LEE- Tekstil Mühendisliği Lisansüstü Programı

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http://hdl.handle.net/11527/19465

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Yazar "Kalaoğlu, Fatma" ile LEE- Tekstil Mühendisliği Lisansüstü Programı'a göz atma
  • Öge
    Development of stretchable conductive fabric through different metals coating approach for e-textile applications
    (Graduate School, 2022-07-25) Hassan, Zuhaib ; Kalaoğlu, Fatma ; 503122807 ; Textile Engineering
    This study aims to manufacture and characterize various types of conductive (cotton knitted and polyester knitted) fabrics. The fabrics were prepared through the electro-less copper metal coating approach. The effect of copper electroleess plating on different types of fabric structures and on different crossections of yarns was also observed. The main response of prepared fabric was electrical conductivity, EMI shielding and their durability against washing and rubbing. The current research activity has multiple benefits considering extensive comparison with other studies. Previously electroless plating has been performed by different salts and reducing agents' combinations over different fibres. However, there were no study available to metallize the fabric structures having different GSM and different cross section of fibres. Secondly, we have also studied the effect of different fibrous cross-section (round, hollow round, W shape and octolobel) against copper electroless plating. At first, nine-combed cotton knitted fabric samples with different yarn fineness and elastane percentage were selected in order to see effect of these parameters on electrical conductivity and physical properties of samples such as an increase in weight and thickness, impact of washing cycles and abrasion resistance on the electrical conductivity of the fabric sample. The surface morphology of all the knitted cotton fabric samples were also explored before and after the coating method via scanning electron microscope (SEM) and it showed a remarkably uniform deposition of copper on the fabric surface. the energy dispersive spectroscopy (SEM-EDX) was performed to determine the coated material content on the surface of the fabric after the metal coating process. The utility of conductive fabrics was analyzed for electromagnetic shielding ability over frequency range of 30 MHz to 1.5 GHz. The electrical conductivity and amount of metal deposition was found to be higher for the fabric samples having less GSM and higher cotton percentages in their structures. The results revealed that knitted cotton fabric of 5% elastane with the finer yarn count (Ne=40/1) showed lowest resistivity (3.24 Ω.cm) as compared to the other knitted cotton fabric of 10% elastane with a finer count (Ne=40/1) or 5% elastane with coarser (Ne=30/1). The increase in elastane content into fabric structure also influences the fabric stretchability. The objectives of second part of the study were, to carry out research with the best performing three samples obtained from the first part of the study and three single jersey knitted cotton fabric samples were selected. The selected fabric samples with GSM (136, 154 and 176 GSM) out of nine fabric samples were used in this part. These fabric samples provided the lowest value of electrical resistivity coupled with high EMI shielding and more contents of metal particles. Thereafter, the selected samples were pre-treated with laser to enhance the surface roughness, then electroless plating was performed in order to see the impact of roughness on copper deposition. This section of the research work addresses the development and characterization of conductive cotton fabrics treated with lasers in context of copper (Cu) metallization methodologies. The abrasion resistance, thickness, and durability of the laser-treated knitted cotton fabric samples were investigated. Additionally, samples exhibited exceptionally consistent deposition of Cu nanoparticles on the surface of cotton fabric when the surface morphology of the laser-treated surfaces was examined by employing the scanning electron microscope (SEM) both before and after the coating procedure. To assess the elemental analysis on the surface of the treated samples following the electroless metallization process, an energy dispersing spectroscopy (SEM-EDX) examination was performed. This section of the study indicated that fabric samples that had been laser-treated outperformed untreated fabric samples in terms of wear resistance. Abrasion resistance being one of the significant features in electric textile applications, laser-treated samples might thereby be the best options. The third part of the study was the development and characterization of conductive textured and non-textured polyester fabrics with different cross-sections. The electroless copper plating method was selected to impart conductivity on fabric structures. The deposition of copper nanoparticles on textured and non-textured polyester fabrics was characterized by electrical conductivity, electron scanning microscopy (SEM), microscopic morphology, and energy dispersive X-ray spectroscopy (EDX). SEM images revealed a uniform copper nanoparticle coating of a thin film on textured and non-textured polyester fabrics. The properties of conductive textured polyester fabrics were compared in terms of electrical conductivity, wear resistance, thickness and durability with non-textured conductive polyester fabrics. Structural studies showed that the crystalline surface of the textured and non-textured polyester fabric structure is not affected by electroless metallization. Conductivity studies have shown that textured (lowest resistivity 2.18 Ω.cm) and non-textured (lowest resistivity 76.39 Ω.cm) polyester fabrics have good electrical conductivity. When the durability of conductive textured and non-textured polyester fabrics was examined against washing and rubbing fastness, the textured polyester fabrics showed good retention of copper nanoparticles by maintaining their electrical conductivity level after 250 abrasion cycles. Furthermore, resistivity analysis was also carried to study the effect of copper metallization and conductivity against different morphological structures of fibres. It was observed that there are lower values of electrical resistivity for each coated sample. The resistivity was found to be lowest for hollow round coated fibres (either textured or non-textured). The behaviour of metal deposition for hollow round fibers and electrical conductivity was further justified from the SEM analysis. The W shape fibers showed less amount of metal deposition and higher electrical resistivity values as compared to all. The final applications of developed copper plated fabrics are in the field of smart textiles, sensors, stretchable actuators, EMI shielded panels and stretchable electrodes. Keywords: Conductive textiles, Electroless plating, Copper coating, Electromagnetic interference shielding, sensors and actuators, Stretchable conductive fabrics, Smart textiles, metal coatings, textured polyester fabrics, Metal coated, Cross-sectional fiber.
