grayscale images showed that the pores in the cotton fabric after laser engraving were approximately shaped like water droplets or ellipses, while those in the polyester fabric were mostly irregular. Both types of pores appeared at the intersections of warp and weft threads. As the laser engraving energy increased, the thickness of the cotton fabric decreased, and the thickness of the polyester fabric initially increased and then decreased, mainly due to the polyester becoming more rigid and harder to compress after laser engraving. Finally, the influencing factors of fabric transmittance after laser engraving were investigated using the gray relational analysis method and correlation theory, and the porosity rate after laser engraving was the primary factor influencing the fabric's transmittance, showing a highly significant positive correlation. The fabric thickness, on the other hand, had an extremely significant negative correlation with the fabric's transmittance.
This study analyzes the action mechanism of laser on fabrics, explores the effects of laser engraving parameters on the structure of fabrics, and studies the relationship among laser mechanism, fabric structure, and transmittance. The findings of this study can serve as reference for the application of laser engraving technology in textiles such as curtains.


Optimization of pigment extraction process from silk fabrics dyed with pagoda tree buds

WANG Shansen, YAO Mingyi, WANG Ruqian, GUO Danhua, LIU Jian,

2025, 33(04):  52-59. 

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"Huaimi", refering to the buds of pagoda tree (Styphnolobium japonicum), is native to China, and currently mainly distributed in North China and the Loess Plateau region. During the Ming and Qing dynasties, it was widely used as a dye in textile dyeing. The buds of pagoda tree are rich in flavonoids, such as rutin and quercetin, and the main active ingredient is rutin. In order to obtain a bright yellow color, ancient dyers usually boiled or fried buds of pagoda tree at high temperatures. This process prevents rutin from being hydrolyzed into quercetin, thereby  rendering the dyed color on fabrics more vibrant. In ancient China, yellow was always closely associated with imperial authority, symbolizing supreme authority and being one of the most revered colors by the ancients. Therefore, yellow dyes are often detected in ancient textiles, and buds of pagoda tree is one of the common dyes. Before using detection techniques to analyze textile dyes, it is necessary to extract and peel the dyes from the textiles. So selecting an appropriate extraction method is particularly important. There are various methods for extracting dyes from silk fabrics, among which the most widely used is heating with hydrochloric acid. However, this method easily hydrolyzes the glycoside components in the dyes, resulting in the loss of information sources related to the dyes, especially for flavonoid dyes as most of them contain many glycoside compounds. Therefore, it is important to use appropriate extraction methods to obtain more information about the dyes.
This article aims to explore the extraction method and process optimization for silk fabrics dyed with buds of pagoda tree. Two extraction methods were used: pyridine (pyridine aqueous solution/0.5 mol/L moxalic acid) and methanol(10 mmol/L ethylenediaminetetraacetic acid disodium/acetonitrile/methanol aqueous solution). The pigments were extracted by heating and nitrogen blowing. Single-factor experiments were designed and conducted to screen three factors affecting extraction: temperature, time, and solvent volume fraction. Furthermore, the extraction process was optimized using the response surface method (RSM).
The results showed that the optimal process conditions for the pyridine extraction method were an extraction temperature of 56.9 ℃, an extraction time of 29.6 min, and a pyridine volume fraction of 42.2 %. The predicted and actual optimal absorbance values were consistent, at 0.940 and 0.939, respectively. For the methanol extraction method, the optimal process conditions were  an extraction temperature of 61.6 ℃, an extraction time of 25.9 min, and a methanol volume fraction of 49.6%. The predicted and actual optimal absorbance values were also consistent, at 0.784 and 0.780, respectively. RSM provides a simple and reliable optimization method for dye extraction. The pyridine and methanol extraction methods can obtain the main dye components and glycoside compounds of buds of pagoda tree, which can provide more compound information. This experiment can provide reference for the extraction of buds of pagoda tree and other flavonoid dyes from silk fabrics.


Clean dyeing process of cationic polyester blended fabrics based on a response surface method

ZHOU Shihang, CHEN Yangyi, WANG Ruya, YE Xiaorou

2025, 33(04):  60-67. 

