The Sim4Life companion for implant WPT.
Sim4Life answers whether an implant's power link is safe in a human body. AirInduct Sim answers an earlier question — which coil pair delivers enough coupling at that depth — in seconds, so the expensive anatomical runs start from a sized design.
Last reviewed: October 2026
What Sim4Life does well
Sim4Life, from ZMT Zurich MedTech, is built to simulate physics inside the human body. Its full-wave EM-FDTD solver handles graded, multi-resolution grids with over a billion voxels, and its quasi-static EM-QS family covers electrostatic, magnetostatic and magneto-quasi-static problems with finite elements — the regime most implant power links live in.
What sets it apart is anatomy. It ships the IT'IS Foundation's Virtual Population, more than 25 detailed human models across ages, sizes and pregnancy, with tissue properties attached. On top of the field solvers sit thermal, neuronal dynamics and MRI implant-safety tools, which is why regulatory and medical-device teams use it to show SAR, induced fields and heating stay within limits.
Where AirInduct Sim is faster for WPT coils
A Sim4Life study starts with a body model, a placement and a tissue grid. That is the right cost for an exposure result, and the wrong cost for choosing between a 20 mm and a 25 mm receive coil. AirInduct Sim works in air with closed-form Biot–Savart fields and Neumann mutual inductance, so link sizing takes seconds:
- Coupling k and mutual inductance M against implant depth and lateral offset in one sweep.
- Small planar spirals (DTC) and Helmholtz pairs as presets, tuned by a genetic optimizer.
- SPICE export of L and M to design the rectifier and matching network.
- KiCad and DXF export for a flexible PCB coil.
- An AI Copilot that runs the real solver, and an MCP server for agents.
It is free to start: the free plan covers the Helmholtz topology with 3 simulations a month, and AirInduct Pro unlocks every topology, the AI Copilot and unlimited runs (see pricing).
Sim4Life vs AirInduct Sim at a glance
Two tools for two stages of an implant power link: sizing in air, then exposure in tissue.
| Criterion | AirInduct Sim | Sim4Life |
|---|---|---|
| Solver method | Closed-form Biot–Savart field + Neumann mutual inductance, no mesh | Full-wave EM-FDTD plus quasi-static EM-QS solvers (FEM on voxel and unstructured meshes) |
| 3D | Full 3D B and H fields in air, interactive 3D plots | Full 3D, in heterogeneous anatomical models |
| Install | None — runs in the browser, plus iOS and Android apps | Desktop on Windows 11; Sim4Life.web and Sim4Life.lite run in the browser |
| Licence / price model | Free plan + Pro subscription | Commercial desktop licences, quote-based; pay-per-use Sim4Life.web; free Sim4Life.lite for students |
| Time to first result | Seconds from a topology preset | Hours: place the coil in a body model, assign tissues, grid, solve |
| WPT outputs (L, M, k) | Self-inductance, mutual inductance M and coupling k on every run | Fields and port quantities; link parameters are not its focus |
| SAR and tissue exposure | Not computed — AirInduct Sim does not model tissue | Core strength: SAR, induced E-field and current density, thermal rise |
| Anatomical models | None | IT’IS Virtual Population: 25+ adult, child, elderly and pregnant models |
| Implant safety tools | None | MRI implant safety (IMSAFE, IMAnalytics), neuronal dynamics, thermal |
| Export | PDF report, KiCad, DXF, SPICE | Project files, field data and analysis reports |
| AI assistance | AI Copilot that drives the app and runs the real solver; MCP server for agents | Python scripting API |
Competitor details are taken from public vendor pages and documentation, last reviewed October 2026. Product names are trademarks of their respective owners and are used only to identify them. AirInduct is not affiliated with, endorsed by or sponsored by any of these vendors.
When to stay with Sim4Life
Any claim about tissue belongs in Sim4Life. SAR, induced electric field against ICNIRP or IEEE limits, temperature rise around the implant, nerve stimulation and MRI conditional labelling all need an anatomical model, and AirInduct Sim computes none of them.
Tissue also shifts the link itself at higher frequencies, and AirInduct Sim does not model ferrite, the titanium can of the implant or eddy currents in it. Treat its coupling numbers as the air-core baseline, not the final in-body figure.
From link sizing to exposure proof
A typical implant programme uses both, in this order:
- In AirInduct Sim, set the implant depth and footprint, then sweep turns and diameter until k and M meet the power budget.
- Sweep lateral offset and gap to cover how the external coil sits on different patients.
- Export SPICE for the circuit team and the PDF report with every dimension.
- Rebuild the chosen coils in Sim4Life, confirm the air-only field, then place them in a Virtual Population model and run the exposure analysis.
More on this in the medical devices use case, and in how the solver is validated.
Which should I use?
Use AirInduct Sim to size the coil pair for an implant power link, and Sim4Life to prove that link is safe in tissue; one does not replace the other. AirInduct Sim gives inductance, mutual inductance and coupling against depth and offset in seconds, which is what you need to choose diameters and turn counts and to hand the circuit team a SPICE model. It does not compute SAR, induced fields in tissue or heating, and it ignores the implant housing and any ferrite. Sim4Life does exactly that work, inside validated anatomical models, with the thermal and neuronal tools regulators expect. It is also far slower per design, so feeding it one sized candidate instead of twenty guesses saves weeks of compute and set-up. Medical-device teams should plan on both: AirInduct Sim early in concept, Sim4Life before any submission.
Compare with other tools
See all 20 AirInduct Sim alternatives and comparisons →Size the implant link before the body model.
Frequently asked questions
Does AirInduct Sim calculate SAR for implants?
No. AirInduct Sim computes coil fields in air, inductance and coupling; it has no tissue, SAR or thermal model. For exposure assessment of an implant link you need an anatomical solver such as Sim4Life.
Is there a free version of Sim4Life?
Sim4Life.lite is free for students with an educational email. It runs in the browser with EM-FDTD and EM-QS solvers, but is limited to 20 million grid cells, one Virtual Population model and no GPU or HPC solvers.
Which Sim4Life solver suits a low-frequency implant link?
For a few hundred kHz to a few MHz, the quasi-static EM-QS solvers are usually the efficient choice, since the body is small against the wavelength. EM-FDTD covers higher frequencies and full-wave effects.
Can I use AirInduct Sim results in a Sim4Life model?
Yes, as the starting geometry. Take the turns, radii and spacing from the AirInduct Sim PDF report, rebuild the coils in Sim4Life, and check the air-only field before placing them in the body model.