NEW QUANTITATIVE "READING" OF DIELECTRIC SPECTRA OF COMPLEX BIOLOGICAL SYSTEMS

Authors: NIGMATULLIN, RAOUL - KAZAN ST. UNIV., RUSSIA; NELSON, STUART

Submitted to: IEEE Transactions on Instrumentation and Measurement
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/2006
Publication Date: 12/19/2006
Citation: Nigmatullin, R.R., Nelson, S.O. 2006. New quantitative "reading" of dielectric spectra of complex biological systems. IEEE Transactions on Dielectrics and Electrical Insulation. 13(6):1325-1334.

Interpretive Summary: Dielectric properties of materials are those electrical properties that influence the interaction of the materials with electromagnetic fields. For example, the dielectric properties of foods determine how rapidly they will be heated in a microwave oven. These properties can also be utilized with appropriate electronic instruments for sensing moisture content in grain, oilseed, and other agricultural products, because the moisture content is highly correlated with the dielectric properties of the materials. Dielectric spectroscopy is a means for measuring the dielectric properties of materials over a broad range of radio and microwave frequencies. Dielectric spectroscopy data measured on adults of four stored-grain insect species from 200 MHz to 20 GHz at temperatures from 10 to 70 degrees Celsius were furnished to a Russian theoretician for advanced mathematical analysis of their dielectric relaxation characteristics, which determine the dielectric properties of these materials. These analyses identified seven fitting parameters, which, when used with the mathematical relationships employed, provide excellent fitting of the curves for the dielectric properties. Further, the dielectric relaxation behavior of all four species followed the same pattern, thus providing a new description of the dielectric relaxation processes in insect tissues. With further research, the dielectric properties fitting function may be useful in the application of dielectric spectroscopy for sensing quality factors and other important characteristics, which could then be used in the development of new instruments for nondestructive testing of agricultural products. Such new tools would be of value to growers, packers and processors in providing products of improved quality for consumers.

Technical Abstract: Dielectric spectroscopy data from measurements on four insect species from 200 MHz to 20 GHz over a temperature range from 10 to 70 degrees Celsius are described through reduction of numerous micromotions to a few collective motions, recognition of a low-frequency dispersion through ratio presentation format, application of a self-consistent iteration procedure, a separation procedure for types of collective motions, and application of the eigen-coordinates method for calculation of seven fitting parameters. Use of such fitting parameters to describe the total system relaxation processes quantitatively should enable practical uses of dielectric spectroscopy for measuring desired qualities or characteristics of biological and other complex materials.