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). / Doctor of Philosophy / Human-machine interface (HMI) is the technology that enables communication and interaction between humans and machines or computer systems. It plays a vital role in various domains, including consumer electronics, robotics, healthcare, virtual reality, and industrial automation. Fiber-shaped devices have recently emerged as a promising technology for HMI applications due to their flexibility, lightweight nature, and versatile functionality. These devices can be seamlessly integrated into wearable forms, such as clothing or accessories, and even implanted in the body, opening up a wide range of possibilities for HMI. In the past decades, significant progress has been made in developing multifunctional multimaterial fiber devices using the thermal drawing process (TDP). TDP allows for the fabrication of fibers with complex geometries and microstructures by heating and drawing a preform consisting of different materials. However, the current range of materials and structures that can be integrated into these fiber devices is still limited, which hinders their potential applications. This dissertation aims to expand the capabilities of multimaterial fiber devices by exploring new materials and structures that can be incorporated using TDP. The research focuses on three main areas. First, the development and application of stretchable electrical and optical deformation fiber sensors by integrating composite thermoplastic elastomers are explored (Chapter 2). This enables the sensing of various deformations, enhancing the functionality of the fiber devices. Second, the dissertation investigates the creation of multifunctional ferromagnetic fiber robots capable of navigation, sensing, and modulation in minimally invasive surgery (Chapter 3). These robots offer new possibilities for precise and controlled interventions. Lastly, the integration of nano-optoelectrodes and micro robotic chips on the fiber tip using a combination of thermal drawing and lab-on-fiber techniques is explored (Chapter 4). This allows for advanced optical sensing and remote-control capabilities at the fiber tip. Overall, these three aspects of the project broaden the capabilities and functionalities of multifunctional multimaterial fibers, making them highly versatile and suitable for a wide range of applications in wearable technology and biomedicine. These advancements have the potential to revolutionize the field of human-machine interface (HMI) by enabling seamless and intuitive communication, control, and feedback between humans and machines.