Dielectric properties of tissues and biological materials: a critical review.

TLDR

The bulk electrical properties of tissues are essential for many bioengineering applications of electric fields or currents and provide insight into the mechanisms governing field–tissue interactions. This paper critically reviews the bulk electrical properties of tissues and other biological materials from DC to 20 GHz, emphasizing the underlying mechanisms. The review covers classical dielectric relaxation principles, recent developments, and advances in counterion polarization, cancer‑versus‑normal tissue comparison, low‑water‑content tissue properties, and macroscopic field‑coupling considerations. It summarizes empirical correlations between tissue water content and dielectric properties and provides a comprehensive table of these properties.

Abstract

We critically review bulk electrical properties of tissues and other biological materials, from DC to 20 GHz, with emphasis on the underlying mechanisms responsible for the properties. We summarize the classical principles behind dielectric relaxation and critically review recent developments in this field. Special topics include a summary of the significant recent advances in theories of counterion polarization effects, dielectric properties of cancer vs. normal tissues, properties of low-water-content tissues, and macroscopic field-coupling considerations. Finally, the dielectric properties of tissues are summarized as empirical correlations with tissue water content in other compositional variables; in addition, a comprehensive table is presented of dielectric properties. The bulk electrical properties of tissues are needed for many bioengineering applications of electric fields or currents, and they provide insight into the basic mechanisms that govern the interaction of electric fields with tissue.