Browsing by Author "Zhang, Yujing"

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    Multifunctional Multimaterial Fibers for Sensing and Modulation in Wearable and Biomedical Applications
    Zhang, Yujing (Virginia Tech, 2023-08-03)
    The aim of this dissertation is to summarize my research on the development of multifunctional multimaterial fibers that are designed and produced for sensing and modulation applications in wearable and biomedical fields. Fiber-shaped devices have gained significant attention due to their potential in human-machine interface applications. These devices can be woven into fabrics to create smart textiles or used as implantable probes for various biomedical purposes. To meet the requirements of human-machine interface, these fiber devices need to be flexible, robust, scalable, and capable of integrating complex structures and multiple functionalities. The thermal drawing technique has emerged as a promising method for fabricating such fiber devices. It allows for the integration of multiple materials and intricate microstructures, thereby expanding the functionality and applications of the devices. However, the range of materials and structures that can be integrated into these fiber devices is still limited, posing a constraint on their potential applications. To address this limitation, the dissertation focuses on expanding the range of materials and structures that can be integrated into multimaterial fiber devices. This involves the development and application of stretchable electrical and optical deformation fiber sensors by incorporating composite thermoplastic elastomers through the thermal drawing process (Chapter 2). Additionally, the dissertation explores the use of the thermal drawing technique to create multifunctional ferromagnetic fiber robots capable of navigation, sensing, and modulation in minimally invasive surgery (Chapter 3). Furthermore, the integration of nano-optoelectrodes and micro robotic chips on the fiber tip using the combination of thermal drawing and lab-on-fiber techniques is investigated (Chapter 4). The dissertation concludes with an overview of the research findings and potential future directions in the field of multifunctional multimaterial fiber devices (Chapter 5).
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    Scalable Fabrication of Highly Flexible Porous Polymer-Based Capacitive Humidity Sensor Using Convergence Fiber Drawing
    Tousi, Maryam Mesgarpour; Zhang, Yujing; Wan, Shaowei; Yu, Li; Hou, Chong; Yan, Ning; Fink, Yoel; Wang, Anbo; Jia, Xiaoting (MDPI, 2019-12-02)
    In this study, we fabricated a highly flexible fiber-based capacitive humidity sensor using a scalable convergence fiber drawing approach. The sensor’s sensing layer is made of porous polyetherimide (PEI) with its porosity produced in situ during fiber drawing, whereas its electrodes are made of copper wires. The porosity induces capillary condensation starting at a low relative humidity (RH) level (here, 70%), resulting in a significant increase in the response of the sensor at RH levels ranging from 70% to 80%. The proposed humidity sensor shows a good sensitivity of 0.39 pF/% RH in the range of 70%–80% RH, a maximum hysteresis of 9.08% RH at 70% RH, a small temperature dependence, and a good stability over a 48 h period. This work demonstrates the first fiber-based humidity sensor fabricated using convergence fiber drawing.
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    Spatially expandable fiber-based probes as a multifunctional deep brain interface
    Jiang, Shan; Patel, Dipan C.; Kim, Jongwoon; Yang, Shuo; Mills, William A. II; Zhang, Yujing; Wang, Kaiwen; Feng, Ziang; Vijayan, Sujith; Cai, Wenjun; Wang, Anbo; Guo, Yuanyuan; Kimbrough, Ian F.; Sontheimer, Harald; Jia, Xiaoting (Nature Research, 2020)
    Understanding the cytoarchitecture and wiring of the brain requires improved methods to record and stimulate large groups of neurons with cellular specificity. This requires miniaturized neural interfaces that integrate into brain tissue without altering its properties. Existing neural interface technologies have been shown to provide high-resolution electrophysiological recording with high signal-to-noise ratio. However, with single implantation, the physical properties of these devices limit their access to one, small brain region. To overcome this limitation, we developed a platform that provides three-dimensional coverage of brain tissue through multisite multifunctional fiber-based neural probes guided in a helical scaffold. Chronic recordings from the spatially expandable fiber probes demonstrate the ability of these fiber probes capturing brain activities with a single-unit resolution for long observation times. Furthermore, using Thy1-ChR2-YFP mice we demonstrate the application of our probes in simultaneous recording and optical/chemical modulation of brain activities across distant regions. Similarly, varying electrographic brain activities from different brain regions were detected by our customizable probes in a mouse model of epilepsy, suggesting the potential of using these probes for the investigation of brain disorders such as epilepsy. Ultimately, this technique enables three-dimensional manipulation and mapping of brain activities across distant regions in the deep brain with minimal tissue damage, which can bring new insights for deciphering complex brain functions and dynamics in the near future.