Master of Science By Research

Permanent URI for this collectionhttp://192.248.9.226/handle/123/15839

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    Development of wearable triboelectric Nanogenerators using optimised knitted structures
    (2023) Dassanayaka HDDG; Wanasekara ND; Dharmasena IG
    The rapid development of portable and wearable electronic devices has increased the demand for sustainable, low-maintenance, and lightweight power-supplying methods. One of the leading technologies in fabricating such power-supplying methods is triboelectric nanogenerators, which can be used to generate electricity using human motion. Triboelectric nanogenerator works on contact electrification and electrostatic induction, and a plethora of fabrication techniques have been used in the fabrication of triboelectric nanogenerators. One such technique is knitting technology, which is one of the major textile fabrication methods. In this research, the effect of different knitting parameters and knitted structures on electrical performance of triboelectric nanogenerators were evaluated. The knitting parameters considered are stitch length and yarn count, and knitted structures considered are single jersey, rib, and interlock. Based on the results obtained, a wearable knitted sensor was fabricated using nylon 66 and silver as triboelectric surfaces. This sensor was able to identify finger bendings and tappings. Moreover, the durability of the electrical outputs of the knitted sensor was evaluated by studying the behavior of the conductive fabric’s resistance when subjected to washing and abrading. The wearable performance of the triboelectric sensor was studied by measuring the air permeability and abrasion resistance of different sections of the sensor. Finally, the capability of using the sensing fabric for IoT applications was explained.
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    item: Thesis-Abstract
    Towards an understanding of Sri Lankan consumer’s second-hand fashion consumption
    (2022) Geegamage PHTA; Ranaweera HRA; Halwatura RU
    One of the worst pollutants in the world is allegedly the fashion industry. Landfills receive enormous amounts of post-consumer trash each year. However, as current customers' awareness of environmental issues grows, they are increasingly drawn to wearing used clothing. The concept of second-hand fashion consumption, however, clearly lacks awareness in the Sri Lankan context. In the qualitative study, it incorporates the theoretical notion of the means-end chain model and demonstrates five consideration values of second-hand consumers: price-consciousness, emotional bond consciousness, comfortability consciousness, quality and brand consciousness, and social and environmental consciousness. Additionally, we demonstrate non-second-hand fashion consumers' consideration values of social status consciousness, hygienic consciousness, comfortability consciousness, quality and brand consciousness, and self-expressive consciousness. Ten hypotheses were developed based on the findings. Hypotheses were investigated using a survey questionnaire in study two. The data were analysed using multiple regression analysis in SPSS. As the findings indicated, consumer purchase intention and word-ofmouth intention grew as emotional bonds and consumer knowledge increased, and with low and medium consumer knowledge, they decreased. So, consumers with high emotional bonds have the highest consumer knowledge, purchase intention, and word-of-mouth intention. Purchase intention increased as hygienic factors and consumer knowledge grew, whereas it declined at low and medium levels, indicating that consumers with high knowledge had the highest purchase intention. This study sheds some light on the growing knowledge of second-hand consumption by first identifying Sri Lankan consumer values and then studying how consumer knowledge interacts with their purchase intention and also word-of-mouth intention. This study also has practical implications by highlighting a few opportunities and constraints related to the second-hand fashion retail sector in Sri Lankan fashion retail.
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    item: Thesis-Abstract
    Development of a triboelectric nanogenerator using nylon-hybrid yarn
    (2021) Gunawardhana KRSD; Wanasakara ND
    Human needs are continually changing with the enhancement of novel electronic technologies. The Internet of Things (IoT), Artificial Intelligence, and 5G technology have led to state-ofthe-art products to improve the living standards if a rapidly increasing global population. Wearable electronics, which closely associated with human activities, are typically powered with replaceable or rechargeable batteries. There are significant drawbacks of existing power supplies for wearable electronics, including low flexibility and stretchability, limited autonomy, low biocompatibility and high weight. Portable and renewable energy harvesting are possible from a wearer's physical movements in an ambient environment. In recent years, this has been achieved using Piezoelectric and Triboelectric nanogenerators, which act as an alternative to batteries for powering wearable electronic devices. However, such technologies' challenges include the magnitude and consistency of power output, fabrication for mass-scale production and operation under small mechanical movements. This project focus on developing a triboelectric nanogenerator using silver-coated nylon yarn, silicone and polyurethane with a rib knitting structure. The basic fundamental methods of applying triboelectric layers such as dip coating, printing and yarn coating methods analysis for wearable and electrical outputs. Yarn coated sample shows the best results with even coverage, good air permeability (101 cm3/cm2/s), high moisture management properties and high stretchability (Stretchability -75.82%, Recoverability- 76.67% and elastic modulus of 1.4093). Furthermore, when polyurethane bonded air textured sample used as a secondary triboelectric layer, the final device shows a maximum short circuit current of 3.412 µA/m , the charge density of 6.12 µC/m2 and maximum open-circuit voltage of 51.08 V under the 1 mm amplitude over 1 Hz frequency. Finally, the device used to generate a peak power of 116.8 µW/m2 through 10 GΩ resistors under the same motion profile.
