Relative Humidity Optical Sensor Based on Self-Assembled Gold Nanoparticles Covered with Nafion

The detection of humidity plays a vital role in healthcare, industrial, and scientific areas, and the development of an ideal sensor is in continuous progress. In this work, a relative humidity (RH) optical sensor based on localized surface plasmon resonance of self-assembled gold nanoparticles formed by thermal dewetting and coated with Nafion fluoropolymer is under study. Sensor performance has been found to substantially depend on Nafion layer thickness. The best sensing element—an array of gold nanoparticles covered with a 300 nm-thick Nafion—has been shown to possess a linear response in a wide dynamic range of 0–85% RH with a limit of detection down to 0.12%. Thus, a simple and low-cost method for high-accuracy RH detection has been demonstrated.