Thermal-sensitive Dual-band Metamaterial Absorber for Temperature Sensing Applications

We present a dual-band dielectric metamaterial absorber based on Strontium titanate (STO) resonators that exhibits strong thermally tunablility in the microwave regime. The absorber achieves near-unity absorption at two distinct resonance frequencies of 12.18 and 17.51 GHz at 293 K. Both peaks exhibit a noticeable shift toward higher frequencies (blue shift) by approximately 240 and 300 MHz, respectively, as the temperature increases from 293 to 303 K, while maintaining stable absorption intensity. This frequency tunability is achieved by the temperature dependence of STO permittivity, allowing precise control of the resonant frequencies without compromising performance. In addition, the metamaterial absorber exhibits outstanding angular stability. The absorption is maintained above 90% at incident angles up to 60° which is suitable for practical applications with different incident waves. These characteristics emphasize the potential of the STO dielectric metamaterial for advanced thermal sensing devices, tunable filtering, and adaptive electromagnetic wave control.