abstract: The field of flexible displays and electronics gained a big momentum within the recent years due to their ruggedness, thinness, and flexibility as well as low cost large area manufacturability. Amorphous silicon has been the dominant material used in the thin film transistor industry which could only utilize it as N type thin film transistors (TFT). Amorphous silicon is an unstable material for low temperature manufacturing process and having only one kind of transistor means high power consumption for circuit operations. This thesis covers the three major researches done on flexible TFTs and flexible electronic circuits. First the characterization of both amorphous silicon TFTs and newly emerging mixed oxide TFTs were performed and the stability of these two materials is compared. During the research, both TFTs were stress tested under various biasing conditions and the threshold voltage was extracted to observe the shift in the threshold which shows the degradation of the material. Secondly, the design of the first flexible CMOS TFTs and CMOS gates were covered. The circuits were built using both inorganic and organic components (for nMOS and pMOS transistors respectively) and functionality tests were performed on basic gates like inverter, NAND and NOR gates and the working results are documented. Thirdly, a novel large area sensor structure is demonstrated under the Electronic Textile project section. This project is based on the concept that all the flexible electronics are flexible in only one direction and can not be used for conforming irregular shaped objects or create an electronic cloth for various applications like display or sensing. A laser detector sensor array is designed for proof of concept and is laid in strips that can be cut after manufacturing and weaved to each other to create a real flexible electronic textile. The circuit designed uses a unique architecture that pushes the data in a single line and reads the data from the same line and compares the signal to the original state to determine a sensor excitation. This architecture enables 2 dimensional addressing through an external controller while eliminating the need for 2 dimensional active matrix style electrical connections between the fibers. / Dissertation/Thesis / Ph.D. Electrical Engineering 2012

<p>Textiles have gained popularity in wearable products due to their potential for wearability, comfort, flexibility, breathability, and seamless fit to the human body. The growing demand for remote telehealth monitoring has led to advancements in the field of e-textiles. Various approaches, such as dip coating, screen printing, inkjet printing, and vapor deposition, are utilized to overcoat fabrics with active nanomaterials. However, practical deployment still faces challenges due to a lack of rapid prototyping for scalable and customizable e-textiles. To meet the requirements of large-scale batch production, high-resolution electrode line width, and long-term durability, new platform technologies have been established to convert existing textiles into multifunctional e-textiles. These studies have also revealed the process-structure-property relationships of various e-textiles.</p> <p>Chapter I overviews the recent results and current limitations of e-textiles in wearable sensing and display. Since people stay and work in various circumstances, continuous monitoring of physical, electrophysiological signals on skin in ambulatory manners is necessary to evaluate hazardous situation or chronicle symptoms. For these reasons, fabrication of smart e-textiles is crucial. In this chapter, various conductive materials, overcoating methods, and sensor structures for physical and electrophysiological sensors are reviewed. In addition, as a useful user communication tool with different sensor system, e-textile formats of displays are developed. The comprehensive e-textile displays from DC-driven to AC-driven are presented.</p> <p>Chapter II introduces a dual-regime spray technique that enables the direct writing of functional nanoparticles onto commercial 4-way stretchable textiles up to a meter scale with high-resolution mask-free patterning. The resulting e-textiles maintain the intrinsic properties of the fabric and can conform to various body shapes, enabling high-fidelity recording of physiological and electrophysiological signals under ambulatory conditions. Field tests have shown the potential of these e-textiles for minimally obtrusive remote telehealth monitoring of large animals.</p> <p>Chapter III presents an in-situ polymerization and patterning technique that utilizes the dual-regime spray method to synthesize conductive polymers directly onto commercial stretch textiles. The resulting e-textiles are utilized for strain sensors that conform closely to the human body, providing exceptional measurement accuracy and fidelity in capturing physical signals and motion detections.</p> <p>Conclusion section summarizes this dissertation with pointing out important results and discussions of each study. As an innovative additive manufacturing technology, dual-regime spray system, was established and developed to open new field in manufacture of e-textile. At last of this section, the potential research opportunities and perspectives are addressed. </p>