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  • Installing Sim4Life and configuring licenses

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    M
    Hi, yes, we have new agent in China and the contact email is zmt_china@163.com.

  • Working with CAD models

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    C
    I've been comparing running EMLF simulations, in some cases assigning anode=100V and cathode = 0V, vs. anode = 50V and cathode = -50V. Theoretically, these should produce the same results, as the potential difference is the same in each, but that's not what I am finding. It seems as if a reason for this are the 'holes' in the simulation, which are assigned with the conductivity of the background material, which is air. This produces large regions of effectively 0 S/m conductivity within the model, leading to voxels that are solved as 0V throughout the simulation. These voxels then alter the path of current within the model, which would otherwise be limited to flowing between electrodes, particularly if a cathode is assigned as 0V for instance. Is the answer to this filling the models with a material that could be assigned as 'fat', as is done in the following paper? https://www.nature.com/articles/s41551-026-01684-w What else could be making these choices of electrode boundary conditions nonequivalent? @bryn would love your input on this.

  • Working with models from the Virtual Population

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    R
    Hello Silvia, Thank you for your reply and for clarifying this. Noted with thanks. Robert

  • FDTD, Low-Frequency, Neuron, Mode-Matching, Flow, Acoustics, etc...

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    V
    Hello, I am setting up an LF Electro Ohmic Quasi-Static simulation using the DUKE_POSABLE 3.2 model. I have placed two solid spherical electrodes in contact with the body and applied Dirichlet boundary conditions. After voxelisation, the electrodes appear hollow or lattice-like, as shown in the attached screenshots, even though the original geometries are solid. I used a local 1 mm grid for the electrodes, while the anatomical model has a maximum grid step of 2 mm. Could you please explain what may be causing this appearance? Is it only a visualisation effect, or does it mean that the electrode interiors have not been filled with voxels? If the electrodes are actually voxelised as hollow structures, could this affect the electrical contact with the tissue, including the calculated current distribution or contact impedance? Also, is there a way to check whether the electrode material has been correctly assigned throughout the entire electrode volume? Thank you. Here is the screenshort of the voxel: [image: 1789648394768-screenshot-2026-09-17-104009.png] Screenshort on simulation settings: [image: 1789648532529-screenshot-2026-09-17-104234.png]

  • Postprocessing results

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    B
    The text exporter is just called 'FieldDataTextExporter' instead of 'MatlabExporter'. However, I would first recommend that you try my suggestion of using the GUI to add a text exporter, and then right-click the analysis tree to generate the equivalent code. This is the best way of discovering the API equivalent of UI features.

  • Scripting interface for Sim4Life

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    R
    thanks Robin!

  • Running Sim4Life over a network

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    ofliO
    Hi, Please allow me to share here the response we sent you via the Sim4Life support email so that other users can benefit from your questions. The default machine provides 500GB of storage, and you are running out of space for this project. If your results require more than 500GB, consider upgrading to a higher-tier machine with greater storage capacity. Alternatively, you could reduce the size of your simulation project by splitting it into multiple smaller simulations. This would allow you to continue using the default tier. Additionally, you might optimize your sensor settings, such as by creating smaller sensors and recording data for specific volumes of interest, rather than using an Overall Field sensor.
  • L

    Cannot read document verion

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    L
    I have two versions installed (6.2.2 and 7.00) and I tried opening the file with both. I have now deleted the smash file that wasn't working and started over, but if it happens again, I will try the import option- thanks!
  • V

    Bone identification using RF signals

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  • S

    The file I created with Sim4Life light cannot be opened.

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    brynB
    If you don't have a full version, i think (untested) you can still recover the model by importing the smash file in the modeling tab.
  • P

    'Point Sensor Tool' is not available

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    Sorry, don't have S4L with neuron available at the moment, but I looked at the tutorial and it seems to have changed. When you create the sensor settings can you try to drag and drop the axon to the sensor setting and then chose the section name? (That was the old way of doing it) Still, you should be able to run the simulation without a point sensor.. Sorry can't help more
  • L

    Everytime I'm doing a too complex simulation the file is lost

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    L
    I am using Sim4Life 6.2.1.4972. It happened once when I've had put a high "maximum number of samples" in the time domain (200 I think) with the acoustic head tutorial that I changed a bit, by putting 2 transducers instead of 1. Another time it was weird because it happened with a SEFT targeting a square of skin, which was rather simple but it did crash again. My simulation was probably wrong in a way, but it didn't throw and error and just stopped. But now that I am applying @gbgbha advices, it is fine and thanks for the tip ! I'll try for the file that I lost
  • R

    Why does TRP exceed input power(Antenna)?

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    S
    The TRP is computed in a different way than the input power. Both ways are mathematically correct and would both be "exact" if there were no numerical errors. In any FDTD simulation, however, there are spatial (finite grid) or temporal (finite time step) discretization error. What you are seeing in this half-wave dipole example, is that those discretization errors are larger than the precision you would require to distinguish TRP from input power (because the radiation efficiency is very high in this case, there is almost no difference between TRP and input power). To solve this "problem", either you accept that the simulation results are accurate enough for your needs (the warning is a simple consistency check) or you increase the precision of the simulation. You can do so by increasing the grid resolution, the overall convergence level and the resolution of the far-field sensor. This will be computationally expensive, though. To help you understand, you could try to add some lossy media in your (coarse) simulation (e.g. place the dipole next to a phantom or any other dielectric). The simulation will not be more precise, but the numerical errors will be less "obvious" because they will be dwarfed by the losses occurring in the dielectric. The TRP will be lower than the input power and the warning will not be triggered. I hope this helps.
  • D

    The effect of electromagnetic field on the temperature of human tissues

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  • A

    S4L is unable to read and load my project

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    ali.oezenA
    THank you very much for the hints.
  • E

    How to export images from Sim4Life Analysis Results

    image export png jpeg
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    M
    That works! If it's for a 2D plot, you can always right click and export the data to an excel or csv file and then work with that if you'd prefer
  • A

    Optimal performance

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    The full version has the same performance as the Light version: it can just deal with bigger problems. Note that the low-frequency solvers are not GPU-accelerated, so if you are using that the GPU is anyway not used. If you are using the FDTD solver instead, it is accelerated by the GPU but its performance might be severely affected by the frequency of your simulation (the lower the frequency, the more iteration the FDTD method has to do in order to reach convergence). If you are in a regime where the quasi-static approximations hold, I would strongly advise you to use the LF solvers.
  • J

    Editing the excitation signal

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    S
    I think your signal was fine, but your settings for the Field Sensor need to be changed.
  • J

    Invalid Bounding Box Error

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    S
    2kHz will probably not be feasible in most propagating media, because the wavelength will simply be too large compared to the grid resolution your geometry requires (leading to unreasonably large time steps). You might want to check for e.g. what your grid look like, especially the padding at the boundaries of your computational domain.
  • H

    This topic is deleted!

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  • S

    CEM43 / Arrhenius Thermal Damage

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  • S

    how to model a bent wire with a fixed length?

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    S
    Thanks for the code. Actually I need to model some wires with the fixed length, with one part in the brain in different spots and the remaining out of the brain, It takes a long time to model each one and I'm looking for a way to make them in a shorter time. Thanks.
  • S

    grid resolution of wire and insulation

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    S
    Thanks for your reply.