RF Module (emw): Frequency-domain spectroscopy of a single biological cell

Posted 2025/12/17 4:07 GMT-5 RF & Microwave Engineering, Studies & Solvers Version 6.4 1 Reply

Giulia Risca

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Hello, I am working with COMSOL Multiphysics (v. 6.4) – RF Module (Electromagnetic Waves, Frequency Domain) because my frequency of interest is 2.45 GHz. My model consists of a single biological cell, with a realistic geometry imported from CAD. The objective is to study the electromagnetic response of the cell (e.g. transmembrane electric field, SAR, polarization) when exposed to an RF field at 2.45 GHz. I am trying to understand how to properly “deliver” or excite the electromagnetic field on the cell using the RF Module, in a way conceptually similar to how Terminal conditions are used in the AC/DC Module. In other words, I would like the field to be present, but without explicitly modeling a physical RF source (antenna, waveguide, coaxial cable, etc.) and without imposing boundary conditions directly on the cell membrane. I have considered the following approach: * Electromagnetic Waves, Frequency Domain (emw); * Scattered field formulation; * Background electric field (plane wave excitation); However, I am still unsure how to correctly apply and interpret this excitation in practice, especially with respect to the physical meaning of the background field and how it relates to a real RF exposure at 2.45 GHz. An alternative idea I initially had was the following: * Surround the cell with a box representing the extracellular medium * Apply a Port condition on one face of the box * Apply Perfect Electric Conductor boundary conditions on the other faces The intention was to generate a propagating electromagnetic field inside the box and expose the cell to it. However, I am not sure whether this setup is physically correct or recommended, and whether Ports can be used in this way when no actual transmission line or waveguide is modeled. Therefore, my questions are: 1. What is the recommended way to excite an RF field at 2.45 GHz on a single cell using the RF Module, without explicitly modeling an RF source? 2. Is scattered field formulation with background electric field the correct approach for this type of problem, and if so, how should it be properly implemented? 3. Is the idea of using a box with a Port on one face and Perfect Electric Conductor on the others physically meaningful in this context, or should Ports only be used when modeling real waveguides or transmission lines?

Any guidance, best practices, or references to similar models would be greatly appreciated.

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1 Reply Last Post 2025/12/17 7:45 GMT-5

Andreas Bick COMSOL Employee

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Posted: 3 hours ago

Updated: 3 hours ago

Hi.

If the cell is located in a homogenous domain, you could use this model as a reference. It uses a scattered field formulation, so basically what you describe.

https://www.comsol.com/model/optical-scattering-off-a-gold-nanosphere-14697

You can read more about the scattered field formulation here:

https://doc.comsol.com/6.4/docserver/#!/com.comsol.help.rf/rf_ug_modeling.05.11.html

Regards, Andreas

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