TEM Cell With a High-Transparency Aperture for Homogeneous Microwave Absorption and Real-Time Viewing of Thermoelastic Expansion of Tissue

In this study we simulate and evaluate a transverse electromagnetic cell (TEM) for dosimetry applications in the UHF band with design modifications to allow real-time monitoring of tissue expansion due to microwave pulse absorption. We introduce an aperture for high-speed microscope-based imaging inside the waveguide and use simulations to assess the aperture' s impact on power absorption homogeneity and dosage level in tissue samples positioned at the site of the aperture. We consider both transparent, non-conductive borosilicate and semi-transparent, conductive indium tin oxide-coated glass plates covering the aperture. Our simulation results indicate a borosilicate covering provides optimal power absorption homogeneity when the tissue sample is smaller in diameter than the aperture. Analysis of the simulation results enabled us to construct an optimized TEM cell with a borosilicate-glass-covered aperture and experimentally verify that it maximizes dosage in the tissue sample. This modified TEM cell is expected to be an essential component in an experimental platform for observing and recording the macroscopic, dynamic thermoelastic expansion of tissue induced by pulsed microwave exposure.