Rapid electromagnetic warming of cells and tissues

We describe a system for thawing frozen cell suspensions and tissues by ele ctromagnetic absorption. A 25-ml sample is heated in a cylindrical resonant cavity, which is excited in three modes all close to 434 MHz. Maximum warm ing rates are over 10 degrees C/s (600C/min), and a frozen sample may be br ought from -65 degrees C to room temperature in <30 s, with final spatial d ifferences of <20 degrees C. Samples may be frozen externally, or cooled wi thin the cavity at typically 1 degrees C/min, We have also used the resonan t cavity to measure the permittivity and conductivity of the sample at temp eratures from -83 degrees C to +8 degrees C. By measuring the heat capacity of the sample, we have calculated the power deposited in it as a function of its temperature. The system is currently being used to investigate the e ffect of warming rate on cell survival.