Dual side-coupled plasmonic nanosensor for simultaneous detection of temperature and humidity

Abstract

A dual-cavity coupled plasmonic sensor based on metal-insulator-metal structure is proposed to realize the simultaneous detection of humidity and temperature. The transmission spectra and magnetic field distributions of structure are numerically investigated by finite element method. The double Fano resonance is tuned independently by changing the refractive index (1.01–1.09) of mediums in two resonators separately. The sensor achieves a maximum sensitivity of 2215 nm/RIU, with a quality factor (Q) of 70.71 and figure of merit (FOM) of 71.29 RIU⁻¹. The simultaneous detection of humidity and temperature can be realized by adding polyvinyl alcohol (PVA) and polydimethylsiloxane (PDMS) into two cavities as humidity-sensitive and temperature-sensitive materials, respectively. The humidity sensitivity and temperature sensitivity are −0.24 nm/%RH and −1.015 nm/°C, respectively.