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The polyester fiber is the largest variety of synthetic fibers in the world, which occupies a very important position in the field of textile and garment. With the improvement of people's living standards, people have also put forward new requirements for polyester blended fabrics, paying more attention to their comfort and functionality. Compared with ordinary polyester, cationic (dyeable) polyester has a softer texture than ordinary polyester, and has a certain hydrophilicity and unique two-color effect. However, in the dyeing process, the energy consumption and water consumption are high, and the production efficiency is low. The wastewater is not conducive to direct discharge, and the wastewater has high color, unstable pH, organic pollutants and high content of refractory components, resulting in a large number of wastewater and wastewater recovery. In addition, the use of various additives increases the difficulty of subsequent fabric cleaning, and the dyeing process is cumbersome and not environmentally friendly, which limits its further industrial development. To explore the dyeing process of cationic polyester blended fabrics, the response surface method (RSM) was used to optimize the process of cationic dyeable polyester, with decamethylcyclopentasiloxane (D5) as the medium and K/S value as the corresponding value. The main factors affecting the dyeing process of cationic dyeable polyester were screened by Plackett-Berman experiment through the influence of single factors on the dyeing process, such as dye dosage, D5 dosage and dyeing time. P value less than 0.05 was considered to have a significant impact on this factor, and p value less than 0.01 was considered to have an extremely significant impact on this factor. According to the p value, it was found that the dyeing temperature was the biggest factor affecting the K/S value, followed by the amount of dye and the amount of D5. On this basis, three factors having a significant effect on the color depth value were selected, and the response surface method (RSM) was established by using the central composite design (CCD) method. The response surface results were obtained and analyzed. On this basis, the influence of the interaction between various factors on the K/S value of cationic polyester blended fabrics was carried out. In summary, the K/S value was used as the response surface to establish the dyeing process optimization of cationic polyester blended fabrics, and the difference of the obtained response surface model was compared. The results show that the optimum dye dosage of cationic polyester blended fabrics is 1.6% (o.w.f), the dosage of D5 is 93.5%, the dyeing time is 60 min, and the dyeing temperature is 108 °C. The dyeing results show that the K/S value can be increased by increasing the amount of D5 and dyeing temperature, and the dyeing time should not exceed 60 min. RSM experiment predicts the optimal process of cationic polyester blended fabrics. According to this process, the parallel test is carried out, and the comparison error is less than 0.2. It shows that the verification results are basically consistent with the predicted values, which can more accurately reflect the depth of color change. It can fully describe the relationship between the influencing factors of cationic polyester blended fabrics' dyeing conditions and the dyeing results. It shows that the model design is reasonable, stable and reliable. In addition, the color fastness test results of the fabric show that the dyed fabric has good washing resistance, friction resistance and light fastness, all of which are above four levels. RSM provides a simple and effective method to optimize acorn dyeing process. This study provides useful reference for the clean dyeing of cationic polyester blended fabrics

Effect of washing conditions on the performance of coated smart fabrics

GUO Jinxia, SONG Yi, WEI Yuhui, LING Xu, PAN Wei

2025, 33(04):  68-74. 

