Polymer-Based Cables Offer MRI-Compatible Solution for Multimodal Imaging

MRI scans are known for their strict rules—magnetic and highly conductive materials are typically forbidden inside the machine due to risks of heating or interference. Yet for complex diagnostics and research, MRI often needs to be paired with other technologies that rely on conductive cables. Now, researchers at Empa, in partnership with Swiss company TI Solutions, have developed a novel polymer-based cable that operates safely and reliably inside MRI machines.

The innovation was part of an Innosuisse-supported project aimed at resolving a long-standing technical challenge in medical imaging. MRI, or magnetic resonance imaging, produces high-resolution views of internal tissues using strong magnetic fields and radio waves. Metal components, unless specifically engineered, pose risks by heating up or distorting the scans. This becomes especially problematic when MRI is combined with procedures like EEG, ECG, or temporal interference (TI) brain stimulation—all of which require conductive cables connected to external devices.

To address this issue, Empa’s Advanced Fibers laboratory in St. Gallen designed a new type of electrode cable composed primarily of polymer fibers. These fibers are coated with a microscopically thin layer of metal that strikes a balance between conductivity and MRI compatibility.

“Our goal was to develop a cable with very low but precisely defined metallic conductivity,” said Dirk Hegemann, the project’s lead researcher. “The conductivity must be high enough for signal transmission, but low enough to avoid interaction with radio waves.”

TI Solutions, which specializes in brain stimulation technologies, was a natural partner in the effort. “With the MRI-compatible cables developed in the Empa lab, our medical research partners can now—for the first time—visualize the effects of TI in the brain during MRI scans without interference,” added Sven Kühn, head of research and development at TI Solutions.

To meet performance and safety requirements, the team evaluated around a dozen different coatings and application techniques. The final solution was a composite of silver and titanium applied via magnetron sputtering. “Silver has excellent conductivity, while titanium slightly reduces it, allowing us to achieve the target range,” Hegemann explained. The combination also resists corrosion, adding to the cable’s long-term durability. One-year stress tests confirmed that the cables retained their conductivity with minimal change over time.

The coating, just under half a micrometer thick, is applied using an industrially scalable roll-to-roll process. Empa has already produced approximately one kilometer of coated fiber for prototype development. With the Innosuisse project successfully completed in 2025, the collaboration between Empa and TI Solutions is continuing through early-stage implementation and sampling support.

“If these cables prove effective in real-world use, they’ll move into full industrial production,” said Niels Kuster, president of TI Solutions AG. “Empa’s support in this pilot phase has been instrumental.”

The polymer-based cable solution could enable broader adoption of combined imaging and diagnostic techniques—safely bridging the gap between MRI and electrophysiological monitoring without compromising image quality or patient safety.