Microwave metamaterial sensor for label-free dielectric characterization of biological equivalent media

The growing demand for rapid, compact, and label-free biomedical sensing has motivated the development of highly sensitive electromagnetic biosensors. In this work, a microwave resonant metamaterial-based biosensor is proposed for refractive index (RI) sensing of biological-equivalent media modeled using dielectric properties representative of blood- and hemoglobin-related materials. The sensor is designed using a surface-resonant micro strip architecture composed of rectangular resonators that enhance electromagnetic confinement and field–matter interaction. Numerical simulations and experimental validation are performed at a resonance frequency of approximately 2.1 GHz. The sensing mechanism is evaluated through resonance frequency shifts induced by variations in the effective refractive index of the analytes. Systematic parametric analysis is conducted to optimize the geometric configuration and improve sensing performance. The optimized structure achieves a maximum sensitivity of 600 MHz/RIU, an average quality factor of 22.46, and maximum figure of merit of 5.34. The strong field localization and stable resonance behavior confirm the robustness of the proposed design under different material loading conditions. The results demonstrate that the proposed sensor provides a compact platform for microwave dielectric characterization of biological-equivalent media and may serve as a preliminary framework for future experimental biosensing systems.