Advances in Humidity Nanosensors and Their Application: Review

As the technology revolution and industrialization have flourished in the last few decades, the development of humidity nanosensors has become more important for the detection and control of humidity in the industry production line, food preservation, chemistry, agriculture and environmental monitoring. The new nanostructured materials and fabrication in nanosensors are linked to better sensor performance, especially for superior humidity sensing, following the intensive research into the design and synthesis of nanomaterials in the last few years. Various nanomaterials, such as ceramics, polymers, semiconductor and sulfide, carbon-based, triboelectrical nanogenerator (TENG), and MXene, have been studied for their potential ability to sense humidity with structures of nanowires, nanotubes, nanopores, and monolayers. These nanosensors have been synthesized via a wide range of processes, including solution synthesis, anodization, physical vapor deposition (PVD), or chemical vapor deposition (CVD). The sensing mechanism, process improvement and nanostructure modulation of different types of materials are mostly inexhaustible, but they are all inseparable from the goals of the effective response, high sensitivity and low response-recovery time of humidity sensors. In this review, we focus on the sensing mechanism of direct and indirect sensing, various fabrication methods, nanomaterial geometry and recent advances in humidity nanosensors. Various types of capacitive, resistive and optical humidity nanosensors are introduced, alongside illustration of the properties and nanostructures of various materials. The similarities and differences of the humidity-sensitive mechanisms of different types of materials are summarized. Applications such as IoT, and the environmental and human-body monitoring of nanosensors are the development trends for futures advancements.

Automated summary

With the advancement of technology revolution and industrialization, the development of humidity nanosensors has become crucial for various applications such as industry production line, food preservation, chemistry, agriculture, and environmental monitoring. Extensive research has been carried out on the design and synthesis of nanomaterials to enhance sensor performance, especially humidity sensing. Different nanomaterials including ceramics, polymers, semiconductors, sulfides, carbon-based materials, triboelectrical nanogenerators, and MXene have been studied for humidity sensing with various nanostructures. This review focuses on the sensing mechanism, fabrication methods, nanomaterial geometry, and recent advances in humidity nanosensors. Capacitive, resistive, and optical humidity nanosensors are discussed, and the similarities and differences in humidity-sensitive mechanisms of different materials are summarized. Future advancements include applications in IoT, environmental monitoring, and human-body monitoring.