A polarization-insensitive metamaterial absorber for moisture-sensing applications of agriculture products

This study evaluates the metamaterial absorbance and sensing applications of a novel wheel-shaped resonator with triangular spokes. Electromagnetic simulation software, CST Microwave Studio, is used to investigate the numerical results before experimental verification. The proposed absorber exhibits perfect absorption properties at 10.42 GHz, with an absorbability of 99.85%. The designed sensor has been tested for estimating the moisture content of agricultural products, specifically almond kernels. The proposed prototype exhibits an excellent figure of merit and high sensitivity of 58.14 and 11.29 GHz/moisture content percentage, respectively. Additionally, the resonant peak of the sensor shifts by approximately 430 MHz when there is a 4% incremental alteration in the moisture content of the analyzed test sample. The designed sensor shows a high linearity in detecting small variations in moisture level, making it a favorable choice for sensing applications due to its compact size and flat shape.