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With the rapid development of science and technology, smart fabrics, as an emerging textile material, have gradually become the research focus of academia and industry, and have affected fields such as health, medical treatment, military, and commerce. The application of coating finishing technology is pivotal in realizing the functionality of smart textiles. However, there are relatively few related studies on the washing of smart fabrics, which mainly focus on the types of coatings, the current status of fabrics, and the performance evaluation after washing. This study aims to systematically investigate the effects of various washing methods and parameters on the durability of smart textiles and assess the changes in performance through testing before and after washing.
 With nano-silver coated pure cotton smart fabrics as the research subject, the article designed various washing methods and different washing parameters. Three coating finishing processes were adopted: immersion-rolling-drying method, liquid-phase chemical reduction method, and immersion method. The washing methods include washing in a washing machine, combined washing using a washing machine with micro-nano bubbles, and ultrasonic washing. In terms of washing parameters: for coating finishing process c (immersion method), ultrasonic washing was performed at room temperature for 5, 10, and 15 times, respectively, with a main washing time of 20 minutes; the main washing time was set to 20, 30, and 40 minutes for one washing. The remaining parameters were set to a detergent concentration of 2.0 g/L, a rinsing time of 15 minutes, and air-drying at room temperature after washing.
Throughout the experiment, the performance of the smart fabrics before and after washing was evaluated, including water repellency, shrinkage, morphological characteristics, and electrical conductivity indicators. Comparative analysis reveals significant differences in the effects of various washing methods and parameters on the performance of smart fabrics. The results indicate that the washing method combining washing machines with micro-nano bubbles has the most significant damage to the silver coating, while the ultrasonic washing effectively reduces damage to the coating surface through cavitation effects. As the number of washes and main wash times increase, the stability of the silver coating shows a decreasing trend. In terms of electrical conductivity, ultrasonic washing maintains a lower change in resistance value, effectively preserving the integrity of the coating, whereas other washing methods result in significant fluctuations in resistance values. Regarding shrinkage, ultrasonic washing treatment shows superior dimensional stability, while the washing method combining washing machines with micro-nano bubbles results in noticeable changes in dimensional stability, particularly for textiles treated with the immersion method, which exhibits relatively smaller changes in dimensional stability due to thorough modification. Concerning water repellency, the effects of different washing methods on the textiles are not significant.
In conclusion, ultrasonic washing is advantageous in protecting the performance of silver-coated textiles, making it the preferred method for handling such textiles. The optimal washing conditions are as follows: using ultrasonic washing at a temperature of (20±2) °C, with one wash cycle, a main washing time of 20 minutes, two rinses, a main wash bath ratio of 1:40, a rinse bath ratio of 1:50, and a detergent dosage of 2 g/L. The findings of this study provide theoretical references for the design of washing procedures for smart fabrics, enrich the theory of clothing washing, and facilitate the further development of research and applications in the field of smart fabrics.


Numerical simulation of the fluid flow pattern in slot die coating process

HONG Haobin, ZHANG Hengkuan, ZHANG Xianming

2025, 33(04):  75-82. 

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The slot die coating is widely utilized in fabric coating and advanced packaging as a predictive coating technology. The thickness distribution and stability of the liquid film formed during the slot die coating process affect the morphology and structure of the cured coating, ultimately influencing the properties of the product. However, due to the coupling of multiple operational parameters, the mechanism that influences film thickness distribution and stability remains unclear.
In this study, we conduct numerical simulations of the slot die coating process to investigate film formation. Firstly, relevant governing equations are established, the geometric model and boundary conditions are determined and meshed, the solution method is given and mesh-independence is verified. Subsequently, we verify the accuracy of our numerical simulations by comparing them with experimental data reported in the literature. Finally, we investigate the mechanisms through which operating conditions and fluid properties influence the thickness, uniformity, and stability of the liquid film.
The contour plots of liquid phase distribution shows that the thickness of the liquid film increases continuously with the elongation of fluid flow time. When the flow time is 0.1s, the liquid film thickness no longer changes with time, and the transient numerical calculation is completed. To investigate the coating mechanism and flow pattern of slot die coating, different substrate moving speeds, inlet velocities and fluids with different viscosities are set up for numerical calculation, and the role of each factor is analyzed in combination with the film thickness distribution and film-forming stability. It can be concluded from the film thickness distribution graph and velocity contour that: when the substrate moving speed is relatively low, the film-forming flow rate is less than the inlet flow rate, resulting in fluid accumulation at the die lip. Thus the film-forming flow rate and the liquid film thickness increase with the substrate moving speed; when the film-forming flow rate increases to the inlet flow rate, the liquid film thickness reaches the maximum. However, as the substrate moving speed further increases, the film-forming flow rate remains constant and equal to the inlet flow rate, leading to a decrease in liquid film thickness. Within the stable operating window, coating uniformity increases with the increase of the substrate moving speed. As the viscosity of the fluid increases, there is little noticeable change in the thickness of the coating, whereas the uniformity of the liquid film steadily decreases. This is attributed to the increased viscous force, which causes the substrate to entrain more fluid. Consequently, the film-forming flow rate equals the inlet flow rate, resulting in no further changes in film thickness. As the inlet velocity increases, the thickness of the liquid film keeps increasing and the uniformity of the liquid film does not change significantly. The simulation results show that the substrate velocity and inlet velocity are the main factors influencing the film thickness and its uniformity. A stable and uniform coating can only be achieved within a specific range of process parameters; otherwise, coating defects may arise. The analysis of the film formation mechanism of slot die coating provides theoretical guidance for the optimization of coating process parameters.