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    item: Thesis-Full-text
    Development of conductive and biodegradable nanofibrous yarns : study of electrical and mechanical properties
    (2020) Weerasinghe PVT; Wanasekara N D; Dissanayake DGK
    Electrically conductive and biodegradable materials are desired for a vast array of applications in wearable and flexible electronic areas to address the growing ecological problem of e-waste. Herein, we report on the design and fabrication of all-organic, conductive and biodegradable yarn using polyaniline (PANi) and polycaprolactone (PCL). The process of PANi incorporation is achieved in two ways; i) electrospinning a blend of PANi and PCL solution ii) in-situ polymerization of PANi on the nanofibrous surface of PCL electrospun fibers. The electrospun PANi incorporated webs are cut into ribbons and twisted to develop twisted yarns. A customized setup was used to produce continuous electrospun yarns. The effect of different degrees of PANi blended into PCL was investigated. Moreover, the effect of an array of aniline concentrations in coated fibers were studied. PCL/PANi blended solution with 2% PANi resulted in nanofibers with resistance of 10 ± 4 MΩ/cm. Fibers coated with 1% aniline concentration resulted in the core-shell fibers with of 50 ± 8 kΩ/cm. Increasing the number of plies of yarn to 3 plies resulted in a 3-fold reduction of the resistance. The twisted plied yarns were incorporated into fabric by stitching or weaving to demonstrate the stability of conductivity over mechanical forces. Both PANi blended and PANi coated yarns were found to be biodegradable in controlled environmental conditions. The use of PANi blended yarn as a biomaterial for tissue engineering and PANi coated yarns as a wearable electrode for capacitive sensors were demonstrated. The electromechanical behavior of PANi coated yarn is expected to provide inspiration for the production of highly sensitive strain sensors. This approach presents an early step on the way to the realization of all organic conductive biodegradable nanofibrous yarns for sustainable smart textiles.
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    item: Thesis-Full-text
    Evaluation of the satisfaction in terms of product quality of women's casual wear in Sri Lanka
    (2019) Appuhamy KHAGE; Matharaarachchi R
    There has been a significant growth in the apparel retailer market in Sri Lanka during the last decade. Statistic shows middle-class population had grown faster in Sri lanka, and branded and organized retail has improved with changing spending patterns of people. A tremendous retail potential can be identified in city Gampaha, as the second largest household income sector of the country. It had been expected to witness retail development in terms of apparel retailing. The sustainability of this segment of apparel retail depended, on the ability to satisfy target customers satisfaction. The purpose of this study is to evaluate the level of customer satisfaction based on quality of clothing that they were offered by the retailers. Hence the study provides directions to fashion retailers and product developers to understand the key measures of product quality that affect level of customer satisfaction. Further the study helps to understand the level of customer satisfaction. A survey of 143 customers, who are frequently visiting casual wear retailer shops, were targeted and questioned using the questionnaire form, to get the required details for the research. This data was analyzed by using questionnaire surveys to measure the level of customer satisfaction towards product quality. Researcher has disregarded the customers who do not represent the population & as a result the designated customer group had come down to 100 customers for the data analyzing. The results of the research emphasized that, customers are satisfied with Performance, Features, Reliability, Conformance, Durability, Serviceability & Perceived quality. But they are negatively satisfied with Aesthetics, Features, & Durability. This research finding, and recommendations are verified & tested in the research paper by using the analytical tables and figures. Finally, this thesis presents the quality gap of the product offering as a means of listening to the real voice of customer and improve customer satisfaction. Further, this research is an instrument developed, to provide an insight, to which appeal retailers can directly understand, the levels of full-filled expectations of their clientele, with the offering they provided, based on apparel product quality.