Terahertz All-Metal Metamaterial Humidity Sensor Based on Silk Fibroin

Terahertz (THz) waves are highly sensitive to humidity changes due to the strong absorption properties of water molecules in this electromagnetic range. Based on this, this letter proposes a terahertz all-metal metamaterial humidity sensor incorporating silk fibroin. The sensor is composed of periodically arranged I-shaped annealed copper holes, achieving a refractive index sensitivity of 771.68 GHz/RIU. To further enhance humidity detection sensitivity, silk fibroin, which is exceptionally responsive to water molecules, is selected as the moisture-sensitive coating on the sensor’s surface, research shows that the simulated and experimental results of the humidity sensitivity of this sensor are 0.392 GHz/% and 0.201 GHz/% respectively. The proposed sensor demonstrates excellent performance in aspects such as polarization insensitivity, compact size, and low cost, showcasing significant potential for applications in physical, biological, and chemical sensing.