Development of Highly Sensitive Humidity Sensor

Sensors currently available for measuring relative humidity (RH) face several limitations that affect their practical applicability. Many exhibit poor responsiveness, limited dynamic range, and high susceptibility to environmental noise, especially under saturated conditions approaching 100% RH. These constraints hinder their effectiveness in critical applications such as biomedical monitoring, environmental sensing, and industrial process control. Here, we propose to leverage Localized Surface Plasmon Resonance (LSPR), an optical phenomenon in metal nanostructures where collective electron oscillations generate sharp resonance peaks. These peaks shift in response to changes in the local refractive index, providing a highly sensitive and label-free method for detecting analytes based on measurable wavelength shifts. The substrate consists of functionalized arrayed gold nanodisks on an invisible substrate (AGNIS), a nanofabricated glass-based platform featuring precisely patterned gold nanodisks. AGNIS offers enhanced sensitivity and enables detection within the visible light spectrum. The performance of AGNIS functionalized by either monolayer graphene or graphene oxide are presented, with initial tests demonstrating measurable shifts in the resonance wavelength upon exposure to saturated humidity conditions. The primary goal of our research is to develop a next-generation humidity sensor that is precise, fast, and responsive, with enhanced sensitivity and stability across a broad humidity spectrum.