Laser-processed polymers for humidity sensors and the application

Humidity sensors are widely used in fields such as environmental monitoring, healthcare, agriculture, and industry. Their performance improvement relies on innovations in materials and preparation technologies. Traditional humidity sensors have problems such as slow response, mechanical brittleness, and limited sensitivity, while polymer materials have become ideal alternatives due to their flexibility and processability. In recent years, laser processing technology has brought revolutionary progress to polymer humidity sensors through high-precision, mask-free, green and efficient micro-nano structure preparation methods. This review systematically elaborates on the material systems, preparation processes, sensing mechanisms, and performance optimization strategies of laser-processed polymer humidity sensors, with a focus on analyzing the enhancing effects of laser-induced porous structures, functional modification, and process parameter regulation on the sensitivity, response speed, and stability of the sensors. In addition, the review discusses the practical applications of such sensors in fields such as wearable health monitoring, smart agriculture, and food quality monitoring, and looks forward to future research directions such as self-powered, multi-modal integration, and degradable materials. By comprehensively sorting out the intrinsic connections between “materials − processes − performance − applications”, this review aims to provide theoretical references and application guidance for the design and industrialization of high-performance, flexible, green and sustainable humidity sensors.