Research Article Culture Medium Geometry: The Dominant Factor Affecting In Vitro RF Exposure Dosimetry Alessandra Paffi, 1 Francesca Apollonio, 1 Micaela Liberti, 1 Asher Sheppard, 2 Giorgi Bit-Babik, 3 and Quirino Balzano 4 1 Sapienza University of Rome, 00184 Rome, Italy 2 Asher Sheppard Consulting, 4960 Hoen Avenue, Santa Rosa, CA 95405, USA 3 Motorola Solutions, Inc., Plantation, FL 33322, USA 4 University of Maryland, Rm 2134, Kim Building, College Park, MD 20742, USA Correspondence should be addressed to Quirino Balzano; qbalzano@umd.edu Received 13 November 2014; Accepted 30 December 2014 Academic Editor: Diego Caratelli Copyright © 2015 Alessandra Paf et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Biological experiments that expose living cells or tissues to RF energy must have an aqueous medium to provide essential water, ions, nutrients, and growth factors. However, as we show here, the medium inherently functions as a receiving antenna that conveys RF energy to the biological entity in a manner entirely determined by exposure vessel geometry, orientation to the incident RF fux, frequency, and dielectric properties of the medium. We show for two common experimental arrangements that basic antenna theory can predict electromagnetic energy patterns that agree well with those otherwise obtained by computationally intensive methods that require specialized resources. 1. Introduction Over the last half century researchers have exposed cell preparations to RF electromagnetic (EM) energy to explore mechanisms of interaction of living cells with EM felds [1]. Early experiments frequently were conducted by exposing biological preparations to an incident EM wave of given power density. However, the pattern of the RF feld exposure of cells within the medium was not investigated for lack of analytical tools, leaving investigators with little knowledge of the distribution of energy absorbed by the cells under test. Unless there is a clear understanding of the physics of EM felds, it is possible to miss the overall character of RF absorption by a biological preparation. Te last two decades [2–4] have seen substantial advance- ments in theoretical and experimental dosimetry. Minimal requirements for exposure systems have been established [5] and are now widely accepted. Te detailed distribution of absorbed energy inside an exposure vessel requires computer algorithms that accurately model the fne details of exposure systems and exposed samples. One such numerical method is the fnite diference time domain (FDTD) algorithm based on numerical procedures to solve the EM problem within a region of space [6]. Te FDTD method performs a point-by-point evaluation of the EM felds whereas the analytical approach proceeds from the frst principle, Faraday’s law, in describing the inter- action between the felds and the medium. Consequently, the analytic models reveal the physical events underlying the computational results. Tis paper aims to show that the culture medium of a biological preparation not only supports cell metabolism but also conveys the EM energy absorbed by the tissues and cells under test, illustrating the usefulness of the concept that the medium is an antenna whose geometric and dielectric prop- erties entirely determine the biologically relevant exposure. Te cells themselves have a passive role as absorbers of EM energy from the local environment. Equivalently, the cells can be considered as a distributed load of a dielectric antenna consisting of the medium in which they are embedded. Tis paper also presents analytical approaches that are simpler than numerical FDTD computations and sufciently accurate Hindawi Publishing Corporation International Journal of Antennas and Propagation Volume 2015, Article ID 438962, 10 pages http://dx.doi.org/10.1155/2015/438962