Construction of a 3D model of female waist, abdomen and hip based on piecewise fitting mapping

LIN Xiyan, JIANG Lixia, ZHANG Qianyun, LI Tao, ZOU Fengyuan

2025, 33(04):  83-91. 

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In constructing 3D models of female body based on 2D photos, the complexity and diversity of the waist-abdomen-hip region should be taken into account, which is important for the accuracy of a reconstructed 3D model. Therefore, a piecewise fitting mapping model construction method is proposed in this paper to improve the accuracy of the mapping model between 2D contour features and 3D feature indexes.
In this paper, 3D point cloud data of 120 young women aged 18‒25 years were collected, and 15-layer feature sections and radial distance were extracted as 3D feature parameters. At the same time, six contour feature parameters were extracted from the front and side photos of human body. On the basis of correlation analysis, a piecewise mapping model was established to realize the mapping from 2D contour feature to 3D feature index. Then, trigonometric function was used to convert radial distance into discrete point cloud data. Finally, the idea of point-line-plane modeling was introduced to build the 3D model of waist, abdomen and hip.
In this paper, the model reconstruction error was used as the evaluation criterion to determine the optimal configuration of the layer number of feature section. When the number of feature layers was 15, the reconstruction error was not only reduced to 6.45 mm, but also the balance between the model complexity and the error value was achieved. In view of the diversity and complexity of female waist, abdomen and hip, this paper analyzed the correlation between the radial distance and the corresponding width and thickness, aiming to further improve the accuracy of the prediction model. In order to enhance the correlation of some feature points, the method of piecewise mapping was adopted in this paper, and the correlation coefficient of more than half of the samples was raised to the level of more than 0.85. On this basis, 100 samples were randomly selected as training sets, and a regression mapping model with width and thickness as independent variables and radial distance as dependent variables was constructed. To verify the prediction accuracy of the model, the remaining 20 samples were used as test sets for verification. The results show that the error of the mapping model is controlled within -1.5‒2.5 mm. Further, this paper used trigonometric function to carry out point cloud processing of radial distance set, and followed the idea of point-line-plane modeling to realize the reconstruction of female waist-abdomen-hip 3D model. By comparing the reconstructed model with the actual model, it is found that the maximum error percentage of the proposed method is limited to less than 3%.
The 3D human body modeling method based on 2D photo feature point mapping is particularly effective for complex female body types, and its core lies in the accurate positioning and mapping of feature points to build high-precision 3D models. The piecewise fitting technique further optimizes this process and significantly improves the correlation between 2D profile and 3D section parameters. Segmented mapping can refine the modeling for different parts of the body and improve the reconstruction accuracy. 


Research progress on fabric-based wearable ECG electrodes

HOU Jinli, ZHENG Junjie, WANG Chenxiao, Xiong Fan, YANG Chaoran, LI Yunfei, FAN Mengzhao

2025, 33(04):  92-104. 

