Permittivity of biological tissue is a critical issue for studying the biological effects of electromagnetic fields. Many theories and experiments were performed to measure or explain the permittivity characteristics in biological tissue. In this paper, we investigate the permittivity parameter in biological tissues via theoretical and experimental analysis. Firstly, we analyze the permittivity characteristic in tissue by using theories on composite material. Secondly, typical biological tissues, such as blood, fat, liver, and brain, are measured by HP4275A Multi-Frequency LCR Meter within 10 kHz to 10 MHz. Thirdly, experimental results are compared with the Bottcher-Bordewijk model, the Skipetrov equation, and the Maxwell-Gannett theory. From the theoretical perspective, blood and fat are regarded as the composition of liver and brain because of the high permittivity in blood and the opposite in fat. Volume fraction of blood in liver and brain is analyzed theoretically, and the applicability and the limitation of the models are also discussed. These results benefit further study on local biological effects of electromagnetic fields.

Dielectric parameters vary with frequencies are important properties of biological systems, which determine the absorption rates of electromagnetic radiation in human body. Two phase dielectric model is considered to investigate the dielectric properties of human blood in this paper. This paper systematically calculates the body's specific absorption rate of electromagnetic fields at low frequencies based on the dielectric properties obtained from the Debye model. This study could lay foundation not only for the theoretical basis for further study on electrical properties of biological tissue, but also for the exposure limits of health standard on electromagnetic radiation.