Figure 1. Conceptual schematic comparing nanowarming “volumetric” vs. convective “boundary” rewarming.

An alternating magnetic field in the RF frequency range (63 kA/m and 185 kHz) excites the magnetic nanoparticles within the CPA distributed in the organ vasculature. Heat is generated through hysteresis losses in the nanoparticles, which results in rapid and uniform rewarming. Notably, the fields in this frequency range do not cause significant direct heating of the biospecimen, so uniformity of heating is driven by the distribution of nanoparticles. Convective methods (right) typically fail to achieve rewarming rates faster than the CWR, causing damage from ice crystallization. Additionally, convective rewarming methods suffer from non- uniformity as the surface is rewarmed at much faster rates than the interior, leading to thermomechanical stresses and cracking.