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The initial use of ECG recordings involved opaque carbon electrodes. With the development of magnetic resonance imaging (MRI), carbon fiber electrodes were introduced to reduce image distortion while simultaneously recording ECG and thoracic impedance. Advances in wearable technology have driven the development of novel ECG electrodes based on textile substrates, which combine nanomaterials and wireless systems to achieve high-quality signal acquisition. The application of new materials, such as gecko-inspired conductive dry adhesives and 3D-printed electrodes, has made ECG monitoring more reliable in various environments. Additionally, innovative electrode technologies, such as stretchable conductive fabrics, electrogel electrodes, hydrogel electrodes, fabric microneedle electrodes, and polymer conductive adhesives , have begun to emerge.
Selecting suitable conductive materials is crucial in the preparation of fabric electrodes. These materials mainly include conductive fibers, metal nanowires, carbon-based materials, conductive polymers, and conductive inks. Conductive fibers offer flexibility, metal nanowires provide high conductivity, carbon-based materials combine lightness with strength, conductive polymers are easy to process, and conductive inks are ideal for printing complex patterns. By employing techniques such as knitting, weaving, embroidery, and electrospinning, various high-conductivity fabric electrodes can be designed. Woven fabrics offer high strength and stability, making them suitable for creating structurally demanding conductive fabrics. Knitted fabrics have good elasticity and breathability, making them ideal for flexible and close-fitting conductive fabrics. Embroidered fabrics allow for the design of intricate electrode patterns, while nonwoven fabrics are suitable for producing soft and breathable conductive fabrics.
Additionally, physical and chemical modifications can enhance conductivity, waterproofing, and wear resistance. Methods such as in-situ polymerization, chemical plating, electroplating, surface spraying, and plasma modification can improve the conductivity and stability of fabrics. Moreover, fabric electrodes must meet testing standards for comfort, breathability, durability, waterproofness and sweat resistance to ensure effective transmission of cardiac signals, guaranteeing long-term use, and maintaining good conductivity and structural integrity even after multiple washings and prolonged use.
Research advancements in fabric ECG electrodes include ECG sensor-based electronic textiles, ECG flexible electronic system design, self-powered wearable ECG, and ECG algorithm optimization. ECG sensor-based electronic textiles can integrate various sensors, such as ECG, body temperature, and motion sensors, enabling the simultaneous monitoring of multiple physiological parameters and providing more comprehensive health monitoring data. ECG flexible electronic systems use technologies such as flexible circuits and batteries, making the entire system lighter and more conforming to the body's curves, providing a more comfortable wearing experience. Self-powered wearable ECG systems include energy harvesting, energy management, and real-time ECG monitoring. The ECG algorithm is optimized for the characteristics of wearable devices to improve the accuracy of ECG signal acquisition and data processing efficiency, reduce noise and artifacts, and improve the reliability and accuracy of ECG monitoring. The development of fabric ECG electrodes has not only improved the portability and comfort of ECG monitoring but also brought new possibilities for health monitoring and medical diagnostics.


Preparation and properties of flexible Janus superhydrophobic electrodes#br#

ZHANG Haojie, DING Yaru, LIU Rangtong, WANG Jingjing, YU Yuanyuan

2025, 33(04):  105-112. 

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Textile-based flexible electrodes are widely used in flexible sensing, human-computer interaction, and health detection due to their excellent flexibility, high pore density, and low cost. However, due to the electrically insulating nature of traditional textiles, it is often necessary to use methods such as dipping, spraying, and electrodeposition to make the textile electrically conductive; the conductive materials in these flexible electrodes are prone to detachment during bending and folding. In addition, the electrode material is susceptible to water infiltration in the environment during use, which in turn affects the electrical stability of the material. Therefore, the Janus interface constructed on the surface of the electrode material can achieve waterproof and moisture-permeable performance of the electrode surface.
To construct the Janus interface on the fabric electrode surface to enhance the waterproof and moisture permeability of the electrode, and the stability of the active substance adhesion on the fabric electrode surface, carbon black was electrostatically self-assembled onto the surface of PEI-modified polyester, and then polymerization of polypyrrole on the surface of the carbon coating was used to prepare carbon /polypyrrole/polyester conductive materials; polydimethylsiloxane (PDMS) was used to hydrophobize the conductive fibers and construct the Janus membrane to make the electrode waterproof and self-cleaning. Moreover, PDMS can be used as a curing agent to enhance the adhesion between the conductive material and polyester fibers, preventing the conductive material and the active material from falling off in the state of folding, bending, and twisting. The prepared samples passed a series of tests, and the results showed that: the constructed hydrophobic coating can effectively resist the interference of external liquid droplets, and the static contact angle of water droplets was 151.73°; the Janus structure can effectively increase the infiltration rate of the hydrophilic side, and 8 μL of deionized water was completely absorbed within 1.6 s; due to the solidification of active substances by PDMS, the capacity retention rate of the flexible electrode after 1,000 cycles of bending was 98.4%; the composite coating of carbon black and polypyrrole increased the area-specific capacitance of the flexible electrode to 1,037 mF/cm² (at a current density of 1 mA/cm²); the area specific capacitance retention rate was 96.6% after 4,000 cycles of cyclic charging and discharging. The composite structure design of the superhydrophobic coating and polypyrrole/carbon black exhibits complementary gain effects, providing a material basis for the research of lightweight and high-performance flexible wearable devices and energy storage devices. The constructed Janus electrode with its hydrophobic surface possesses high surface energy, which can accelerate the wetting performance of the hydrophilic surface and enhance the electrochemical reaction rate. 
Through a series of tests and characterizations, it is proved that the prepared unilateral superhydrophobic electrodes have excellent performance in terms of wettability, flexibility, electrochemical performance, and cycling performance, which provides a new idea for the research of lightweight, high-performance, and low-cost flexible electronic energy storage devices.



