Multifrequency method for dielectric monitoring of cold-preserved organs

Abstract

To answer a growing need for non-invasive monitoring of biological organs, we have developed an automated system capable of repeated dielectric measurements over the frequency range 10 kHz-100 MHz. Further, we propose a novel method of data analysis that may convert the acquired, individual dispersion curves into a diagram of the time course of specific phenomenological parameters, such as the characteristic frequency. By using this new procedure, unattended, long-term monitoring of temporal changes in the dielectric behaviour of excised liver lobes stored at 4 degrees C was successfully realized. The 'multifrequency' method presented here was definitely superior to the conventional 'fixed-frequency' method in providing reliable results.

Fundamentals of Biomedical Applications of Biomorphic SiC

“…Moreover, multi-frequency monitoring of impedance has the advantage of yielding to more comprehensive empirical mathematical characterizations (i.e. the Cole model; Cole, 1940) that can provide additional information through the analysis of derived parameters and improve the reproducibility of results (Raicu et al, 2000). Gomez et al (Gomez et al, 2006) examined the feasibility of producing SiC-based needleshaped impedance probes for continuous monitoring of impedance and temperature in living tissues.…”

Biomimetic Membranes with Aqueous Nano Chanels but without Proteins: Impedance of Impregnated Cellulose Ester Filters

“…Apparent dielectric permittivity increases by 1000 times in a cold-preserved liver when log f decreased from 8 to 4. 60 Skeletal muscle shows R dispersion below 1 kHz, β dispersion with a frequency of about 100 kHz and γ dispersion at higher frequencies. 61 During ischemia R dispersion disappears, which was explained by an increase of conductivity in the membrane of sarcoplasmic reticulum.…”

“…In this case a series of four characteristic frequencies were found in the range between 0.1 Hz and 5.5 kHz. Apparent dielectric permittivity increases by 1000 times in a cold-preserved liver when log f decreased from 8 to 4 …”

The use of electric fields in tissue engineering

“…[1][2][3] Measurements on natural tissues can give information on for example the orientation of the cells in the tissue, tissue fat content, moisture content, tissue damage through thermal or other effects, tissue freshness-or time since death. [4][5][6] Also, pronounced differences exist between the electrical properties of some cancerous and non-cancerous tissues. 7 An important potential application of dielectric measurements on engineered tissues is the on-line and continuous measurement of the cell concentration and its distribution within a tissue construct.…”