ABSTRACT
Multifunctionality is an important aspect in the field of flexible, wearable, and stretchable electronics. These multifunctional sensors require the integration of electrical conductivity, sensing performance, and heating management. These sensors are based on self-healing materials and self-powered devices. Applications of multifunctional sensors can be found in healthcare, environmental safety and security, indoor air quality monitoring, weather forecasting, soft robotics, and artificial intelligence. Skin-inspired flexible wearable electronic devices have higher potentials in the coming generation of smart, compact, and portable electronic devices. These sensors demand a high degree of sensitivity, accuracy, precision, reproducibility, mechanical flexibility, and low cost. Carbon-based materials such as one-dimensional (1D) and two-dimensional (2D) carbon nanotubes (CNTs) and graphene, silver fractal dendrites, and hydrogel-based materials are mostly used as the active ingredient for the fabrication of flexible sensors. Carbon-based flexible sensors can be used for various applications like humidity sensors, temperature sensors, strain sensors, flexible conductive electrodes, electrochemical sensors, and flexible power devices. A range of mechanisms is observed for these sensors such as piezoelectric, pyroelectric, and piezoresistive. Strain sensors with low voltage driving Joule heating performance and good mechanical stability are used to monitor the bending motion of the six major joints in the human body. This can successfully detect fever and hyperthermia.
