High-Sensitivity Cellulose-Based Fiber-Optic SPR Humidity Sensor With Temperature Compensation

Achieving both high sensitivity and effective temperature compensation is crucial for high-performance humidity sensors. However, integrating temperature compensation often compromises sensitivity. We develop a fiber-optic surface plasmon resonance (SPR) sensor that integrates a cellulose-based humidity-sensing module and a polydimethylsiloxane (PDMS)-based temperature-sensing module on a plastic-coated multimode optical fiber. By utilizing a highly humidity-sensitive cellulose film, we developed a sensor that delivers high sensitivity while incorporating temperature compensation. The sensor exhibits an average humidity sensitivity of -9.15 nm/RH% and a maximum sensitivity of -14.1 nm/RH% within a relative humidity (RH) range of 25%-70%. In addition, it shows a temperature sensitivity of -2.48 nm/°C between 25 °C and 45 °C. By employing a sensitivity coefficient matrix, the system achieves real-time temperature compensation, thereby significantly enhancing humidity measurement accuracy. Due to its high sensitivity, robust performance, and simple structure, the proposed sensor demonstrates strong potential for practical applications, such as human respiration monitoring and health status analysis.