Layer-dependent electromagnetic field and power deposition in Bacillus anthracis spores: An image-based study at 2.45 GHz

Ghassabi, Amir, Persechino, Martina, Shukla, Shivangi, Liberti, Micaela, Apollonio, Francesca, Williams, Catrin F. ORCID: https://orcid.org/0000-0001-8619-2581 and Choi, Heungjae ORCID: https://orcid.org/0000-0003-1108-293X 2026. Layer-dependent electromagnetic field and power deposition in Bacillus anthracis spores: An image-based study at 2.45 GHz. Presented at: IMBioC 2026, Cosenza, Italy, 26‑29 April 2026. Proceedings of MTT-S International Microwave Biomedical Conference. IEEE, 10.1109/IMBioC69142.2026.11541140

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Abstract

The inactivation of highly resistant pathogens, such as Bacillus anthracis spores, using microwave energy requires a precise understanding of electromagnetic interactions at the cellular level. This work presents a high-fidelity two-dimensional Multiphysics study aimed at characterizing the layer-specific electric field distribution and power deposition within a single spore. High-resolution Transmission Electron Microscopy (TEM) micrographs were used to reconstruct realistic Finite Element Method (FEM) models including the exosporium, spore coat, cortex, and core. Frequency-dependent dielectric properties were described through the Debye relaxation equation to model the electromagnetic response of hydrated biological media at 2.45 GHz. The results highlight a pronounced layer-dependent redistribution of the electromagnetic field and deposited power. The spore coat and cortex emerge as the primary regions of enhanced absorption, exhibiting higher Joule heating density, whereas the inner core behaves as a relative cold spot, with electric field intensity and power deposition reduced to approximately 20–30% compared to the surrounding layers. These findings indicate that microwave inactivation mechanisms may predominantly involve preferential energy localization and structural alteration of the outer protective layers, rather than direct thermal damage to the spore core and its DNA.

Item Type:	Conference or Workshop Item - published (Paper)
Date Type:	Published Online
Status:	Published
Schools:	Schools > Engineering Schools > Biosciences
Publisher:	IEEE
ISBN:	9798331582197
Date of First Compliant Deposit:	31 March 2026
Last Modified:	12 Jun 2026 08:15
URI:	https://orca.cardiff.ac.uk/id/eprint/186108

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