With rapid technological developments and lifestyle advancements, electronic sensors are being seamlessly integrated into many devices. This comprehensive handbook explores current, state-of-the-art developments in flexible and wearable sensor technology and its future challenges. Numerous recent efforts have improved the sensing capability and functionality of flexible and wearable sensors. However, there are still many challenges in making them super-smart by incorporating features such as self-power, self-healing, and multifunctionality. These features can be developed with the use of multifunctional nanostructured materials, unique architectural designs, and other advanced technologies. This book provides details about the recent advancements, materials, and technologies used for flexible and wearable sensors. Its wide range of topics addresses the fundamentals of flexible and wearable sensors, their working principles, and their advanced applications. This handbook provides new directions to scientists, researchers, and students to better understand the principles, technologies, and applications of sensors in healthcare, energy, and the environment.