A Broadband Versatile Exposure System for Dielectric Spectroscopy Applications

This work presents the numerical and experimental characterization of a broadband exposure system for dielectric spectroscopy applications [1,2]. The system is based on a grounded coplanar waveguide (GCPW), modeled in COMSOL Multiphysics, incorporating transitions to 50-ohm coaxial lines to ensure proper impedance matching [1,2]. S-parameters (S11, S21) were measured and analyzed across different configurations, including the empty device and the device loaded with a modified 35 mm Petri dish, filled with different liquid samples (distilled water and physiological solution) at varying volumes (78 μL, 100 μL, 1 mL, and 2 mL). The simulations provided insights into the system’s response, demonstrating its capability to accurately differentiate between different dielectric properties. To validate the simulation results, experimental measurements were conducted using a Vector Network Analyzer (VNA) in the frequency range from 50 MHz up to 4 GHz. Initially, the empty device was tested to confirm its stability and ensure that its response closely matched the simulations. The next step involved measurements with an empty Petri dish, followed by repeated measurements incorporating liquid samples at different volumes. A modified 35 mm Petri dish, featuring a small well at its center, was introduced to achieve the lowest possible measurable volume, allowing for improved sensitivity and precision in dielectric discrimination. The measurements showed strong agreement with simulations, confirming the device’s reliability in capturing frequency-dependent variations in dielectric properties. Preliminary results demonstrated that the system effectively differentiates between the empty device, the device with an empty Petri dish, and the device with liquid samples. When the Petri dish was filled with higher liquid volumes (1 mL and 2 mL), distinct variations in S11 and S21 parameters were observed in the 2–3.5 GHz frequency range, depending on the type of liquid used. These results indicate the potential of the system for detecting subtle dielectric contrasts, reinforcing its suitability for biomedical and diagnostic applications. This research lays the foundation for future developments in dielectric spectroscopy, particularly in detecting and analyzing biological materials with high sensitivity. The next phase of this work will focus on using the system for the inactivation of viruses and living cells, further enhancing its applications in biomedical research and diagnostics.