Absorption of Pulsed Terahertz and Optical Radiation in Earthworm Tissue and Its Heating Effect

Mahmoud H Abufadda,Nelson M Mbithi,János Hebling,Gyula Polónyi,József A Fülöp,Priyo S Nugraha,Andrea Buzády,László Molnár

doi:10.1007/s10762-021-00827-1

Mahmoud H Abufadda, Nelson M Mbithi + Show 6 more

Open Access

https://doi.org/10.1007/s10762-021-00827-1

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Abstract

The transmission of THz, near-infrared (1030 nm), and green (515 nm) pulses through Eisenia andrei body wall is studied, which consists of epithelial layer and circular and longitudinal muscles. Samples with the full-body cross-section were also investigated. The transmitted power for the green pulses followed the Beer-Lambert law of exponential attenuation for all thicknesses and tissue structures. Different body wall and body center absorption coefficients were found in case of infrared pulses. In the THz range, the body wall absorption coefficient steadily increases from about 80 cm–1 at 0.2 THz to about 273 cm–1 at 2.5 THz. Numerical estimation indicates that THz pulses of 5-μJ energy and 1-kHz repetition rate (5-mW average power) cause only a small temperature increase of about 0.4 K, suggesting that heating has minor contribution to biological effectiveness.

Highlights

Electromagnetic waves influence the activity of distinct cells and tissues of various species suggesting that probably all life forms respond to light [1]
About 66% of the radiation is transmitted through a 0.33-mm-thick body wall, and only about 22% of the incoming power is transmitted through the 1.5-mm-thick sample containing the whole-body cross-section
Tissue samples taken from Eisenia andrei earthworms of different sizes were used, containing the epithelial layer and the circular and longitudinal muscles

Summary

Introduction

Electromagnetic waves influence the activity of distinct cells and tissues of various species suggesting that probably all life forms respond to light [1]. Journal of Infrared, Millimeter, and Terahertz Waves (2021) 42:1065–1077 electromagnetic waves, e.g., laser light Biological effects of terahertz (THz) radiation have been extensively studied at various levels, from molecules [4, 5] to the organism [6]. With the increasingly widespread use of intense pulsed THz sources, the systematic study of their biological effects became more important and timely. Widely recognized, precise irradiation standards according to biological effectiveness are not yet available. To set up such standards can be very challenging as THz pulses can interact with biological materials in many different ways [7, 8]

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