Effect of different manufacturing processes on ECG signal quality of textile electrodes

ZHOU Jinli, ZHENG Junjie, LIU Siqi, WANG Chenxiao, FAN Mengzhao, YANG Chaoran, LI Yunfei

2025, 33(04):  113-121. 

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Cardiovascular disease (CVD) is a leading cause to mortality in the population, accounting for more than 47% of deaths and posing a serious threat to people's health. Electrocardiography (ECG), as the primary method for detecting the cardiac electrical activity, plays a pivotal role in the prediction and diagnosis of CVD. Conventional ECG systems use disposable Ag/AgCl gel wet electrodes, and while these electrodes are capable of acquiring better bioelectrical signals, the drying up of the gel and the irritation with the skin during long-term use seriously affects patients' willingness to use them. Fabric dry electrodes, by virtue of excellent conformability and comfort, as well as their good electrical conductivity and mechanical stability, have a wide range of applications in wearable ECG monitoring. According to the different preparation processes, fabric electrodes can be mainly categorized into woven fabric electrodes, knitted fabric electrodes and embroidered electrodes.
However, the factors affecting the quality of ECG signals involve not only the preparation process of fabric electrodes, but also the contact impedance between the electrodes and the skin as well as the adaptability under dynamic conditions. To investigate the effects of different preparation processes on the quality of ECG signals from fabric electrodes, we utilized silver/nylon yarn as the primary conductive material and prepared eight different types of fabrics through three distinct processes. These fabrics included three woven fabrics, two knitted fabrics, and three embroidered fabrics. By assessing their surface conductivity, we identified the woven fabric (W3), knitted fabric (K2), and embroidered fabric(E3) types that exhibited the best conductivity. For the woven fabrics, the resistance values increased with the distance between the two test points and were approximately equal when the test points were equidistant. The magnitude of the surface resistance of knitted fabrics was closely related to the coil density. The conductivity of embroidered fabrics was affected by the combination (intersection density) of stitch direction and stitch density, etc. We prepared these three fabrics as cardiofabric electrodes and tested them by electrode-copper-plate low-frequency impedance and electrode-skin contact impedance, and concluded that longer floating-length wires, denser coil structure, higher stitch intersection density, and a larger contact area were important factors for lowering the impedance.
After that, we prepared woven, knitted and embroidered fabric electrocardiographic tapes and comprehensively analyzed the factors affecting the quality of dynamic and static electrocardiographic signals, including structural tightness, contact uniformity and dynamic adaptability. The results showed that different preparation processes and fabric structures significantly affected the conductivity of the electrodes and the quality of contact with the skin, which in turn affected the accuracy and stability of the ECG signals. E3 outperformed both W3 and K2 electrodes in terms of structural compactness, contact uniformity, and dynamic adaptability, and was able to acquire the highest quality ECG signals in both dynamic and static states, with the static Pearson correlation coefficient of 0.94 and the dynamic one above 0.91.


Preparation and properties of PEDOT:PSS/PVA-coated conductive fabrics

WANG Guanghua, HONG Xinghua, ZHU Zijiao, ZENG Xiangsong ZENG Fangmeng

2025, 33(04):  122-130. 

