Electromagnetic rewarming: the effect of CPA concentration and radio source frequency on uniformity and efficiency of...

The relevant dielectric properties of a practical perfusate formula have been measured at radiofrequencies from 27 to 2954 MHz and temperatures from -75 to +25 degrees C. Both dimethyl sulfoxide and 2,3-butanediol were investigated as the cryoprotectant component at concentrations from 15 to 50%. The dielectric properties are considered in terms of new indices which characterize uniformity of heating, the power delivered and the efficiency of heating, and the avoidance of localized thermal runaway during very rapid heating. It becomes clear that a compromise must be accepted between nonuniformity of heating at the higher frequencies and inconveniently low power delivery at the lower frequencies. The choice of CPA and the concentration are found to be not very significant in these respects.