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Title: LOW-FREQUENCY DIELECTRIC DISPERSION FROM ION PERMEABILITY OF MEMBRANES

Author
item KUANG, WENSHENG - UNIV GA DEPT AGRIC ENGR
item NELSON, STUART

Submitted to: Journal of Colloid and Interface Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/29/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: The dielectric properties (electrical characteristics) of biological materials can be used with electronic instruments to sense quality of agricultural products if there are suitable relationships between their dielectric properties and important quality characteristics. Testing moisture content in grain is a good example. In exploring low-frequency electrical characteristics of products such as fruits and vegetables, impedance measurements have revealed very high values of certain dielectric properties. The study reported in this paper was carried out to explain the basis for some of these observations, which are associated with the behavior of ion conduction through membranes in biological tissues. A new low-frequency dispersion phenomenon was observed and studied with artificial plastic membranes. The magnitude of the dispersion (the change in dielectric properties with change in frequency of the applied electric field) was found to be associated with the number of pores in the plastic membranes, the size of the pores, the thickness of the membrane, and the concentration of the salt solution used as an electrolyte. The studies provide new basic information that may be useful in helping to understand the low-frequency behavior of membranes and biological materials, indicating also potential usefulness of electrical measurements for determining pore size or pore numbers in membranes.

Technical Abstract: Low-frequency dielectric behavior of membrane/electrolyte systems was studied with artificial membranes and NaCl electrolyte of various concentrations. A low-frequency dielectric dispersion or relaxation, which is associated with membrane pores and membrane permeability, was observed and investigated. A qualitative explanation is proposed. Membrane structure characteristics, such as thickness, pore size and number, were found to affect significantly the low-frequency dielectric dispersion, which indicates some potential applications for low-frequency dielectric measurements in membrane- or tissue-related areas.