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To expand the application of polyester fabrics in the field of electronic textiles, it is necessary to endow them with conductivity. Therefore, in this study, the conductive coating was prepared by using PEDOT:PSS (Poly (3,4-ethylenedioxythiophene): polystyrene sulfonate), EG (ethylene glycol) and PVA (polyvinyl alcohol), and the conductive coating was evenly coated on the polyester fabric by "coating‒drying" method to prepare the PEDOT:PSS/PVA-coated conductive fabric. Firstly, the optimal range of coating times was determined to be 8, 10, 12 times by single factor experiment to ensure the uniformity of PEDOT:PSS/PVA-coated conductive fabrics. On this basis, the orthogonal experiment of three factors and three levels was designed, and the optimal combination parameters of EG addition amount, PVA solution addition amount and coating times were obtained. The PEDOT:PSS/PVA-coated conductive fabric prepared under the optimal combination parameters showed good electrical conductivity with a resistance of 4.48 Ω and a volume resistivity of 0.09 Ω ·cm. In terms of laundering durability, mechanical properties and biocompatibility, the test results show that the coated conductive fabric has certain laundering durability, and the resistivity after 10 washes is 1.35 Ω ·cm, which is because PVA makes the conductive coating not easy to fall off. The fast and slow elastic recovery retention rates of the coated conductive fabric are 59.77%‒70.34% and 63.26%‒74.43%, respectively. The average breaking strength and elongation at break increase by 59.73 N (6.15%) and 40.4 N (5.78%), respectively, and the improvement of tensile properties is attributed to the synergistic tensile properties of PVA. Additionally, after four hours of contact with the skin, the coated conductive fabric does not cause redness, swelling, or allergic reactions, demonstrating good biocompatibility.
In summary, PEDOT:PSS/PVA-coated conductive fabrics not only perform well in terms of electrical conductivity, but also show excellent properties in terms of laundering durability, mechanical properties and biocompatibility, and have broad application prospects in the field of electronic textiles.


Process optimization and conductivity of flexible silver-clad copper printed circuits

ZHONG Mei, CHEN Xiaodong, QIU Li, DONG Qijing, LONG Tianyu

2025, 33(04):  131-140. 

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With the progress of society and the development of science and technology, people’s demands for health, quality of life, and safety are steadily increasing. Smart clothing, a novel product integrating technology and fashion, has gradually entered people’s lives. It seamlessly combines technology and fashion. By embedding sensors, circuits, microprocessors, and other components, it fulfills functions such as interacting with the wearer, monitoring health status, and enhancing athletic performance. Smart clothing has emerged as a significant trend in the future development of the clothing industry. The design of smart clothing must balance human comfort with complex circuitry arrangements. As the desired functionality increases, the circuitry becomes more intricate, significantly complicating the clothing production process and potentially compromising comfort.
The flexible silver-clad copper printed circuits developed in this study can, to a certain extent, replace traditional wires, effectively simplifying complex circuitry while enhancing clothing comfort without compromising functionality. In this study, samples prepared through single-factor experiments on printed circuits underwent washing and bending tests. Additionally, orthogonal experiments were conducted to determine the optimal printing conditions for the application of these circuits. Through single-factor experiments on thickness, line width, and quality of conductive particles, the approximate range for the orthogonal experiment was determined. After determining the approximate range, the orthogonal experiment was carried out, and three factors were selected, namely thickness, line width, and quality of conductive particles. Each factor had three levels to optimize the process conditions of the flexible printed circuit. Testing and characterization involved the use of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), thickness measurements, resistance tests, bending tests, and washing tests. The resistance of the silver-coated copper printed circuit under different conditions was tested to reflect the conductivity of the printed circuit.
The results of single-factor experiments showed that the optimal conditions were with 4, 5, and 6 layers in thickness, line width of 0.7 cm, 0.8 cm and 0.9 cm, quality of conductive particles of 4.1 g, 4.25 g, and 4.4 g evenly dispersed silver-coated copper particles and 5g of transparent mortar. The uniform dispersion was used as reference to establish a three-factor three-level orthogonal experiment. The results of orthogonal experiment show that the printing circuit has good washability and bending performance under the process of printing 6 layers, namely 0.22 cm, printing line width 0.9 cm, 4.25 g conductive particles and 5 g transparent mortar quality. The sample of silver-coated copper ink printing circuit was prepared. The morphology test, elemental analysis and bending washing temperature test of the sample were carried out. It was found that the printing was uniform and the particle distribution was uniform. The sample exhibited a relatively low resistance of 1.2 Ω, the change before and after washing 10 times was 0 Ω, and the resistance changed by 0.7 Ω after 1000 bending cycles. The sample is not affected by temperature, and it remains relatively stable even at 300°C. The best process summarized provides reference for future flexible printed circuits.