| Author: | Yang, Mengyan |
| Title: | Design, fabrication, and characterization of flexible and multifunctional TENG and self-powered sensors based on TA-assisted metal electroless deposition |
| Advisors: | Hua, Tao (SFT) Kan, Chi-wai (SFT) |
| Degree: | Ph.D. |
| Year: | 2022 |
| Subject: | Nanogenerators Nanoelectronics Nanotechnology Hong Kong Polytechnic University -- Dissertations |
| Department: | School of Fashion and Textiles |
| Pages: | xxvii, 209 pages : color illustrations |
| Language: | English |
| Abstract: | The development of internet of things and the related sensor technology have been a key driving force for the rapid development of industry and information technology. The requirement of wireless, sustainable and independent operation is becoming increasingly important for sensor networks that currently could include thousands even to millions of sensor nodes with different functionalities. For these purposes, developing technologies of self-powered sensors that can utilize the ambient environmental energy to drive the operation themselves is highly desirable and mandatory. The realization of self-powered sensors generally has two approaches: the first approach is to develop environmental energy harvesting devices for driving the traditional sensors; the other is to develop a new category of sensors - self-powered active sensors - that can actively generate electrical signal itself as a response to a stimulation/triggering from the ambient environment. The recent invention and intensive development of triboelectric nanogenerators (TENGs) as a new technology for mechanical energy harvesting can be utilized as self-powered active mechanical sensors, because the parameters (magnitude, frequency, number of periods, etc.) of the generated electrical signal are directly determined by input mechanical behaviors. Triboelectric nanogenerators (TENGs) are widely used in self-powered electronic devices and tactile sensors. However, fabricating high-performance TENGs and self-powered sensors remains challenging. There is still a lot of room for optimization in the selection of friction materials, the structural design and optimization of TENG, and the optimal design of dielectric materials. To address these issues, this thesis focuses on the design and development of flexible and wearable TENG-based self-powered sensors. In particular, the ability of metals with different properties prepared by TA (tannic acid)-assisted metal electroless deposition to serve as electrodes of TENG was investigated to improve the output performance of TENG by adjusting the dielectric properties of friction materials was explored. Firstly, for the first time, we use the facile, low-cost, and universal electroless deposition (ELD) technology to fabricate non-conductive black Cu to enhance the electrical output performance and sensitivities of TENG based tactile sensor. The output performance and sensitivities of the equipment are significantly improved by the introduction of black Cu nanoparticles (NPs) coated cellulose filter paper (CFP) into the PDMS matrix. With an optimal load of black Cu NPs, the composite film-based TENG produces the highest surface charge density exhibited by high sensitivities of 1.56 V N-1, 3.5 times of that obtained via PDMS-based TENG under the same conditions. These properties facilitate the developed device to be competent at monitoring a kind of human movements, such as finger touching and bending. The proposed strategy not only demonstrates a promising potential of developing large-scale practical self-charging equipment and improving the output performance and sensitivities of TENG based tactile sensors but also provides a new perspective for applications in other fields. Through continuous research on the TENG-based self-powered active sensors in the coming years to further improve the sensitivity and realize the self-powered operation for the entire sensor node systems, they will soon have broad applications in touch screens, electronic skins, healthcare, environmental/infrastructure monitoring, national security, and more. Secondly, global warming and other world climate issues have spawned extensive research on the green, recyclable and biodegradable distributed energy harvesting triboelectric nanogenerator (TENG) for the collection of renewable energy. Cellulose filter paper (CFP), as a biocompatible natural material with a unique three-dimensional porous network structure, high crystallinity and excellent mechanical flexibility, can be used to create biodegradable and environmentally friendly TENGs. Here, we have developed a green and recyclable CFP-based energy harvesting and human-computer interaction system based on the single-electrode structure. It is composed of PVDF-coated CFP and conductive Cu-coated CFP as friction layer and electrode respectively. The degradation experiment verified the composite film materials can be completely dispersed and dissolved in deionized (DI) water in 30 min using an ultrasonic instrument, which fully proves the green and environmental protection of the prepared CFP-based TENG. We also thoroughly studied the output properties of the fabricated CFP-based TENGs, which demonstrates a maximum output voltage of 192 V, output current of 9.3µA, and output power at 736.7 mW m-2. The CFP-based TENGs can be conveniently adopted to power commercial electronic products and as a wearable interface to control computer programs. This research demonstrates the effective way to develop CFP-based TENG for energy collecting and human-computer interaction devices with high biodegradability, which is important for realizing the environmental protection of electronic equipment, promoting energy conservation and emission reduction, and achieving carbon neutrality. In summary, conductive Cu films were fabricated as electrodes for TENGs, and non-conductive black Cu NPs were used to tune the dielectric properties of friction materials, providing an idea for extending the application of TA-assisted metal electroless deposition (ELD) methods. Meanwhile, due to the wide application of ferrous metals in catalysis, photothermal conversion, and other fields, this novel extension of ELD technology can not only improve the output performance of TENGs, but also provide a new perspective for stimulating excellent applications in this field, including wearable devices, artificial skin, catalysis, photothermal conversion, biomedicine and other industries. |
| Rights: | All rights reserved |
| Access: | open access |
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