26-01-2023 | Posted by Joaquín Martí
Bioelectromagnetics covers the interaction of electromagnetic (EM) fields with the human body. It is a crucial topic for many imaging and treatment medical devices. Safety regulations also make it a concern for many other products, from smartphones to electric cars. The human body is complex and includes materials with a wide range of EM and thermal properties, requiring specialised modelling and simulation tools. This post is adapted from one by Dassault Systèmes (DS).
CST Studio Suite, the EM simulation tool, and other multiphysics tools from the SIMULIA brand of DS can be used to tackle those challenges. Powerful design tools and realistic material models can capture the rich details of both electronic devices and the human body. High-performance solvers can simulate EM fields in the complex environment of the body rapidly and accurately.
The complexity of the human body requires very detailed simulation models. SIMULIA software supports both polygonal and voxel models, which can be used to set up realistic scenarios.
A family of simulation-ready human body models representing different body types is available. The technology also includes accurate bio-heat models, that incorporate thermoregulation effects such as blood flow and metabolic heat, to simulate how EM fields heat the body.
For life sciences
Medical devices such as magnetic resonance imaging (MRI), microwave imaging, and diathermy all use EM fields. Designing an efficient, high-resolution MRI scanner, for example, requires an understanding of multiple overlaying fields at a wide range of frequencies, from the static magnetic field to the radio frequency pulse, and their complex interaction with body molecules.
EM simulation models the propagation of waves through the body, and their interaction with tissues, whether this is a desired therapeutic effect or an unwanted side effect.
Engineers and physicians can use its results to understand how energy is absorbed by the body and to validate device designs and treatment protocols. For example, to verify the safety of implants and devices like pacemakers during a scan, or to calculate the heating pattern and safe power levels for a course of RF diathermy.
The MRI solution from SIMULIA models all the different coils and their control circuits, together with the patient, for a full simulation of the scan procedure. This helps MRI technicians to tune the coils for taking optimal images, given the structure of the body.
For high-tech and industrial equipment
At radio and microwave frequencies, EM waves can be reflected, refracted or absorbed by the human body. This causes performance problems for portable and wearable devices such as smartphones and smartwatches, where the exact position of the hand can impact antenna performance significantly.
Also, safety regulations limit the radio frequency radiation exposure from many consumer and industrial devices. This is often quantified by the Specific Absorption Rate (SAR), a measure of the power absorbed by body tissues. Other fields, such as high-power transmitters and radars, have similar radiation hazard (RADHAZ) KPIs, and human exposure is also a concern for low frequency fields around power lines and wireless charging points.
The performance of a device in the vicinity of the body can be simulated and any potential issues mitigated before committing to a physical prototype, thereby reducing future risks. KPIs such as SAR are automatically determined and any violations of specified limits are highlighted.
