Terahertz Spoof Plasmonic Sensor with Resonance Sensing Capability for Wood Moisture Detection

Exact detection of moisture content is essential to preserve the quality of wood, since it can stop swelling and shrinkage. This paper proposes a theory based on the interaction between spoof surface plasmon polaritons (SSPPs) and spoof localized surface plasmon (SLSPs) for the purpose of detecting moisture content in wood utilizing a planar terahertz sensor structure. The numerous resonance frequencies generated by this sensor are used to detect moisture content by measuring variations in the shift of these resonance frequencies within a designated operating band. When the standard block is fixed, the simulated results show that the sensor has a fix resonance frequency. Conversely, if the moisture in the wood being tested is higher than that of the standard block, resonance frequencies move towards lower frequencies, suggesting that the proposed method works well for screening wood that does not match moisture content standards. The topic of wood processing can benefit from the practical applications of this research. Furthermore, these results provide a path toward the development of planar spoof plasmonic devices into useful sensors in the terahertz regime.