High Resolution Ultra-Violet Radiation Detection Using TNT-Integrated Wireless Passive Microwave Resonator

This work presents high-resolution detection and quantification of ultraviolet (UV) radiation using a passive split-ring resonator (SRR) tag integrated with TiO₂ nanotube (TNT) membrane. The passive tag was electromagnetically coupled to an active feedback-assisted SRR reader, which compensated the dielectric and radiation losses of the coupled resonant sensor and increased the quality factor (Q) from 87 (passive) to 700 (active). The proposed sensor operated at the frequency span of 2.5 GHz to 3.2 GHz, where the passive tag was placed 3 cm above the SRR reader. UV exposure of TNT changed the dielectric properties (permittivity and conductivity) of the membrane and consequently was reflected as variation in the resonant amplitude and frequency of the sensor. Measured results demonstrated five times higher sensitivity for active sensor (0.22 dB/Wcm-2) compared to the passive counterpart (0.04 dB/Wcm-2). Due to improved sensitivity, this robust microwave-based UV sensor is suitable for various industrial and biomedical applications.