Recent advances and future prospects of flexible sensors based on natural rubber

Sensors have been playing increasingly important roles in the fields of healthcare, environmental monitoring, transportation, and industrial automation. Flexible sensors have been developed to overcome the shortcomings of traditional rigid sensors, especially in the fields of wearable and implantable electronics and soft robotic applications. However, the elastic substrates of current flexible sensors are predominantly derived from petrochemical resources, which face challenges such as non-renewability and suboptimal performance. Natural rubber (NR), as a green and renewable material derived from the latex of Hevea brasiliensis, has been extensively used in tires and various industrial applications due to its excellent elasticity and durability. In recent years, NR has emerged as a promising alternative material for flexible sensors due to its excellent overall properties. The review briefly presents the state of the art in NR-based flexible sensors, including the influence of conductive filler engineering (such as carbon black, metals, and MXenes), sensor design, and fabrication processes on the performance of NR-based sensors. It also discusses the sensing principles of NR-based sensors and their diverse and multifunctional applications (such as electronic skin and human-computer interaction). Finally, the current challenges and future opportunities in the development of NR-based flexible sensors are also outlined.