SPR-MOF terahertz sensor for simultaneous high-sensitivity temperature and humidity sensing

Abstract A terahertz (THz) surface plasmon resonance (SPR)-based microstructured optical fiber (MOF) sensor is proposed for the precise dual-parameter monitoring of temperature and humidity. Molybdenum disulfide (MoS 2 ) is deposited as the SPR excitation layer on both the internal and external channels of the sensor. Meanwhile, polydimethylsiloxane (PDMS) and polyvinyl alcohol (PVA) are filled into two separate channels, serving as the sensing media for temperature and humidity, respectively. The modal characteristics and structural parameters of the sensor are systematically analyzed and optimized using numerical simulations based on the finite element method (FEM). Simulation results demonstrate that within the range of 20–90 °C, the temperature-sensing channel exhibits a maximum temperature sensitivity of 0.1 μm/°C, a maximum figure of merit (FOM) of 113.83 RIU −1 and a resolution of 4.5 × 10 −8 RIU. In the humidity range of 40%–80% relative humidity (RH), the humidity-sensing channel achieves an ultra-high humidity sensitivity of 3.275 μm/%RH, along with a FOM of 89.95 RIU −1 , and a resolution of 4.19 × 10 −9 RIU. Furthermore, it is verified that there is no crosstalk between the resonance peaks responsive to temperature and humidity. Owing to its excellent sensitivity and unique features, the SPR-MOF sensor holds promising applications prospects in multifunctional sensing scenarios.