Electromagnetic-based hyperthermic therapies induce a controlled increase of temperature in a specific tissue target in order to increase the tissue perfusion or metabolism, or even to induce cell necrosis. These therapies require accurate knowledge of dielectric and thermal properties to optimise treatment plans. While dielectric properties have been well investigated, only a few studies have been conducted with the aim of understanding the changes of thermal properties as a function of temperature; i.e., thermal conductivity, volumetric heat capacity and thermal diffusivity. In this study, we experimentally investigate the thermal properties of ex vivo ovine liver in the hyperthermic temperature range, from 25 °C to 97 °C. A significant increase in thermal properties is observed only above 90 °C. An analytical model is developed to model the thermal properties as a function of temperature. Thermal properties are also investigated during the natural cooling of the heated tissue. A reversible phenomenon of the thermal properties is observed; during the cooling, thermal properties followed the same behaviour observed in the heating process. Additionally, tissue density and water content are evaluated at different temperatures. Density does not change with temperature; mass and volume losses change proportionally due to water vaporisation. A 30% water loss was observed above 90 °C.

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Nasogastric tube insertion is a standard procedure but with potentially fatal consequences if misplaced. Many bedside methods have been proposed for identifying misplacement including magnetic inductive coupling. This study aims to identify the coil design limitations for nasogastric tube placement confirmation using magnetic inductive coupling. The fundamental limits on the coil sizes and detection distances are identified based on the anatomical understanding. Candidate designs are simulated and fabricated, and key parameters such as coil radius and penetration depth are examined. Specifically, the mutual inductance and coupling factor between the coils in the candidate designs are both calculated and measured with respected to distance. This work highlights that a small coil of up to 3 mm in diameter could be integrated into a nasogastric tube without impairing clinical function. These preliminary results suggest that magnetic inductive coupling is a promising approach for nasogastric tube localisation, however, optimisation of the detector coil size could improve localisation performance.