Quantitative assessment of dielectric parameters for membrane lipid bi‐layers from RF permittivity measurements

Abstract

In this article, we propose and validate theoretical and experimental methods to quantitatively assess the Debye dielectric model of membrane lipid bi-layers. This consists of two steps: permittivity measurements of biological solutions (liposomes), and estimation of the model parameters by inverse application of the Effective Medium Theory. The measurements are conducted in the frequency domain between 100 MHz and 2 GHz using a modified coaxial connector, at the temperatures of 27 and 30 degrees C. Estimations have been performed using a three-layered model based on the Maxwell-Wagner formulation. Debye parameters (mean value +/- standard error) found from fitting experimental data are: epsilon(s) = 11.69 +/- 0.09, epsilon(infinity) = 4.00 +/- 0.07, f(relax) = 179.85 +/- 6.20 MHz and epsilon(s) = (1.1 +/- 0.1) x 10(-7) S/m. This model can be used in microdosimetric studies aiming to precisely determine the E-field distribution in a biological target down to the single cell level. In this context the use of an accurate membrane dielectric model, valid through a wide frequency range, is particularly appropriate.

A Microdosimetric Study of Electropulsation on Multiple Realistically Shaped Cells: Effect of Neighbours

“…Values for the extracellular medium (phosphate-buffered saline, PBS) characteristics were obtained as previously reported (Merla et al 2009, Piuzzi et al 2013. The electrical and geometrical values for all compartments were chosen to be in accord with values presented in literature (Merla et al 2012;Denzi et al 2013Denzi et al , 2015bGowrishankar and Weaver 2006;Ermolina et al 2000).…”

Open-Ended Waveguide Measurement and Numerical Simulation of the Reflectivity of Petri Dish Supported Skin Cell Monolayers in the mm-wave Range

“…Open-ended reflectometry in the microwave and mm-wave frequency range, is used in some industrial applications for non destructive measurement of dielectric properties of materials and dielectric slab thickness, for inspections of disbond and delaminations in stratified composite materials [17][18][19], for crack detection in metals [20]. Open-ended waveguide technique has been also applied in the biological field for dielectric permittivity measurement of biological tissues and membrane lipid bilayers in the microwave range [21,22] and for skin dielectric permittivity measurement in vivo, in the millimeter wave range [23,24]. Recently, microwave (0.3-6 GHz) and mm-wave reflectometry has been proposed as a potential diagnostic tool for non invasive skin health assessment.…”

Nanometer-Resolved Radio-Frequency Absorption and Heating in Biomembrane Hydration Layers

“…In fact, our simulated parallel spectra qualitatively match experimental absorption studies on planar membrane stacks 19 and vesicle solutions. 20 What is less expected is (i) the pronounced anisotropy with a drastically reduced perpendicular absorption strength which should be experimentally observable using surface-sensitive Specific Absorption Rates in Planar and Curved Cell Geometries. The absorption rate of electromagnetic radiation follows from the solution of Maxwell's equations which depend on the dielectric spectra.…”