Recent Advances in PVA-Based Humidity Sensors: Materials Design and Future Prospects

Abstract

Polyvinyl alcohol (PVA) and its derivatives have gained considerable attention for humidity-sensing applications due to their hydrophilic nature, excellent film-forming ability, and tunable electrical properties. This review systematically examines the last 5 years of research, the fundamental mechanisms of humidity detection using PVA-based materials, and categorizes them into pure PVA, PVA blends with other polymers, and PVA composites containing organic and inorganic materials. For each category, synthesis methods, sensing performance, and humidity sensing mechanisms are analyzed, highlighting how modifications such as polymer blending, incorporation of organic molecules, and addition of inorganic nanostructures like quantum dots, nanofibers, carbon nanotubes, and metal oxide nanoparticles enhance sensitivity, response-recovery behavior, and operational stability. The discussion emphasizes the role of hydrophilic functional groups, conductive pathways, and porous networks in facilitating water adsorption and efficient proton or electron transport. Furthermore, the review identifies current research gaps, including challenges in long-term stability, hysteresis reduction, and scalable fabrication methods. By providing a critical overview of recent advancements and limitations, this work offers insights into designing next-generation PVA-based humidity sensors with improved sensitivity, durability, and practical applicability for environmental monitoring and flexible electronics.