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Layered Dielectric Characterization of Human Skin in the Sub-Terahertz and Terahertz Frequency Ranges

Silvia Mura, Elisabetta Marini, Maurizio Magarini, Matti Hamalainen, Marco Hernandez

TL;DR

A comprehensive dielectric model of human skin and its cellular constituents is developed across these frequency ranges, providing a physically interpretable description of sub-THz and THz tissue interactions.

Abstract

Sub-terahertz (sub-THz) and terahertz (THz) radiation offer unique opportunities for non-invasive diagnostics and imaging due to their sensitivity to water content and molecular dynamics in biological tissues. In this work, a comprehensive dielectric model of human skin and its cellular constituents is developed across these frequency ranges. The model combines multi-Debye relaxation theory with effective medium formulations to account for intracellular water dynamics and macromolecular relaxation processes. Key cellular parameters, including water content, protein and lipid fractions, and ionic conductivity, are integrated from experimentally validated sources. The proposed framework enables realistic predictions of frequency-dependent permittivity for different skin layers and cell types, providing a physically interpretable description of sub-THz and THz tissue interactions. This approach establishes a foundation for the design and optimization of next-generation diagnostic and imaging techniques operating in these frequency bands.

Layered Dielectric Characterization of Human Skin in the Sub-Terahertz and Terahertz Frequency Ranges

TL;DR

A comprehensive dielectric model of human skin and its cellular constituents is developed across these frequency ranges, providing a physically interpretable description of sub-THz and THz tissue interactions.

Abstract

Sub-terahertz (sub-THz) and terahertz (THz) radiation offer unique opportunities for non-invasive diagnostics and imaging due to their sensitivity to water content and molecular dynamics in biological tissues. In this work, a comprehensive dielectric model of human skin and its cellular constituents is developed across these frequency ranges. The model combines multi-Debye relaxation theory with effective medium formulations to account for intracellular water dynamics and macromolecular relaxation processes. Key cellular parameters, including water content, protein and lipid fractions, and ionic conductivity, are integrated from experimentally validated sources. The proposed framework enables realistic predictions of frequency-dependent permittivity for different skin layers and cell types, providing a physically interpretable description of sub-THz and THz tissue interactions. This approach establishes a foundation for the design and optimization of next-generation diagnostic and imaging techniques operating in these frequency bands.
Paper Structure (17 sections, 11 equations, 5 figures, 3 tables)

This paper contains 17 sections, 11 equations, 5 figures, 3 tables.

Table of Contents

  1. Introduction
  2. Skin Model and Cells
  3. Epidermis
  4. Dermis
  5. Hypodermis
  6. Extracellular Matrix
  7. Computational Modeling of Cellular Permittivity in the sub-THz-to-THz Band
  8. Cell Types and Properties
  9. Extracellular Matrix Composition and Dielectric Properties
  10. Intrabody Wave Propagation Losses
  11. Spreading Loss
  12. Molecular Absorption Loss
  13. Scattering Loss
  14. Simulation framework
  15. Statistical Skin Scenario Definition
  16. ...and 2 more sections

Figures (5)

  • Figure 1: Schematic representation of skin layers and some cell types.
  • Figure 2: Voxel-based 3D representation of skin with randomly distributed spherical cells, scaled by diameter, in (a) epidermis, (b) dermis, and (c) hypodermis.
  • Figure 3: Attenuation due to spreading, absorption, scattering, and the total vs distance, for (a) $f = 100$ GHz and (b) $f = 1$ THz.
  • Figure 4: Absorption coefficient probability density function for (a) $f = 100$ GHz and (b) $f = 1$ THz.
  • Figure 5: Scattering coefficient for (a) $f = 100$ GHz and (b) $f = 1$ THz.