  • Öge
    Textile-based soft robotics for active assistance and rehabilitation
    (Graduate School, 2024-07-10) Yılmaz, Ayşe Feyza ; Atalay, Özgür ; Kalaoğlu, Fatma ; 503192801 ; Textile Engineering
    Recent advancements in the field of robotics have proven that soft robots can be used as wearable supports for neuromuscular disorders due to their compliance and ability to imitate complex motions. Soft pouch motors, engineered to mimic the natural movements of skeletal muscles, play a crucial role in advancing robotics and exoskeleton development. However, fabrication techniques often involve multi-stage processes; they lack soft sensing capabilities and are sensitive to cutting and damage. Previous research showed that elastomeric, i.e. silicone, soft pneumatic actuators have a great potential to create soft-wearable robotic devices for these applications. Nevertheless, it takes time to manufacture these types of actuators due to long preparation times. Although silicone-based materials have favorable properties, such as heat, chemical resistance, and the capacity to conform to different range motions, they do present challenges in terms of material density, stiffness, and strength. This work introduces a new textile-based pouch motors with the capacity for biaxial actuation and capacitive sensory functions, achieved through the application of computerized knitting technology using ultra-high molecular weight polyethylene yarn (Spectra®) and conductive silver yarns. This method enables the rapid and scalable mass fabrication of robust pouch motors. The resulting pouch motors exhibit maximum lifting capacity of 10 kilograms, maximum contraction of 53.3% along the y-axis, and transverse extension of 41.18% along the x-axis at 50 kPa pressure. Finite Element Analysis (FEA) closely matches the experimental data, validating the design and performance of these pouch motors. The capacitance signals in relation to contraction motion are well-suited for detecting air pressure levels and hold promise for applications requiring robotic control. A practical demonstration of the potential of these pouch motors is showcased through the development of a soft ankle exosuit designed to provide lifting support for individuals with foot drop, a condition that impairs the ability to lift the front part of the foot. The exosuit effectively elevates an ankle joint simulator to a 20-degree angle. Moreover, the application of approximately 35 degrees of dorsiflexion torque to a human foot has been successfully achieved under a pressure of 50 kPa, highlighting its potential in assisting with mobility challenges. This study underscores the importance of incorporating both actuation and sensing capabilities in soft robotic systems, which can significantly enhance functionality and user experience. This work not only advances the field of soft robotics but also offers a solution for improving the quality of life for individuals with impaired muscle function. Through the integration of robust, scalable fabrication techniques and advanced materials, this research paves the way for the next generation of assistive devices, promising greater independence and mobility for users. The most challenging aspect of this work was to provide dorsiflexion movement to the foot through a textile-based actuator. Therefore, numerous preliminary studies and methods were attempted to achieve this goal. These preliminary studies evaluated actuators that generated insufficient force for lifting the foot and were applied in exoskeleton-assisted glove applications for the hand. These studies were included in the "Previous Works" section of the thesis. Moreover, healthy individuals naturally perform the gait phases of "heel strike," "stance," "heel off," and "swing" during walking. When the swing phase begins, the ankle dorsiflexes, lifting the toes off the ground to ensure the continuity of the walking cycle, which starts with the heel strike. During the preliminary studies, a novel interdigital capacitive textile sensor was developed using knitting technology to analyze gait through human knee movements. The details of this study are included in the "Previous Works" section. However, controlling the robotic system using this sensor proved to be complex. Therefore, a simpler method was implemented: a textile-based presence/absence sensor placed on the heel. This approach simplified the control system, making it more manageable.